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					CT of the                                                                                                 Stomach:
Spectrum                                                                                                     of                            Disease1
Elliot                K           Fishman,                           MD
Bruce                    A. Urban,                           MD
Ralph                     H. Hruban,                                 MD


In evaluation                                   of gastric                   disease,                       computed                            tomography                                (CT)              has          proved
to be              a valuable                           adjunct                to barium                                studies                and             endoscopy.                              CT          clearly
demonstrates                                     the        primary                    pathologic                              condition                        and           shows                    extension                         of
disease                   to adjacent                             or distant                       structures.                            Useful                in staging                       gastric                 cancer,
CT          has           also          proved                    valuable                   in detecting                                  and          defining                       the          extent                of other
gastric                  neoplasms                           such            as lymphoma,                                         leiomyosarcoma,                                            and          metastasis                           to
the         stomach.                            Recent                advances                           in CT               technology                             such               as spiral                     CT-
coupled                       with              air contrast                       gastric                    studies                     and          a better                  understanding                                      of
the         need                to optimize                           CT          protocols-suggest                                                     that          the         value                of CT               in these
applications                               will           increase.                     CT           has            also           been               shown                  to be              valuable                       in de-
tection                   and           differentiation                                 of other                        gastric                conditions                         such                 as benign                        tu-
mors,                 Helicobacterpylori                                               and              other                infections,                        various                   forms                 of gastritis
(radiation,                          eosinophilic,                             and               emphysematous),                                               ulcer            disease,                     M#{233}n#{233}trier
disease,                     and           varices.                 Adequate                            gastric                   distention                       is essential                           for         success-
ful        gastric                 CT.

. INTRODUCTION
The stomach is involved                                               by a spectrum                                 of pathologic                          processes                     that          range            from            in-
flammatory                         and          infectious                  disease                to       benign                and          malignant                    tumors.                 The            clinical             mani-
festations                    of gastric                  disease            vary           from             severe                abdominal                     pain          in the               right          upper            re-
gion            and          acute              abdomen                to      vague                symptoms                        such             as weight                  boss          and           anemia.                In
most            cases,             computed                       tomography                          (CT)              is requested                      to better                demonstrate                           a patho-
logic           process                 seen            or suggested                        by other                     means                (eg,       an upper                      gastrointestinal                            radio-
graphic                  series            or     endoscopy)                      or       suspected                         on      the        basis           of the            clinical                manifestations.
In other                  cases,            gastric               disease           is first                noted             on        the        CT scan                 and          may            never            have            been
considered                        in the            differential                  diagnosis                       before             the        CT        examination                           (1).
        In this              article,             we        present               the        wide                 range            of gastric                  pathologic                     processes                       as seen
on         CT       scans.              These             gastric            processes                       include                 malignant                     tumors,                benign                   tumors,               in-
flammatory                         disease,               and        miscellaneous                                disease                processes.                    Emphasis                     is placed                  on        CT
signs           and          criteria             for       helping               distinguish                           between                 the        various               entities.                The           role        of CT
in      management                              of gastric               disease                  is also               addressed.




Index      terms:                 Gastritis,  72.291     . Peptic                 ulcer,           72.25     #{149}
                                                                                                               Stomach,               CT, 72.1211                  Stomach,
                                                                                                                                                                 #{149}                 diseases,           72.292          Stomach,
                                                                                                                                                                                                                          #{149}
infection,      2.2O                 Stomach.
                                   #{149}         neoplasms.                    72.30               Stomach,
                                                                                                 #{149}             varices,           72.75

RadioGraphics                      1996;         16: 1035-1054

I   From     the      Russell         H. Morgan             Department            of Radiology                    and     Radiological               Science       (E.K.F..        B.A.FJ.)         and      the      Department               of
Pathology             (R.H.H.).          Thejohns            Hopkins          Medical             Institutions,              Baltimore.          Md.      Presented            as a scientific              exhibit        at the        1995
RSNA        scientific            assembly.            Received        February            28.      1996;         revision         requested           April       2 and      received          April        30; accepted               May         6.
Address            reprint           requests            to E.K.F.,         Department                  of Radiology,              The     Johns         Hopkins           Hospital,          600      N Wolfe           St. Baltimore,
MI)     21287.


, RSNA,            1996




                                                                                                                                                                                                                                                         1035
                    .       TECHNIQUE                                OF GASTRIC      CT
                                                                                                                                                              Table 1
                    The           key to the                     detection  and staging                                       of gastric
                                                                                                                                                              Scanning                    Protocols                  for            astric              CT
                    disease              is a carefully                       performed                        CT      examina-
                    tion          of the         stomach                     and        the         classic            sites           of                                                                                          Model   of CT Scanner
                                                                                                                                                              Scanning                Parameter                                       Plus       Plus-S
                    spread              of disease,                       including                 local           lymph                  node
                    chains              and          the         liver.       The            examination                         must              in-        Acquisition                   time       (see)                                   24                           32
                    dude           gastric                 distention                  (with             positive                or        nega-              Kilovolt            peak            (kVp)                                       1 20                         120
                    tive        contrast                material)                    and       use         of iodinated,                           in-        Milliampere                    seconds               (mAs)                      2 10                         210
                    travenously                       administered                          contrast                 material.                                Section            thickness                 (mm)                           5 or         8                4 or          5

