Society of Nuclear Medicine Procedure Guideline for Scintigraphy for by broverya73


									Society of Nuclear Medicine Procedure Guideline
for Scintigraphy for Differentiated Papillary and
Follicular Thyroid Cancer
Authors: Edward B. Silberstein, MD, Chair (University of Cincinnati Medical Center, Cincinnati, OH); Abass
Alavi, MD (Hospital of the University of Pennsylvania, Philadelphia, PA); Helena R. Balon, MD (William Beau-
mont Hospital, Royal Oak, MI); David Becker, MD (Weill Cornell Medical School, New York, NY); N. David
Charkes, MD (Temple University Hospital, Philadelphia, PA); Susan E.M. Clarke, MD (Guy’s and St. Thomas
NHS Foundation Trust, School of Medicine, King’s College, London); Chaitanya R. Divgi, MD (Hospital of the
University of Pennsylvania, Philadelphia, PA); Kevin J. Donohoe, MD (Beth Israel Deaconess Medical Center,
Boston, MA); Dominique Delbeke, M.D, PhD (Vanderbilt University Medical Center, Nashville, TN); Stanley J.
Goldsmith, MD (Weill Cornell Medical Center, New York, NY); Donald A. Meier, MD (William Beaumont Hospi-
tal, Royal Oak, MI); Salil D. Sarkar, MD (Jacobi Medical Center, North Bronx Healthcare Network, Bronx, NY);
Alan D. Waxman, MD (Cedars Sinai Medical Center, Los Angeles, CA)

I.   Purpose                                                            III. Examples of Clinical or Research
     The purpose of this guideline is to assist nuclear
     medicine practitioners in recommending, perform-                         To determine the presence and extent of residual
     ing, interpreting, and reporting the results of ex-                      functioning thyroid tissue shortly post-thyroid-
     tended scintigraphy for differentiated thyroid cancer.                   ectomy and, after 131I ablation, to detect the pres-
                                                                              ence and location of functioning thyroid cancer,
                                                                              recurrences and/or metastases.
II. Background Information and Definitions
     Scintigraphy for detection of thyroid metastasis                   IV. Procedure
     and/or residual functioning thyroid tissue consists of
     obtaining images of the body, 1–3 d following the                        The patient should be seen by the nuclear medicine
     oral ingestion of 131I, or 6–48 h after 123I (recogniz-                  physician sufficiently early to ensure the appropri-
     ing that the longer time period will require higher                      ate diagnosis has been made, the patient is suitable
     dosages of 123I). 18F-FDG PET may be helpful for                         for scintigraphy, the necessary laboratory studies
     patients with a rising serum thyroglobulin and nega-                     have been obtained, and low-iodine diet instruc-
     tive or minimal iodine uptake. Other radiopharma-                        tions have been given. This initial appointment is
     ceuticals such as 201Tl and 99mTc sestamibi may also                     important for establishing the doctor/patient rela-
     provide useful information.                                              tionship.

 The Society of Nuclear Medicine (SNM) has written and approved these guidelines as an educational tool designed to promote the cost-
 effective use of high-quality nuclear medicine procedures or in the conduct of research and to assist practitioners in providing appropriate
 care for patients. The guidelines should not be deemed inclusive of all proper procedures nor exclusive of other procedures reasonably
 directed to obtaining the same results. They are neither inflexible rules nor requirements of practice and are not intended nor should they
 be used to establish a legal standard of care. For these reasons, SNM cautions against the use of these guidelines in litigation in which the
 clinical decisions of a practitioner are called into question.
 The ultimate judgment about the propriety of any specific procedure or course of action must be made by the physician when considering
 the circumstances presented. Thus, an approach that differs from the guidelines is not necessarily below the standard of care. A conscien-
 tious practitioner may responsibly adopt a course of action different from that set forth in the guidelines when, in his or her reasonable
 judgment, such course of action is indicated by the condition of the patient, limitations on available resources, or advances in knowledge
 or technology subsequent to publication of the guidelines.
 All that should be expected is that the practitioner will follow a reasonable course of action based on current knowledge, available re-
 sources, and the needs of the patient to deliver effective and safe medical care. The sole purpose of these guidelines is to assist practitio-
 ners in achieving this objective.
 Advances in medicine occur at a rapid rate. The date of a guideline should always be considered in determining its current applicability.

