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DIAGNOSTIC RADIOLOGY _ BODY SCANS

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DIAGNOSTIC RADIOLOGY _ BODY SCANS Powered By Docstoc
					DIAGNOSTIC RADIOLOGY
&
BODY SCANS

CHAPTERS 20 & 21
X-RAYS

   Electromagnetic radiation of short
    wavelength.
   Penetrate most substances,
    including tissue.
   Also called ionizing radiation.
   Cause fluorescence (emission of
    light) on photographic plates.
   Harmful, in a dose-dependent
    fashion.
X-RAYS AS A DIAGNOSTIC TOOL
           3 PRIMARY WAYS

   1) Radiography.

   2) Fluoroscopy.

   3) Tomography.
RADIOGRAPHY
   Radiograph = an X-Ray image (picture), or
    what we call “the X-Ray.”
   “Like negatives of photographs.”
   X-Rays that penetrate the tissues and
    reach the film turn the film black. As such:
   AIR = BLACK (ISH)
   FAT = DARK GRAY
   WATER = LIGHTER GRAY
   BONE = WHITE (ISH)
FLUOROSCOPY

   See text. Not recommended
   A real-time X-Ray
   Typically used with dye studies such
    as barium swallow, angiography,
    etc.
   Prolongs radiation exposure.
TOMOGRAPHY

   A tomogram is a radiograph that
    generates cross-sectional images at
    different tissue planes.

   CT = computed tomography, or CAT
    scan = computed axial tomography
    – uses computers, produces digital
    images. (More later)
DIGITAL RADIOGRAPH

   A digital image without film.
   Stored in a computer database.
   Can be accessed by anyone with
    access to the database, can be
    emailed, etc.
   No need to chase down the hard
    copy films.
RADIATION SAFETY

   Exposure is cumulative.
                   RISKS
   1) Genetic damage, cancer.
   2) Sterility.
   3) Alterations in the composition of
    individual cells.
   4) Bone marrow production.
     RADIATION SAFETY

   Occupational exposure to ionizing
    radiation is associated with:
                  1) Leukemia.
                  2) Skin cancer.
   See text re:
   The “rem,” the “rad”, and the “gray.”
   X-Ray exposure is measured in millirads.
RADIATION SAFETY

   3 ways to protect against ionizing
    radiation:
   1) Time - as short as possible.
   2) Distance - as far away as
    possible.
   3) Shielding.
RADIATION SAFETY
   PREGNANCY – potential for
    teratogenesis etc. is highest during
    organogenesis, which occurs during
    the 1st 12 weeks.
   Need to ask about pregnancy.
   In a perfect world, X-Rays would be
    done between menses and
    ovulation.
   Shielding the pelvis advised when
    uncertain.
BODY SCANS

   CT
   MRI
   DEXA
   PET
   SPECT
CT / CAT
   Computed tomography, computerized
    axial tomography.
   Uses X-Rays in a 180° fashion.
   Radiation exposure is “small.”
   Image generated based on amount of
    radiation absorbed.
   Can depict all types of tissues except
    nerves.
CT / CAT
                 ADVANTAGES
   1) Excellent detail.
   2) Quick results.

              DISADVANTAGES
   1) Cost.
   2) Time of exposure to radiation.
CT / CAT
   1st CT developed in 1972 to evaluate
    brain abnormalities.
   Now in widespread use for other organ
    systems.
   USES: evaluation of neoplasms /
    masses, hematomas, abscesses, foreign
    body localization, trauma.
   Quicker than MRI.
MRI
   Magnetic resonance imaging.
   See text for details of the physics
    involved.
   In short, uses radio waves and a
    magnetic field that detects changes in
    absorption of energy by hydrogen ions.
   As such, no radiation exposure.
MRI
                 ADVANTAGES
   1) No radiation exposure. Can be used
    during pregnancy.
   2) Better detail than CT.
   3) Imaging modality of choice for the
    CNS.
               DISADVANTAGES
   1) Cost – 1/3 more than CT.
   2) Takes longer, results not available as
    fast as CT.
→
CIRRHOSIS
STONE RIGHT URETER