                    Protocols                  for         gastric            CT       are         optimized                   to          avoid              Table speed      (mm/see)                                                   5 or 8                       4 or 5
                                                                                                                                                              Pitch                                                                          1                        1.0-1.6
                    false-negative                          or     false-positive                         results.            In       the
                                                                                                                                                              Data reconstruction                                (mm)                     3 or 4                       3 or 4
                    past,         such          protocols                     were            developed                       specifi-
                    cally         for      dynamic                     CT;        however,                     all currently
                    recommended                          protocols                       are specifically                             for spi-
                    rab (helical)                     CT. Several                      commonly         used                          gastric            .       Pitfalls
                    CT protocols                           are listed                 below               (2-4).                                         The       maximum                          thickness                     of the             normal                 gastric
                                                                                                                                                         wall           at CT             is typically                   7-10           mm.               if the           stom-
                    .       Protocols                         for          Contrast                       Material                         Ad-           ach        is not              satisfactorily                     distended,                        the          gastric
                    ministration                                                                                                                         wall           may           appear                thickened,                       which              is sugges-
                                                                                                                                                         tive       of disease.                     This           potential                  pitfall             is most
                    Protocol                   1. -The                     orally           administered                           contrast              common                     in the            gastric              fundus                and           antrum.                      If
                    material            is 750 mL of a flavored           3% solution     of                                                             care         is not              taken,            this        pitfall           could               bead          to false-
                    diatrizoate               sodium    meglumine       (Hypaque;     Nyco-                                                              positive                or       false-negative                          CT         results.               Therefore,
                    med,           Princeton,        NJ) given    in split doses    over                                                                 if there               is any             doubt            about              the       adequacy                        of
                    30-45            minutes.                    The         last      dose             (250         mL)         is given                gastric              distention                    after         the       initial                scans           are         oh-
                    immediately                        before              the        patient              is placed                  in the             tamed,                additional                   oral         contrast                   material                 should
                    scanning                  gantry.              The        intravenous                          contrast                 mate-        be       given            and         several              delayed                   scans            should                  be
                    rial is 100-1                     10 mL of iohexol                                  (Omnipaque-3S0;                                  obtained.                    Some            articles              have              suggested                      obtain-
                    Nycomed)                     injected                  at a rate               of 2-3            mL/sec.                             ing       prone               or     lateral              decubitus                    views               as an             ad-
                    Scanning                  typically                   begins           approximately                              SO sec-            junct           to      the         standard                CT         study,               but        obtaining
                    onds          after         the         initiation                of contrast                    material                   in-      such            views              is usually               not          necessary                       and        is not
                    jection.                                                                                                                             part         of our                standard                imaging                   protocol.
                                                                                                                                                                 if tumor                   staging              with           gastric              CT        results                in
                    Protocol  2. -The                                      oral       contrast                 material                    is            understaging,                            possible                sources                of error                   include
                    1 ,000 mL of water                                     given           in split              doses           over                    inability                to detect                  adjacent                  organ               invasion,                      tu-
                        15-30           minutes.                  The         last         dose           (250         mL)            is                 mor          infiltration                    of       normal-sized                          lymph                 nodes,
                    given          immediately                            before             the         patient            is placed                    peritoneab                     carcinomatosis,                             and             liver           metastasis.
                    in      the         scanning                   gantry.             The              intravenous                        con-          If tumor                 staging              with             gastric              CT results                      in
                    trast         material                 is the           same            as in protocol                            1.                 overstaging,                        the          most           likely          sources                   of error                     in-
                                                                                                                                                         dude             enlarged                   nodes              without                 tumor                and          ap-
                    Protocol      3. -The     oral contrast                                                  material                   is 4-6           parent                invasion                of      adjacent                   organs.
                    g of effervescent     citrocarbonate                                                     granules                    taken
                    with 30 mL of water           immediately                                                  before                   scan-            .       CT       OF MAUGNANT                                             GASTRIC                            TU-
                    ning. The intravenous           contrast                                                material                  is the             MORS
                    same           as in protocols                                1 and            2.                                                    Worldwide,                          gastric             cancer                accounts                     for      nearly
                                                                                                                                                         half a million                           deaths            each           year.             In       the         United
                    . Scanning     Protocols                                                                                                             States,              gastric              cancer            is responsible                             for         more
                    The exact scanning     protocol                                                      depends                 on the                  than            13,000               deaths               and          24,000                new             cancer
                    model               of the             CT scanner                       and          the        available                   spi-     cases           per          year.          The           age-adjusted                           death            rate
                    ral     acquisition                      time           (24-40                 seconds).                  Typical                    varies           from              5.3       deaths              per          100,000                  males                 in
                    protocols                  for         our       current                equipment                      (Somatom                      the       United                 States         to 54.6 deaths                                 per          100,000
                    Plus          and         Plus-S             scanners;                   Siemens                 Medical                    Sys-     males            in       South              Korea   (5,6).
                    tems,           Iselin,            NJ)          are       shown                in Table                 1.                                   Gastric               cancer               occurs              twice               as frequently                               in
                                                                                                                                                         males            as in females.                            Reported                    risk          factors                 in-
                                                                                                                                                         dude             smoking                   and          dietary               factors               such            as ni-
                                                                                                                                                         trates,              nitrites,             and          pickled               vegetables.                         The
                                                                                                                                                         clinical               manifestations                            depend                 on         lesion               boca-




1036   U   Scientific             Exhibit                                                                                                                                                                                Volume                      16             Number                            5
Figure            1.          Diagrams              show           the     four       stages        of gastric              cancer            according                  to     a CT-based                staging           system             (10).          The         in-
set      diagrams              show            a cross        section             of the       gastric          wall        at the          tumor         site.      Small           lymph           nodes           are      seen       along               the
lesser         curvature                 of the      stomach;               normal-sized                   nodes        are     depicted                 as grayish               white.           The       liver         is outlined                 but         is de-
picted          as transparent.                     (a)      A stage            I tumor          (arrow)            is an intraluminal                            mass        that      invades            the       mucosa             (in)       without
tumor           spread.            (b)        A stage         II tumor             (arrow)          is associated                    with       a wall            thickness              of greater              than         1 cm        and           invades
through   the submucosa       into the muscularis        propria      (nip).                                                           (c) A stage III tumor     (arrow)                                      invades   the muscularis
propria  and serosa    (s). Enlarged      nodes (depicted        as reddish                                                              white)    are also seen in the                                      nodal chain.     (d) A stage
IV tumor    (straight arrow)     demonstrates     extension        through                                                              the serosa    into the peritoneal                                       cavity.  Enlarged    lymph
nodes          and        liver        metastasis             (curved             arrow)          are      seen.




tion        and         size           and       include             gastrointestinal                                                        niques           used,             which              included                 slow         delivery                    of
bleeding,                  abdominal                      pain,          and       weight               boss.                                contrast               material,                 slow          data           acquisition,                       and
There  are numerous         articles     on the accuracy                                                               of                    lack        of spiral               CT         data         sets.        Many             of the                corn-
CT in detecting     gastric      cancer.    An article   by                                                                                  monly            quoted                 articles            were           published                      in the
Minami    et al (7) is representative          of the usual                                                                                  late        1970s            and         early          1980s            (8,9).           Habvorsen
results.               They            found         that          in 71          patients               who                                 and        Thompson                       (10)          developed                     a CT-based
underwent                      surgery,              the          detectability                  of early                                    staging              system              for       gastric             cancer,             which                  is il-
and        advanced                      gastric           cancers              and        the      accuracy                                 lustrated               in Figure                  1 . A modification                              of this               sys-
of classification                             of gross             appearance                    and        sero-                            tem        is shown                     in Table              2.
sal      invasion                 as      determined                     with         CT       were             53%,                                There            has         recently                been         renewed                    interest                   in
92%,           80%,           and            80%,         respectively.                                                                      increasing                   the        accuracy                of CT            in the             detection
         The        published                   results            on the             accuracy               of CT                           and        staging               of gastric                 cancer.              Cho         et      al (11)
in staging                  gastric             cancer              have          generally               been                               used         a protocol                    of gastric                  distention                  with               wa-
somewhat                      disappointing.                          However,                   careful
analysis               of these                results            suggests              that       they
were           largely             related            to the             scanning                tech-