    A. Patient Preparation                                     4. The sensitivity of whole-body scintigraphy
       1. Avoidance of interfering materials                        can be improved if the patient follows a strict
          The concentration of radioiodine in func-                 low-iodine diet starting 7–14 d prior to ad-
          tioning thyroid tissue is affected by many                ministration of the radioiodine tracer and
          factors such as:                                          continuing throughout the period of imag-
          a. Medications, especially thyroid hormones.              ing (and for a day or so after treatment).
          b. Iodine-containing food (eg, kelp) and          B. Information Pertinent to Performing the
              medications (eg, iodinated contrast,             Procedure
              amiodarone, betadine). Imaging should            1. Compliance with a low-iodine diet
              be delayed for a period long enough to           2. TSH level
              eliminate the effects of these interfering       3. History of thyroid hormone withdrawal or
              factors. A low-iodine diet is followed                utilization of rhTSH.
              for 7–14 d before the radioiodine is             4. Serum thyroglobulin and anti-thyroglobulin
              given, as it significantly increases the              antibody levels.
              uptake of radioiodine by functioning             5. Description of operative procedure (extent
              thyroid tissue. The goal is a 24-h urine              of thyroidectomy) and detailed pathologic
              iodine output of about 50 mcg, but this               findings
              measurement is not felt to be necessary          6. Tumor histology, including presence or ab-
              in most cases.                                        sence of capsular and/or vascular invasion
       2. The sensitivity of whole-body scintigraphy                and lymph node involvement
          for detection of functioning metastases can          7. Results of other imaging procedures
          be optimized at TSH levels of 30 mIU/L or            8. Physical examination findings
          more. This is achieved by the administra-            9. History of prior 131I treatment
          tion of recombinant human TSH (rhTSH,                10. Results of prior radioiodine scintigraphy
          Thyrogen®, given as two injections of 0.9            11. History of prior administration of iodinated
          mg intramuscularly on each of two consecu-                contrast (especially as part of a CT exami-
          tive days, with 4 mCi of 131I given the next              nation) or iodine-containing drugs (eg,
          day, TSH and serum tg obtained 2 d after                  amiodarone)
          the oral 131I), or, in the near athyreotic pa-       12. Menstrual history/pregnancy test
          tient, by withdrawing replacement thyroid            13. Nursing/lactation history
          hormone therapy for 3–4 weeks. The patient           14. Surgeon performing the thyroidectomy has
          should be informed of the potential side ef-              sufficient and ongoing expertise in perform-
          fects of rhTSH injection, and of hypothy-                 ing this procedure.
          roidism, if this latter course is taken. In or-   C. Precautions
          der to avoid severely symptomatic, pro-              Patients receiving more than about 5–7 mCi of
          longed hypothyroidism, patients may be                   I should follow the same precautions as pa-
          maintained on triiodothyronine (T3) until            tients treated with 131I for hyperthyroidism.
          10–14 d prior to administration of the ra-        D. Radiopharmaceuticals
          dioiodine. rhTSH will be required if the pa-         1. Oral 131I is administered in activities of 1–5
          tient cannot be prepared by near-total thy-               mCi or less, with many preferring a range
          roidectomy, in the presence of sufficient                 of 1–2 mCi because of data suggesting that
          functioning tumor to suppress endogenous                  stunning (decreased uptake of the therapy
          TSH, or with pituitary insufficiency or iso-              dose of 131I by residual functioning thyroid
          lated TSH deficiency.                                     tissue or tumor due to cell death or dysfunc-
       3. Serum TSH level should be measured 1–3                    tion caused by the activity administered for
          d prior to radioiodine administration. The                diagnostic imaging) is less likely at the
          TSH level should be greater than about 30                 lower activity range. However, stunning
          mIU/L, unless there is significant residual               may not influence the outcome of treatment.
          functioning thyroid tissue that will prevent              With higher dosages, detection of more io-
          an endogenous TSH elevation. Concomi-                     dine concentrating tissue has been reported.
          tant serum thyroglobulin and anti-thyro-             2. Oral 123I may be administered at a dosage
          globulin antibody assays should be ob-                    typically between 0.4–5.0 mCi, which may
          tained.                                                   avoid stunning.
                                                              SCINTIGRAPHY FOR DIFFERENTIATED THYROID CANCER                     3