         ←
MRI Absolute Contraindications

   Brain Aneurysm Clip
   Implanted neural stimulator
   Implanted cardiac pacemaker or
    defibrillator
   Cochlear implant
   Ocular foreign body (e.g. metal shavings)
   Other implanted medical devices: (e.g.
    Swan Ganz catheter)
   Insulin pump
   Metal shrapnel or bullet.
       MRI Relative Contraindications
   1) Penile and non metallic valve prosthesis
   2) Pregnancy: We try to avoid scanning in the
    first trimester since we are not sure if there are
    any adverse effects to MRI. (Pregnant women
    never receive the contrast agent gadolinium)
   3) Claustrophobic or anxious patients can not
    tolerate the MRI scanner.
   4) Obese patients may not fit into the small
    opening of the scanner. In addition the
    maximum weight that the MRI table can sustain
    is 350 lbs.
DEXA

   Dual Energy X-Ray Absorptiometry.
   The modality of choice for
    measuring bone mineral density
    (BMD) in evaluating osteoporosis.
   Low radiation exposure, quick.
      Dexa T Scores
Normal                       Osteopaenia                     Osteoporosis

A normal bone density is     If the bone mineral density     If the bone mineral
when the T score measures    is measured as a T score        density is measured as a
greater than –1.0 (greater   between –1.0 and –2.5           T score of
than minus 1.0)              (minus 1.0 and minus 2.5)       –2.5 or less
                             this indicates the presence     (minus 2.5 or less)
                             of osteopaenia.                 this indicates the
                             Osteopaenia is not              presence of
                             osteoporosis.                   osteoporosis at the site
                             It does however indicate that   of measurement.
                             there is a reduction in bone
                             mineral density, which is not
                             as severe as osteoporosis.
                             This condition represents an
                             earlier phase of bone mineral
                             density loss in the skeleton.
PET SCAN

   Positron emission tomography.
   The positron is the antiparticle or
    the antimatter counterpart of the
    electron. The positron has an
    electric charge of +1, a spin of 1/2,
    and the same mass as an electron.
    (Wikipedia)
   Measures function rather than
    structure.
       PET SCAN
   Patient is injected with a metabolically active
    biochemical substance, such as glucose, water,
    ammonia, which has been tagged with a
    radioactive isotope that emits a positron.
   Binding of these substances with electrons
    found in the tissue being studied causes
    emission of gamma rays, which are converted
    into color-coded images.
   Degree of gamma ray production reflects
    cellular utilization / metabolism of the tagged
    substance.
PET SCAN
APPLICATIONS OF PET SCANS
   High dollar machine, high dollar
    test.
   Costs 1/3 more than MRI.
   Availability typically limited to
    research institutions, and used
    more as a research tool than a
    diagnostic one.
   Findings of altered metabolic
    function can direct innovations in
    treatment.
APPLICATIONS OF PET SCANS

   Neuroimaging - dementia, stroke,
    epilepsy, Parkinson’s disease.
   Cardiac – to assess myocardial viability.
   Psychiatric – schizophrenia, mood
    disorders, substance abuse.
   See
    http://en.wikipedia.org/wiki/Positron_emi
    ssion_tomography
       SPECT
   Single Photon Emission Computed Tomography
   Uses radiopharmaceuticals labeled with a
    positron-emitting isotope such as Technitium –
    99 (Tc-99m).
   Detects gamma rays emitted by the natural
    radioactive decay of the isotope.
   Degree of gamma ray production reflects more
    the degree of perfusion of the organ being
    studied than its function.
APPLICATIONS OF SPECT SCANS

   Neuroimaging- dementia,
    neoplasms, infection, epilepsy.
   Cardiac- ischemic heart disease.
   Others- thyroid, bone, white cells.
   See:
    http://en.wikipedia.org/wiki/SPECT
63 YOM W/
PROSTATE
CANCER
Tc-99 Scan
FUNCTIONAL MRI
   Measures signal changes in the brain that
    are due to changes in neural activity.
   Increased neural activity → need for
    increased oxygen → increased
    oxygenated hemoglobin as relative to
    deoxygenated hemoglobin.
   Because deoxygenated hemoglobin
    attenuates the MR signal, the vascular
    response leads to a signal increase that is
    related to the neural activity.
FUNCTIONAL MRI

    A fMRI scan showing regions of
    activation in orange, including the
    primary visual cortex.
IMAGES

   Images compliments of the
    Department of Radiology at the
    Uniformed Services University of
    the Health Sciences (USUHS),
    Bethesda, Md.
   See: www.rad.usuhs.edu
THE CHEST X-RAY
   Can be used to assess a wide variety of
    pathologic conditions of the chest: heart,
    lungs, mediastinum, bone, esophagus,
    trachea, diaphragm.
   Such as: infection, tumor, lymphoma,
    foreign bodies, rib fractures, cardiac
    enlargement, presence of free air
    (pneumothorax, pneumomediastinum),
    fluid accumulation (pulmonary edema,
    pleural effusion), changes such as
    sarcoid, amyloid.
THE CHEST X-RAY
   Usually take an AP (antero-posterior), or
    PA (postero-anterior), and a lateral view.
   Can also take an oblique view.
   If known, the part you’re interested in
    should be closest to the film.
   To assess free air or fluid, patients
    position can be manipulated to allow
    gravity to affect layering of the fluid or
    air.
               ←