September                         1996                                                                                                                                               Fishman                     et al             U           RadloGraphics                     U   1037
                        Table 2
                        System  for               CT Staging                   of Gastric            Cancer

                        Stage                                      Description

                        I                    Intraluminal              mass
                        II                   Intraluminal                 mass        and gastric           wall
                                                thickness             >        1 cm
                        III                  Direct      tumor            involvement                of adjacent
                                                structures            (including               lymph           nodes)
                        N                    Distant         metastasis

                        Note-This                system     is a modification                          of the stag-
                        ing system             of Halvorsen      and Thompson                             (10).




                    ter (600-800       mL), rapid                               intravenous       injection
                    of contrast    material      (150                            mL of nonionic           con-                       Figure        2.       Stage         II gastric              adenocarcinoma                      in a 57-
                    trast material     injected     at                          a rate of S mL/sec          for                      year-old        woman            with           epigastric          distress.            CT      scan

                    30 seconds),      and two-phase                                    image    acquisition                          shows        a polypoid               gastric         mass        (arrow)             without               cvi-

                    (30 seconds      for the early                                phase     and 2 minutes                            dence       ofextension                 beyond               the stomach.               No      evidence
                                                                                                                                     of metastasis             is seen.
                    for the equilibrium         phase).                              In a study     of 52 pa-
                    tients           with      pathologically                     proved             gastric            can-
                    cer,        41     had      moderate                  to     marked          heteroge-
                    neous  lesion   enhancement                                     in the early                     phase           using        dual-phase                 spiral          CT        with          narrow                 colli-
                    and homogeneous         lesion                                enhancement                        in the          mation          and       close           interscan                spacing               (ie,         4-mm-
                    equilibrium                 phase.             These          enhancement                        pat-            thick       sections             reconstructed                       at 3-mm                 intervals)
                    terns   correlate     with the classic angiographic                                                              to determine                  if this           protocol            could             further                in-
                    appearance         of gastric   cancer:    neovascularity                                                   in   crease        the        accuracy                 of CT.          Such          a protocol
                    the arterial      and capillary     phases    and tumor                                                          would         surely          increase                the       accuracy               of liver               me-
                    staining   in the venous     phase.      The primary      tu-                                                    tastasis        detection,                which               is often            a key          compo-
                    mor was detected       in five of nine cases of early                                                            nent        in the        staging               of    gastric            cancer.
                    gastric  cancer   and 4 1 of 43 cases         of advanced
                    gastric  cancer.   The overall      detection    rate was                                                        .        Adenocarcinoma
                    88%. When       correlated       with results     of TNM                                                         Adenocarcinoma                          is the           most        common                     primary
                    staging,   CT was 65% accurate            in determining                                                         gastric         tumor;           approximately                           95%          of primary
                    depth    of tumor      invasion,     83% accurate      in de-                                                    gastric         neoplasms                  are        adenocarcinomas.                                     It is
                    termining                degree           of     serosal            invasion,              and       70%         often    fatal,          with a 5-year    survival                               rate      of ap-
                    accurate       in demonstrating       regional     lymph                                                         proximately                20%. Adenocarcinoma                                          can be clas-
                    node     metastasis.                                                                                             sified      into       four          types:          papillary,             tubular,                  muci-
                        These       authors’   results are interesting       be-                                                     nous,        and       signet-ring                   cell.
                    cause     their study     was performed        with dynamic                                                           The CT appearance               is variable.      Common
                    CT (single                scans          acquired                 nearby        every         S sec-             appearances        include       the following          (1 2- 1 4): a
                    onds),            generally          with             10-mm-thick                  sections.               It    focal lesion      with wall thickening               (Fig 2), dif-
                    would             be interesting                 to duplicate                   their        study         by    fuse infiltration       (linitis    plastica)     (Figs 3,         a                                 4),


                                                                                                                                     bulky        mass         with          ulceration                 (Fig         5),     and           a
                                                                                                                                     bulky        tumor            that       simulates                lymphoma                      or         sar-
                                                                                                                                     coma         (Fig      6).




1038   U   Scientific            Exhibit                                                                                                                                                   Volume                16           Number                     5
3a.                                                                               3b.




4a.                                                                            4b.
Figures     3, 4.    (3) Stage III gastric     adenocarcinoma         in a 47-year-old         woman      with a history     of persistent                        post-
prandial    emesis    and abdominal      discomfort.       Spiral CT scans show infiltration              of the stomach       by tumor.                        Several  cc-
liac nodes    are present    (arrow).   (4) Stage      IV gastric  adenocarcinoma              in a 76-year-old     man with a history                           of gen-
eral malaise     and loss of appetite.      (a) CT scan shows         infiltration       of the stomach        with a linitis plastica-type                             ap-
pearance.    (b) CT scan at the level of the umbilicus             shows        carcinomatosis       with implants       on the greater                         omentum
(arrows).




a.                                                                                 b.
Figure   5.     Stage IV gastric  adenocarcinoma               in a 62-year-old            woman       with         weight       boss     and   abdominal       pain.     Spi-
ral CT scans     show  a large, ulcerating        gastric     tumor     with      spread      beyond          the     gastric     wall.     There     is evidence        of ad-
enopathy     in the cebiac nodal chain        (arrow).




September            1996                                                                                              Fishman             et al       U     RadioGraphics        U   1039
                    Figure         6.        Stage          IV gastric            adenocarcinoma                         in a 67-
                    year-old           man        with          a history         of abdominal                  pain       and           Figure          7.        Recurrent               stage          N gastric               adenocarci-
                    gastrointestinal                     bleeding.             Spiral     CT      scan      shows              a         norna         in a 59-year-old                   man         with          nausea           and      vomiting
                    barge, ulcerating,                    exophytic   gastric   mass                         with liver                  who had undergone                            partial gastrectomy                               for gastric
                    metastases.      The                 mass appears    to involve                         the pan-                     adenocarcinoma.                         Spiral CT scan shows                                 recurrent     gas-
                    creas.                                                                                                               tric     adenocarcinoma                         (arrow)             with          adenopathy                and
                                                                                                                                         liver      metastases.