       3. Positron emission tomography with 18F-FDG                    E. Image Acquisition
          may be used to identify tumors that are not                     1. Instrumentation
          visualized with radioiodine. While these tu-                       For 131I, a large-field-of-view camera and a
          mors are less likely to respond to 131I treat-                     high-energy parallel hole collimator is used.
          ment, they may be amenable to surgical resec-                      For 123I, 201Tl and 99mTc, a low-energy col-
          tion, external radiation or embolization. Tu-                      limator and a large-field-of-view camera are
          mors that are radioiodine-negative and FDG-                        preferred. PET/CT scanning will provide
          positive are associated with a less favorable                      the optimal imaging when 18F-FDG is em-
          prognosis. Imaging with FDG is more sensi-                         ployed. If PET/CT is performed, refrain
          tive when the serum TSH level is elevated,                         from using oral or intravenous iodinated
          which can be achieved with rhTSH or, less                          contrast agents, as this will impact potential
          quickly, with thyroid hormone withdrawal.                             I treatment.
             Tc-sestamibi, preferably with SPECT, may                     2. Patient positioning
          be used to image radioiodine-negative metas-                       Lying supine on an imaging table.
          tases if FDG–PET is not available. 201Tl is un-                 3. Imaging protocols
          commonly used for this purpose today.                              a. Post-thyroidectomy, pre-ablation choices:

                                         Radiation Dosimetry for Adults
     Radiopharmaceuticals                   Administered               Organ Receiving the                   Effective Dose
                                              Activity                Largest Radiation Dose

                                                 MBq                         mGy/MBq                           mSv/MBq
                                                (mCi)                         (rad/mCi)                        (rem/mCi)
          F-fluorodeoxyglucosea                370–740                           0.16                             0.019
                                                                             bladder wall
                                               (10–20)                          (0.59)                            (0.07)
           123       b
     Na I iodide                             14.8–185 po                         0.09                              0.013
     (0% thyroid uptake)                                                     bladder wall
                                              (0.4–5.0)c                        (0.33)                            (0.048)
     Na131I iodideb                             37–185                           0.81                              0.11
     (0% thyroid uptake)                                                     bladder wall
                                                (1–5)c                           (3.0)                            (0.41)
     201             b
           Tl chloride                       110–185 iv                          0.4 6                             0.16
                                                 (3–5)                          (1.70)                             (0.60)
           Tc sestamibib                     370–740 iv                          0.050                             0.015
                                                                         upper large intestine
                                               (10–20)                         (0.185)                            (0.056)

a. Delbeke D, Coleman RE, Guiberteau MJ, et al. Procedure guideline for tumor imaging with 18F-FDG PET/CT 1.0. J Nucl Med

b. International Commission on Radiological Protection. Radiation Doses to Patients from Radiopharmaceuticals. Oxford: Perga-
   mon Press, 1988.

c. In general the larger activity of radioiodine one administers, the higher the scan sensitivity for metastatic thyroid cancer. This
   must be balanced with the apparent “stunning” effect described for both 123I and 131I at higher dosages, although the effect this
   stunning has on eventual outcome is unclear and may be minimal. The ranges for diagnostic dosages of radioiodine given in the
   table are wide, but all have been used successfully by thyroid cancer consultants. 4 mCi of 131I are recommended by the manu-
   facturer if rhTSH is employed.