22 YEAR OLD SMOKER
W/ COUGH, WHEEZING
           ←



22 YEAR OLD SMOKER W/
COUGH, WHEEZING
          ← CYSTIC
               TERATOMA




22 YEAR OLD SMOKER W/
COUGH, WHEEZING
                 ←
                 ←




46 YOF W/ CHEST PAIN
AFTER A ROUND OF GOLF
  →               ←




22 YOM W/ NIGHT
SWEATS, WT LOSS
       ABDOMINAL X-RAYS
   The “flat plate,” or scout film, done as
    the sole diagnostic film or prior to a
    contrast study.
   Manipulation of position of the patient
    can assess presence of free air (under
    the diaphragm), fluid, or the presence of
    “air-fluid levels” as seen in bowel
    obstruction.
   KUB- kidneys, ureter, bladder. Term
    used interchangeably w/ flat plate.
  AIR-FLUID
  LEVELS IN
   BOWEL
OBSTRUCTION
43 YOF W/
ABDOMINAL
PAIN
32 YOF W/
G. E.
REFLUX
32 YOF W/
REFLUX
32 YOF W/
REFLUX
32 YOF W/
REFLUX
SKELETAL X-RAYS

   Most useful in assessing fractures,
    but also good for: joint dislocation /
    subluxation, changes in bone
    architecture (erosions, thickening,
    density), presence of abnormal
    calcifications / deposits
    (osteophytes, tophi), etc
18 YOM W/
RIGHT THIGH
PAIN
18 YOM W/
RIGHT THIGH
PAIN
OSTEOSARCOMA
53 YOM W/
SWELLING, LEFT
MIDDLE FINGER
TOPHACEOUS
GOUT   →
18 YOM FELT
 SOMETHING
 “POP” WHEN
THROWING A
SPLIT-FINGER
  FASTBALL
 UNICAMERAL
BONE CYST W/
 PATHOLOGIC
  FRACTURE
MAMMOGRAPHY
   Radiographic images of the breast,
    primarily for early detection of breast
    cancer, prior to the appearance of a
    palpable mass.
   Also useful for evaluation of palpable
    masses: benign neoplasms, fibrocystic
    breast disease, etc.
   Used as an aid in placement of the biopsy
    needle.
SCREENING MAMMOGRAPHY
   For early detection of breast cancer.
   Guidelines as to who, when, and how
    often vary by organization, and depend
    on the patients risk status.
   American Cancer Society: baseline
    between 35 and 40, every 1-2 years
    between 40-50, and yearly after 50,
    along with monthly self-breast
    examination and annual physical exam.
SCREENING MAMMOGRAPHY


                 ↓
CONTRAST STUDIES

   Involves the introduction of a
    radiopaque substance (barium, dye,
    etc) into an organ, vessel, duct, etc
   Allows for the identification of the
    anatomy of the structure being
    studied, its shape, contour, size,
    etc.
   “Filling defect” – describes an area
    where dye should be but isn’t.
       CONTRAST STUDIES
   Barium swallow, upper GI, small bowel series.
   Barium enema (B.E.)
   Oral cholecystograms (OCG).
   Cholangiograms.
   Intravenous pyelogram (IVP).
   Angiograms- arteriograms, venograms.
   Lymphangiograms.
   Hysterosalpingograms (HSG).
   Myelograms.
   Arthrograms.
                             AIR-CONTRAST B.E.


“APPLE CORE” LESION OF
ADVANCED COLON CANCER




                         →   ←
ACHALASIA
2 DAY OLD INFANT W/ INCREASING ABDOMINAL
DISTENTION
2 DAY OLD INFANT W/ INCREASING ABDOMINAL
DISTENTION
16 YOF W/ RLQ PAIN




          ←
16 YOF W/ RLQ PAIN



           ↓
    HSG
BICORNUATE
  UTERUS
 30 YOF W/
NEW ONSET
 SEIZURES
ANGIOGRAM

MENINGIOMA
 ANGIOGRAM
  19 YOF W/
HYPERTENSION
  RENAL
 ARTERY
STENOSIS

				
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