                           Nodal         spread                 of    disease           may       extend                into       or    and       solid          ovarian           mass              that          is usually              indistin-
                    around             the    region                 of the           gastrohepatic                     biga-            guishabbe                from           a primary                   ovarian              tumor.             Kim
                    ment (Fig 7). Nodes                                 in this          region           are          consid-           Ct      al (18)          reported               a case              of gastric                 metastasis
                    ered positive     if they                           are 8 mm                or greater                 in di-        to the          uterus           and       reviewed                   the           literature;              they
                    ameter   ( 1 5). Tumor                              spread           to these               nodes              may   found           that       such          metastasis                   is more                  common                in
                    also       occur         in breast                  cancer,            esophageal                    can-            younger                 women.             The            most          common                     sites        of
                    cer,       and       lymphoma.                      CT is especially                        useful             in    origin          for      uterine           metastasis                       are       gastric          and
                    detecting         unsuspected        or distal sites of tumor                                                        breast cancer.
                    spread       including        the liver, pelvis,    and ovaries                                                          CT may be helpful                                   in determining                            spread             to
                    (Figs     8, 9).                                                                                                     adjacent                organs           like       the         pancreas                    and       spleen.
                          Pelvic     metastases       may take the form of drop                                                          However,                  detection                of extension                          may         be diffi-
                    metastases                on          the        sigmoid            colon        or     rectum,                      cult.         Sussman              et     al (13)             evaluated                   75      patients
                    metastasis               to      the         ovaries            (Krukenberg                      tumor),             with          gastric        cancer               and         found               that         47%         were
                    or (rarely)              metastasis                     to the        uterus          (16-18).                       incorrectly                staged           with             CT;       3 1 % were                  under-
                    Krukenberg                     tumor              may        be     unilateral              or      bilat-           staged,           and       16% were                    overstaged.                      The         most
                    eral and has a diameter   of 1 -20 cm (Fig 8).                                                                       problematic                  aspects               of staging                     were          accurately
                    The classic CT appearance    is a mixed cystic                                                                       detecting      adenopathy         and                               determining                   pancre-
                                                                                                                                         atic invasion.      It is difficult                                 to detect                invasion     be-
                                                                                                                                         cause          of the        intimate                relationships                          of these
                                                                                                                                         structures.                However,                    the       poor             results         of this




1040   U   Scientific           Exhibit                                                                                                                                                            Volume                    16            Number                  5
8.                                                                                                                              9.
Figures              8, 9.    (8) Stage N gastric     adenocarcinoma            with    metastasis        to the ovaries  after one                                                                                         course        of chemo-
therapy             in a 61-year-old   woman      with known         metastatic      gastric      cancer.    Spiral CT scan shows                                                                                            large,      complex,                   cys-
tic    and      solid      pelvic            masses           compatible                  with      Krukenberg                        tumors             involving             the      ovaries.            This       diagnosis               was         proved
at percutaneous                       biopsy.           (9)      Stage       IV gastric             adenocarcinoma                              with         metastasis                 to the          ribs      in a 55-year-old                     man
with         a history           of gastric             cancer        and          increasing             right           rib        pain.      Spiral         CT       scan          shows            a large,        destructive                   lesion
that      involves             the     ribs,      consistent               with          metastasis.



study          may        be         largely          due        to the           fact      that        the                                        An unusual                         appearance                      of primary                     adeno-
data         were        collected                   from         1980        to         1986.      Today,                                   carcinoma                    of the              stomach                is mucinous                       carci-
spiral         technology                      and      better           image             resolution                                        noma,             which                 may         partly            calcify            (20,21).                The
may          help        one         avoid           these        problems.                                                                  calcifications                      have            been            described                as      nodular,
     One variant     of adenocarcinoma            consists   of                                                                              miliary,            or       punctate                    and        may          be      hornoge-
large tumor      masses     5-14    cm in diameter                                                                                           neously                 distributed.                  A gastric                  mass         that         partly
(mean,      9 cm) and tumor        growth       with a large                                                                                 calcifies               is more               typically               a leiomyoma                        or      (less
extraluminab      component        (19). This type of tu-                                                                                    frequently)                   a leiomyosarcoma.
mor, known        as exophytic        adenocarcinoma,                                                                                              CT is also                   valuable                 for       follow-up               after            gastric
may          arise       in any              portion             of the           stomach                but      is                         surgery             such           as partial                  or      total          gastrectomy
most          commonly                     seen          in the            body           and       antrum.                                  (22,23)             (Fig          7).      Common                     sites           of recurrence
The          appearance                   is usually                similar              to that         of                                  include             the        liver,            local         nodal            groups            such            as
gastric             beiomyosarcoma.                              According                  to     Lee        et al                          the gastrohepatic   nodes,   and the                                                        gastrectomy
(19),    thickening     of the gastric       wall adjacent     to                                                                            bed. All can be well defined     with                                                       CT. Compli-
the exogastric       mass is typical       of exophytic      ad-                                                                             cations            of partial                  or     total          gastric             resection                such
enocarcinoma         and allows    distinction      from gas-                                                                                as ulceration,                          perforation,                    and           obstruction                   can
tric beiomyosarcoma.          However,        our experience                                                                                 be detected                       with          CT.
with this sign has been          variable.       In most
cases,          differentiation                        is of little           importance                       be-
cause    endoscopy                             with          biopsy         will          invariably                 be
performed.




September                       1996                                                                                                                                                  Fishman                     et al              U     RadioGraphics                   U   1041
                    Figures       10, 11.          (10)      Biopsy-proved             gastric     lym-
                    phoma      in a 74-year-old        woman       with abdominal            pain
                    and gastrointestinal          bleeding.      Spiral CT scan shows
                    marked      thickening       of the gastric       folds that extends            up
                    to the esophagogastric             junction.     Ulceration        in the gas-
                    tric fundus      is also seen. (11) Biopsy-proved                  large cell
                    gastric   lymphoma         in a 62-year-old         woman       with ab-
                    dominal      pain and fullness          in the left upper         quadrant.
                    CT scans show gastric             fold thickening,         extensive        ad-
                    enopathy       in the porta       hepatis     and paraaortic          zones,
                    and splenomegaby.



                    . Lymphoma
                    The stomach       is the most frequent         site of lym-
                    phomatous      involvement       of the gastrointestinal
                    tract;  such  involvement       makes     up approxi-
                    mately    3% of gastric    tumors     (24,25).     Non-
                    Hodgkin          lymphoma               accounts             for approxi-
                    mateby        80%     of cases           of gastric           lymphoma.
                    Lymphoma              has      a variety          of appearances                such
                    as a polypoid               form,       an     ulcerating          form,       and     a
                    combination             of these             forms.         if evaluation        is
                    based     strictly    on CT criteria,                       lymphoma           may
                    sometimes          be indistinguishable                         from       adenocar-
                    cinoma.
                        Gastric bymphoma    is characterized        by thick-
                    ening of the stomach     wall (Fig 10). In a re-
                    view of 23 patients  with    gastric     lymphoma,
                    Megibow     (26) found     an average   wall thickness
                    of 5 cm (range,    2.5-8      cm). Buy and Moss (27)
                    found   an average   wall thickness     of 4 cm in
                    their series of 1 2 patients.     The CT patterns      of                                                                            ..     ‘.    1      .
                                                                                                                                                                                   .   --.,

                    gastric  involvement      are (a) diffuse  infiltration
                    that involves     more   than 50% of the length             of                              Figure  12.   Gastric lymphoma                                          in a 72-year-41d                       man
                    the stomach      (Fig 1 1), (b) segmental      infiltration                                 who underwent      CT for staging                                      of lyniphoma.                     CT

                    of the stomach,       and (c) a localized   pobypoid                                        scan       shows          marked         thickening                    of the            gastric       folds
                                                                                                                with       extensive          adenopathy                   and         ascites.            Extensive            dis-
                    form often    associated     with an ulcer    and occa-
                                                                                                                ease was           also     present           in the         mesentery                     and       small
                    sionally       with     perforation.
                                                                                                                bowel.
                       Tumor       infiltration               is usually     homogeneous
                    on cross-sectional                    images,     although      regions                of
                                                                                                                low        attenuation                may            be     seen              (Fig         1 2).     Most
                                                                                                                patients           with        gastric               bymphoma                        have           associ-
                                                                                                                ated       adenopathy.                   One              of the              key        points         in dii-




1042   U   Scientific          Exhibit                                                                                                                                Volume                        16             Number              5
14a.                                                                                                        14b.
Figures           13,      14.         (13)          Gastric         beiomyosarcoma                      in a 70-year-old             man with            abdominal                 pain        and left upper                      quad-
rant      fullness.  CT scans                        show      a mass larger than 20 cm in diameter         that invades    the spleen    and left kidney.     The                                                                             tu-
mor       extends   downward                            to invade    the left psoas muscle     as well. (14) Gastric     beiomyosarcoma       in a 64-year-old
man       with gastrointestinal                           bleeding    who underwent      endoscopic     biopsy    of the tumor.     CT scans show the tumor
arising         from       the      posterior             gastric        wall.      The      patient            also   developed           metastasis              to     the     left     iliac        crest.




ferential              diagnosis                of     gastric         lymphoma                   and                        gastric           leiomyosarcoma                            appears                 as barge           (aver-
adenocarcinoma                            is that             in bymphoma                   the                              age diameter,                     1 5 cm),            spherical                  or ellipsoid
nodes           are      usually           bulkier               and     extend           beneath                            masses            that      are       best         described                 as exogastric
the       renal         hilum.          Another                  key     differential               diag-                    (Fig       1 3). The           tumors               are often                necrotic,                 a fea-
nostic          point            is the         difference               in wall          thickness                          ture       that      is highlighted                     if iodinated,                       intravenous
between   adenocarcinoma                                          (usually  1 -3 cm)                                         contrast            material               is used.           They           may            ulcerate
and lymphoma        (average,                                    5 cm). Patterns     of                                      and       occasionally                  may          perforate.
contrast               enhancement                        have         not       been       reliable                                Gastric            leiomyosarcoma                              may           invade             adja-
in our          experience.                     Gastric             involvement                   with                       cent        organs           like       the         spleen            or        pancreas.                 Meta-
bulky        tumor               masses              is not         uncommon                  in                             static       spread            to     the      liver         may           be       seen;        cystic           or
American                 Burkitt           lymphoma.                     Gastric          bym-                               necrotic             metastasis                is common.                           Tumor              spread
phoma             has       a better                 prognosis               than       gastric           ad-                may        also         involve            a portion                of the            peritoneal
enocarcinoma.                                                                                                                cavity.           The       pattern            of spread                   of leiomyosar-
                                                                                                                             coma          is similar              regardless                   of the            site      of origin
.      Leiomyosarcoma                                                                                                        (ie,      stomach,                uterus,           small           bowel,              or muscle)
Gastric           leiomyosarcoma                              is an unusual               tumor            of                (Fig       14).
smooth            muscle             origin            that       represents              1%-3.5%
of gastric              malignancies                     (28-30).             Approximately
two-thirds                of smooth                   muscle           tumors           of the           gas-
trointestinal                tract        arise          in the         stomach.            At CT,




September                    1996                                                                                                                                Fishman                   et      al         U          RadioGraphics               U   1043
                        15a.                                                                                                                                  15b.
                    Figures                  15,       16.             (15)        Gastric            beiomyosarcoma                              in a
                    79-year-old                      woman                 with         a &month              history                of back
                    and          beg        pain.           Spiral         CT      scans           show           an      exogastric
                    mass             with         heterogeneous                           enhancement.                         The         mass         cx-
                    tends             posteriorly                    and        downward                  to invade                  the      spbenic
                    vessels             and          tail      of the           pancreas.              (16)            Gastric             leiomyo-
                    sarcoma                   in a 69-year-old                          man        with       a history                 of gas-
                    trointestinal                      bleeding.                  CT       scan       shows              a large            exogas-
                    tric mass                  that arises                  near the gastric                       fundus.                 Minimal
                    ulceration                   is present                  in the tumor.



                               Distinction                      between                    beiomyoma                          and       beio-
                    myosarcoma                                is usually                 possible             on          the        basis             of
                    lesion              diameter                      (usually                    1 0 cm           for        beiomyosar-
                    coma),                   location,                    and      tumor              necrosis                  (Figs         15,
                    16). However,      in select cases leiomyoma                                                                            may
                    appear  aggressive     and be indistinguishable                                                                           from
                    sarcoma                       solely             on     the         basis         of CT             criteria.             Leio-
                    myosarcoma                                may           calcify,            but       in our              experience
                    this         is rare.


                    .          Liposarcoma
                    Other               types                of sarcoma                       may         also           involve              the
                    stomach.                        The          second                 most          common                        type          is li-
                    posarcoma                             (3 1).          This          tumor             is rare              and          may
                    look              nearly              identical                 to a leiomyosarcoma                                           if fat
                    is         not      definable                      on         the      CT scan.                    Liposarcoma
                    is usually                      very             aggressive.


                    .          Metastasis
                    Metastasis                        to       the         stomach                 (Fig           1 7)        occurs              in
                        less         than           2%        of patients                     who           die          of      cancer.
                        Spread               to      the         stomach                   may         be         hematogenous
                                                                                                                                                                 Figure          21.          Adenocarcinoma                              ofthe           colon      metastatic
                        (eg,         malignant    melanoma       or breast  cancer)
                                                                                                                                                                 to the         stomach               in a 51-year-old                       man         with      a history             of
                        (Fig         18), by direct    extension    (eg, pancreatic
                                                                                                                                                                 metastatic                colon         cancer.            CT       scan         shows          tumor         im-
                        cancer               or hepatoma)                           (Figs             19,     20), or by bym-
                                                                                                                                                                 plants         on     the         gastric         antrum              (arrow).
                        phatic              spread    (eg,                      esophageal                    or colon  can-
                        cer)         (Fig           21)        (32-34).                  Metastatic                     disease              varies
                        in appearance                                from          bulb’s-eye-type                              lesions                in        cancer.              In     select            cases,            the         appearances                   of        a
                        melanoma                      to a linitis                      plastica            pattern                  in breast                   primary               gastric               cancer            and          metastatic                disease
                                                                                                                                                                 can       he        identical.                To       make             the       correct            diagno-
                                                                                                                                                                 sis,     careful             attention                 must            be        paid          to the     clini-
                                                                                                                                                                 cab history.




1044   U   Scientific                 Exhibit                                                                                                                                                                               Volume                   16            Number                     5
17.                                                                                            18.
                                                                                                       Figures          17-19.           (17)       Biopsy-proved                      metastatic         ova-
                                                                                                       rian cancer     in a 63-year-old                       woman           with a history                of
                                                                                                       ovarian   cancer.    Follow-up                        CT scan         obtained    after             die-
                                                                                                       motherapy            shows        implants             on     the     gastric          antrum.       The
                                                                                                       resultant     narrowing       of the antrum        caused     delayed         gas-
                                                                                                       tric emptying.        (18) Melanoma         metastatic       to the stom-
                                                                                                       ach in a 5 1-year-old        man with a history           of malignant
                                                                                                       melanoma.         CT scan shows       a 1 .5-cm-diameter           ulcerat-
                                                                                                       ing metastasis        to the gastric     wall (arrow).        (19) Pan-
                                                                                                       creatic    cancer     with direct    extension        into the stomach
                                                                                                       in a 60-year-old        man with a history          of pancreatic          ad-
                                                                                                       enocarcinoma.           CT scan shows       direct     tumor     extension
                                                                                                       into the gastric        body and antrum          with tumor         infiltra-
                                                                                                       tion (arrow).




19.




Figure        20.        Adenocarcinoma                 of the transverse           colon    invading            the stomach            in a 73-year-old                   woman           with     guaiac-
positive       stools       and       bad   breath.      Spiral    CT    scans     show     a large,      ulcerating             mass    in the       left     upper          quadrant.             The
mass       is most       suggestive          of an    ulcerating        gastric    leiomyosarcoma.                 At   resection,         the      mass       was         found          to be     a tumor
of the      distal      transverse          colon     that    invaded       the   stomach      by means            of a gastrocolic              fistula.




September                 1996                                                                                                          Fishinan               et al               U        RadloGraphics         U   1045
                    23L                                                                                                    23b.
                    Figures         22, 23.      (22)        Gastric          beiomyoma         in a 72-year-old                man with           a history         of vomiting           bright           red blood            fob-
                    bowed         by dizziness     and       fatigue.         (a)   Spiral     CT scan       shows             a smooth,          ulcerating          mass       in the        gastric          fundus.         (b)      Re-
                    constructed          view    shows        that      the     mass      is submucosal             (arrow),         consistent          with        beiomyoma.             At resection,                 the     mass
                    was found     to be a leiomyoma.     (23) Gastric     leiomyoma     in a 57-year-old  man with                                                       a 2-year history    of abnormal     re-
                    suits on liver function     tests. CT scans show       a mass that arises from the posterior                                                         gastric  wall (arrows)     and con-
                    tains areas of necrosis;     it was suspicious    for a malignancy.     At resection,  the mass                                                      was found     to be a leiomyoma.



                    S CT OF BENIGN                       GASTRIC                       TUMORS                                     may      ulcerate             or   perforate             (Fig          22).      Exogastric
                                                                                                                                  leiomyoma               may        be difficult                to distinguish                   from
                    . Lelomyoma                                                                                                   a malignant              process              (Fig      23).       Both          beiomyoma
                    Gastric   leiomyoma       is the benign                              counterpart           of                 and      beiomyosarcoma                      occasionally                      enhance               af-
                    malignant     leiomyosarcoma        and                            is the most                                ter injection                of iodinated           contrast                   agents          (up         to
                    common             benign      gastric           tumor          (35,36).        It ac-                        1 .5 times           baseline)             or calcify.
                    counts         for approximately                    2.5%        of all gastric           tu-
                   mors.   The lesions               are usually     submucosal       but                                         . Lipoma
                   may be exogastric                  in select   cases.   Leiomyoma                                              Lipoma   is a rare                  gastric          tumor         that          is usually
                   varies  in diameter               (usually    <5 cm) and is usu-                                               detected    as an incidental         fmding.   The                                       lesions
                   ally asymptomatic,                  although    in some      cases   it                                        are of variable      fat attenuation       and are                                      often
                                                                                                                                  smooth    walled.       Lipoma     of the stomach                                           has no
                                                                                                                                  malignant     potential      but if large enough                                            can
                                                                                                                                  bead to an intussusception.




1046   U   Scientific         Exhibit                                                                                                                                              Volume                  16        Number                    5
                                                                                     Figures   24, 25.       (24) Hpylori      infection     in a 52-year-
                                                                                     old woman       with a history   of gastric       ulcer disease     and
                                                                                     a 3-day history     of nausea,  vomiting,        and inability    to
                                                                                     keep       food       down.          Spiral          CT scans           show           gastric          wall
                                                                                     thickening       especially         in the gastric       fundus.       The differ-
                                                                                     entiab diagnosis         included         bymphoma         and adenocarci-
                                                                                     noma.      Endoscopy          and biopsy         showed       gastric     ulcers
                                                                                     and Hpj’lori        infection         but no evidence            of malignancy.
                                                                                     (25)    Hpylori       infection         in a 49-year-old         woman       with a
                                                                                     long history       of gastric        hypersecretion.           Gastric      secre-
                                                                                     tion tests revealed            elevated      gastrin     levels.     (a) Spiral
                                                                                     CT scan           shows          a focal        mass       approximately                      1 .8 cm in
                                                                                     diameter           in the         gastric       antrum           (arrow).              (b)     Coronal
                                                                                     reconstruction                   shows         the      mass      clearly         (arrow).              The
                                                                                     mass       was       resected,           and     pathologic                 analysis          showed
                                                                                     enlarged          lymphoid               nodules          infiltrated             by Hpj’lori.

25L
I                                                                                     lori      resides           within            the      mucosal                layer         of    the
                                                                                      stomach,  especially                            in the antral  region.  Up to
                                                                                      60% of adults    over                         60 years   of age are infected
                                                                                      but       are     usually           asymptomatic.                          H pylon                is
                                                                                      found   in up                   to 80% of patients    with an active
                                                                                      gastric  ulcer                   and in nearly   100% of patients
                                                                                      with chronic                      gastritis. The role of Hpylori     in
                                                                                      gastric          cancer            is more             controversial.                       However,
                                                                                      studies           show           that         80%-90%                 of     patients             with
25b.
                                                                                      gastric          cancer            that       arises          outside            the        cardia            of
                                                                                      the stomach   have antibodies     to H pylon.
                                                                                      There is also an increased    incidence    of B-cell
. CT OF INFlAMMATORY                                     GASTRIC              DIS-    lymphoma                  in patients                  with          Hpylori                infection.
EASE                                                                                  At CT,           Hpyloni                infection              can         simulate              an     infIl-
                                                                                      trating          carcinoma                 or focal             gastric           mass           (Figs
. Helicobacterpylori                            Infection                             24,       25).
One of the most interesting                        and      complex           top-
ics     in the     discussion         of gastric         disease      is the
Helicobacter            pylon        bacillus      (37-43).          Previ-
ously      known         as     Campylobacter               pylon,       H py-




September              1996                                                                                              Fishman                    et al          U          RadioGrapbics              U   1047
                                                                          -   ‘::.     ‘“‘

                                                                         <(%         ‘-i,:




                    Figures           26, 27.   (26) Gastritis in a 65-year-old
                    woman            with severe right and left upper quadrant
                    pain. CT scans show        marked                                  thickening     and nodu-
                    barity, which   are suspicious                                   for neoplasm       (arrow).   En-
                    doscopy     and biopsy   showed                                   changes     compatible     with
                    acute         and chronic                gastritis.              (27)       Gastritis           in a 62-year-
                                                                                                                                                                                                ;,
                                                                                                                                                                                           tv

                    old woman          with severe       upper      abdominal                                       pain and
                    gastrointestinal        bleeding.      CT scan shows         markedly                                                                                                  ‘‘:
                                                                                                                                                                                                                                        ‘p
                    thickened        and edematous          gastric     folds in a pattern
                    suggestive       of severe     inflammation          with edema.       Cay-
                    ernous   transformation                        of the portal vein is also seen
                    (arrow).    Endoscopy                       showed    gastritis without  cvi-
                    dence ofHpylori                         infection.




                    .       ConventlonalGastritis
                    Gastritis           has      a number                        of common                       and         tin-
                    COmrnOfl                causes           such             as alcohol                  abuse,             aspi-
                    nfl,      and       other          medications.                           In     most           cases,           gas-
                    tritis appears     as thickened    gastric                                                 folds     or wall
                    thickening     with wall attenuation                                                   similar         to that          .       Gastric             Ulcer           Disease
                    of soft tissue                   (44)        (Fig          26).          Rarely,            it has         low          CT is often                  the     initial             study       performed                   in a pa-
                    attenuation                 due  to edema   (Fig                                 27). Low                 attenu-       tient       with           an acute            abdomen.                   In this          clinical
                    ation         due       to edema     or to mucin                                   infiltration                of       scenario,             OflC         of the           potential             causes           is gastric
                    the underlying                     muscle   and soft tissue has also                                                    ulcer       disease            with           or without                  l)crforatiofl.                  Al-
                    been reported                     in mucinous    adenocarcinoma      of                                                 though             a perforating                         ulcer    may         manifest               as
                    the stomach.                     Gastritis can he confused      with                                                    pneumopentoneum,                      in other   Cases   the perf#{246}-
                    tumor           infiltration                on        CT scans,                      and      the        diagno-        ration        is focal      and the free air may be localized
                    sis     can      then        he         made              only           with        biopsy.             A false-       or walled              off (Fig 28). In these      ascs,    CT may
                    positive            diagnosis                of gasti-itis                     can     result            from           demonstrate                walled-off    air or air bubbles    as ab-
                    poor          gastric        distention.                                                                                scesses            (45).       Jacobs               et     al (46)        described                 the
                                                                                                                                            findings            in 35          patients                with      peptic           ulcer         dis-
                                                                                                                                            ease.       The        findings               included               CT       evidence               of
                                                                                                                                            perforating      or penetrating          ulcer,                                 gastritis            with
                                                                                                                                            wall thickening,        pneurnoperitoncurn,                                                   and         free




1048   U   Scientific             Exhibit                                                                                                                                                             Volume              16           Number                5
Figure      28.        Gastric       ulcer       disease       in a 7l-year-ld            woman    with      acute        abdomen.              CT scans             show           hydropneumo-
peritoneum          with the free air best seen anterior                            to the liver    (arrow   in a). The gastric    fundus    is dilated,                                        and      there
is perforation         of the gastric anti-tim. Note the                         free air near     the perforation     site (arrow    in b).



                                                                                                    (5,000           rad)       over        a 5-week                period     (47).                   The
                                                                                                    changes              are     noted            1 month                to 2 years                after
                                                                                                    therapy.             At our           institution,                  radiation            gastritis
                                                                                                    occurs     most often         in patients     who undergo           ra-
                                                                                                    diation    therapy       after a Whipple        operation       for
                                                                                                    pancreatic       cancer.       The thickening        is usually
                                                                                                    seen in the area of gastrojejunostomy                     that cor-
                                                                                                    responds                to the         peak          radiation             dose          center.
                                                                                                           The        CT and             pathologic                features                of radiation
                                                                                                    gastritis            are    fairly        consistent.                  Gastric              wall       thick-
                                                                                                    ening          in a symmetric                        pattern            is often             seen.
                                                                                                    Small         ulcerations                may         be    visible,              and        the      mu-
                                                                                                    cosa        may         appear          “shaggy”               at     CT. Gastric                  inflam-
                                                                                                    mation            and       ulceration               can result                 in perforation.
                                                                                                    One         key to recognizing                         radiation                 gastritis    is not
Figure      29.      Radiation    gastritis     in a 70-year-old
                                                                                                    to confuse                 it with          recurrent                or residual               tumor.
woman       after a Whipple         operation       for pancreatic
                                                                                                    Although      the appearance          may be nearby identi-
cancer     and postoperative          radiation      therapy.      CT scan
                                                                                                    cal in select    cases,     radiation    gastritis   typically
shows     thickening        and narrowing         of the gastric      an-
ti-tim (arrows),       which    correspond         to the radiation                                 demonstrates        sharp     margins    that correspond        to
ports.                                                                                              the therapy      ports    (Fig 29). Pathologic          injury to
                                                                                                    the epithelium         of the stomach        results   in mu-
                                                                                                    cosab        ulceration               and       sboughing.                Frank             ulceration
extravasation          of contrast   material.                        Other      flOfl-             may         occur;         the       probability               depends                 on      the       cx-
specific      findings    bike mesenteric                          or peritoneal                    tent        of associated                vascular              injury.
inflammation              were            also    seen.


.    Radiation                Gastritis
Radiation         gastritis          occurs          most      commonly             in
patients         who      receive            doses         above      50 Gy




September              1996                                                                                                            Fishman                et al             U          RadioGrapbics            U   1049
                    Figure       30.          Eosinophilic          gastroenteritis   in a 46-year-old                  woman           with      abdominal               pain     and diarrhea.                  CT scans
                    show       thickening           of the      gastric    antrum and dilated     loops                of proximal              small       bowel.         The     small         bowel           folds       have       a
                    wet appearance.                These        findings     are most suggestive     of              eosinophilic             gastroenteritis.               Minimal             fluid         in the     mesen-
                    tery     is also     seen.




                    a.                                                                                                    b.
                    Figure        31.         Biopsy-proved                           disease
                                                                          M#{233}n#{233}trier            in a 48-year-old           man with             marked        gastric         fold thickening                   through-
                    out the      stomach.           CT scans            clearly     show      large,     lobulated     folds        in the     gastric       fundus.



                    .    Eosinophilic              Gastritis                                                                   . CT OF MISCELLANEOUS                                                     GASTRIC
                    Eosinophilic          gastroenteritis        is an uncommon                                                DISEASE
                    disease      of unknown             origin.   The pathologic
                    findings      consist       of eosinophilic       infiltration        of                                   I                     Disease
                                                                                                                                      M#{233}n#{233}trier
                    the stomach           or bowel         in the mucosa,          submu-                                      M#{233}n#{233}trier
                                                                                                                                             disease                   is an uncommon         disease     of
                    cosa, or muscularis.                The clinical     manifestations                                        unknown      origin                   that results   in hypertrophy          of
                    range       from          chronic          symptoms               such      as malab-                      the gastric    folds.                  The enlargement       most      corn-
                    sorption            and      diarrhea         to acute            symptoms             such                monly         occurs              in the      gastric            fundus,            but       any
                    as gastrointestinal                     bleeding,             abdominal            pain,                   part      of the stomach       may be involved.                                           At CT,
                    and obstruction     (48,49).     CT of the stomach                                                         this     entity   may simulate      an infiltrating                                        process
                    shows   a thickened      gastric    wall (usually  1 -1.5                                                  like     lymphoma      (50,51)    (Fig 31). Rare                                          reports
                    cm) (Fig 30); antral      involvement      is most corn-                                                   in the        literature            have       described                  gastroduodenab
                    mon.  Concurrent      stomach       and small bowel       in-                                              intussusception                     secondary               to      this         condition.
                    volvement               is also     common.                                                                Case      reports            have          noted         adenocarcinoma                             of
                                                                                                                               the stomach         in patients                         with         bong-standing
                                                                                                                                             disease.
                                                                                                                               M#{233}n#{233}trier




1050   U   Scientific          Exhibit                                                                                                                                            Volume                  16        Number                  5
32a.                                                                                                                            32b.




33a.
Figures                32,         33.        (32)       Emphysematous                         gastritis          in a 63-year-old         woman             with       a history          of hemolytic              anemia,            dia-
betes,           and         increasing              abdominal               pain        and      discomfort.            CT   scans       show       air      in the       gastric        wall     (arrow).           Best       seen
posteriorly,                 the air is compatible     with emphysematous                                                 gastritis. Endoscopy       demonstrated     massive    infarction     of
the entire                posterior    wall of the stomach.       (33) Gastric                                          emphysema       in a 47-year-old      man with a history     of chronic
myebocytic                  leukemia    and a recently     placed    gastrostomy                                           tube. CT scans show air in the gastric          wall without      cvi-
dence  of perforation                            or contrast  material                           extravasation.     These   changes                        are consistent                 with     gastric    emphysema
and were thought                              to be due to placement                              of the gastrostomy      tube. The                        patient    was             treated      conservatively       and
did      well.




.        Emphysematous                                        Gastritis                   and          Gas-                      sematous                 gastritis.             Emphysematous                       gastritis           can
tric        Emphysema                                                                                                            be caused                 by ingestion                  of toxic          or caustic              sub-
Air       in the             wall         of the         stomach              can        be       classified                     stances,           alcohol              abuse,          trauma,           gastric           infarc-
as     cystic            pneumatosis,                       interstitial            gastric             em-                      tion,       and     gastroduodenitis.                            The      offending               organ-
physema,                      or emphysematous                               gastritis             (52-54).                      ism       is most           often         Esc/ienichia                 coli.
Emphysematous                                  gastritis,          an infectious                     gastritis,                          Gastric           emphysema                     is a benign              condition
is a life-threatening                                condition               (mortality                rate,                     in which             the        stomach               wall       is not        thickened;
60%-80%)                       caused            by bacterial                 invasion               of the                      however,              thin, linear                   streaks     of air are seen                       in
gastric            wall            with        gas     production.                  The           CT        ap-                  the wall.            The patient                      is usually     asymptomatic,
pearance                     consists            of mottled                 air in the gastric                                   and        the     air      tends          to       resolve        spontaneously
wall with                    associated             thickened                  gastric folds.                      It            over        time         without               bong-term              sequebae.             Cystic
may         be         difficult             to distinguish                   between                 emphy-                     pneumatosis                     is also           a benign             condition.               It is
sematous                     gastritis           and        more           benign              conditions                        typically           an        incidental                fmding          at endoscopy,
solely           on          the     basis         of the          CT      appearance                   (Figs                    CT,       or barium                   study.
32,       33).          Such             differentiation                   is obviously                 impor-
tant       in bight                 of the        high       mortality              rate          of emphy-




September                           1996                                                                                                                               Fishman                 et al          U      RadioGraphics             U   1051
                    Figure           34         Gastric      varices in a 41-year-old                     man with     a history  of hepatitis       C, cirrhosis,                          and bright                   red blood
                    from       the        rectum.       Spiral CT scans acquired                        with water     used for gastric     distention       show                         large varices                    in the gas-
                    tric fundus.             In patients            evaluated          for vascular        disease,   air or water is the agent of choice                                   for stomach                     and bowel
                    opacification.



                    .      Gastric              Varices                                                                      need         to optimize                    CT protocols                        suggests             that          CT
                    Gastric           varices          are more            commonly              seen      and               can        provide               important,               accurate,                   and      detailed
                    easier       to define              with        the      increased    use of spiral                      information                     on     neoplastic                  and         inflammatory                       dis-
                    CT coupled                  with        rapid         injection    of iodinated                          ease.        Although                  classic          upper            gastrointestinal
                    contrast              material          (55)        (Fig 34). Balthazar         et al                    studies             and         endoscopy                play        a major                role      in
                    (55)       describe              gastric        varices        as enhancing,              tubu-          evaluation                  of the          stomach,                CT has              unique             at-
                    bar structures                   most       commonly               seen      in the     fun-             tributes             that        make           it an     ideal          examination.                        In
                    dus      of the          stomach.              Collateral          vessels      are     corn-            the future,     the roles of endoscopic          ultrasound
                    monly            seen       in the         region         of the     gastrohepatic                       (57) and magnetic         resonance      imaging      in evalu-
                    ligament,    near the lesser      omentum,        and along                                              ating the stomach         will need to be ftirther          cx-
                    the course     of the coronary      vein. Associated                                                     plored;     however,     CT is a cost-effective         study
                    esophageal      varices     may also be seen. On non-                                                    and        will       remain              an important                    imaging               tool.
                    enhanced      CT scans or CT scans obtained             with
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1054   U   Scientific       Exhibit                                                                                                                                                     Volume                 16             Number                    5

				
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