           i. rhTSH may be used to elevate the                               tion if regional or distant metas-
                serum TSH for post-operative pre-                            tases are detected on the pre-
                ablative scanning with either 123I or                        ablation scan.
                    I (dosages in table above) prior to            iv. Post-131I ablation scintigraphy is rec-
                    I therapeutic ablation. This is an                  ommended 4–10 d after administering
                “off-label” indication for rhTSH (not                   the ablative dosage, as this provides
                in the FDA package insert), but em-                     enhanced sensitivity over all the pre-
                ployed by a number of consultants.                      ablative imaging procedures noted
           ii. Using endogenous TSH stimulation,                        above. SPECT or SPECT/CT may
                the patient may be allowed to be-                       improve tissue/tumor localization.
                come        hypothyroid,     minimizing         b. Post-thyroidectomy, post-ablation imag-
                symptoms by checking the patient’s                 ing for restaging 6–12 months (and
                blood as early as three weeks post-                later) post-ablation.
                thyroidectomy for the desired TSH                  i. 1–5 mCi of 131I with scanning at 1–3
                level (>30 mIU/L) to optimize scan                      d (daily scanning required if quanti-
                sensitivity.                                            tative dosimetry is employed).
           iii. The American Thyroid Association                   ii. rhTSH protocol if likelihood of 131I
                Guideline suggests not imaging be-                      therapy is low or intermediate.
                fore 131I therapy. Nuclear medicine                iii. Endogenous TSH stimulation if
                consultants are divided as to the need                  probability of 131I therapy is high;
                for thyroid imaging before 131I abla-                   some consultants are now employing
                tion, but one must recognize the low                    rhTSH “off label” successfully for
                but finite frequency of significant                     this therapeutic purpose.
                clinical problems such scanning can             c. 18F-FDG
                uncover, including the following:                  i. Indication: rising serum thyroglobu-
                (a) About 1% of the time the thyroi-                    lin with one post-131I therapy scan
                     dectomy is truly total, and, if there              negative.
                     are no remnants to be ablated,                     (a) When there is a suspicion that
                     then giving 131I would achieve no                       the 131I scan will be negative or
                     purpose, although in high-risk pa-                      have low sensitivity, some con-
                     tients treatment of occult metasta-                     sultants recommend simultane-
                     ses may be warranted.                                   ously performing a 18F-FDG
                (b) If too large a thyroid remnant                           scan (the sensitivity of which is
                     remains post-operatively, and                           higher when the serum TSH is
                     one is unaware of this, then the                        elevated) after rhTSH stimula-
                     usual ablative dose, ranging from                       tion, on the Wednesday (day 3)
                     about 75–150 mCi of 131I, might                         following rhTSH injections on
                     uncommonly cause radiation thy-                         days 1 and 2, then the 131I scan
                     roiditis with clinically significant                    on day 5, Friday, This saves the
                     neck pain and swelling.                                 cost and inconvenience of two
                (c) Distant metastases in the brain or                       sets of rhTSH injections. Simul-
                     spinal cord might require pre-                          taneous 18F-FDG and 131I im-
                     radiation corticosteroids to avoid                      aging are also possible after thy-
                     complications caused by radia-                          roid hormone withdrawal with
                     tion-induced swelling.                                  resultant TSH elevation.
                (d) At some institutions, large thy-               ii. Patient preparation requires 2 d of
                     roid remnants, especially in high                  rhTSH injection to optimize sensitiv-
                     risk patients, are removed with a                  ity.
                     second thyroidectomy before             4. Timing of the Images
                     high dosage 131I can be given,             a. For 131I, images are obtained 1–3 d after
                     as lower dosages of 131I may                  the radiopharmaceutical administration.
                     fail to ablate large remnants.                Later images, when background is di-
                (e) Larger dosages of radioiodine are              minished, often provide better definition
                     usually given at the time of abla-            of low-activity lesions. Imaging 4–10 d
                                                         SCINTIGRAPHY FOR DIFFERENTIATED THYROID CANCER            5

          after a therapeutic dose of 131I can be              G. Processing
          helpful in demonstrating small or func-                 None
          tioning metastases not visible with the              H. Interpretation Criteria
          low scanning dose.                                      An adequate physical examination and history
       b. For 123I, images are obtained 6–48 h fol-               should be obtained. The presence of palpable
          lowing the administration of the radio-                 tissue in the neck should be defined for correla-
          pharmaceutical, recognizing that higher                 tion with the scintigraphic findings.
          dosages will be necessary for the longer                     Special attention should be paid to the pre-
          time period.                                            cise placement of markers on anatomical land-
       c. For 18F-FDG, images are begun 60–90                     marks. For appropriate interpretation of anterior
          min following injection.                                thyroid bed findings, it is necessary to be certain
       d. For 99mTc sestamibi and 201Tl, images                   of the location of the nose and/or mouth, thyroid
          are obtained 15 min after administration                cartilage and sternal notch in the neck. For
          of the radiopharmaceutical. SPECT may                   whole-body imaging, other landmarks may be
          be more accurate for localization of ab-                important such as costal margins, xyphoid proc-
          normalities.                                            ess, pubic symphysis, and iliac crests. Posteri-
   5. Image Acquisition (all tracers)                             orly, the location of the spine, iliac crests, etc,
       a. Anterior and posterior images from the                  can be identified and transferred to the film. In
          top of the skull through the femurs are                 addition to the scintigraphic images with mark-
          obtained. Spot images should be ob-                     ers, duplicate images should be obtained without
          tained for approximately 10–15 min per                  the markers to avoid interference with areas of
          view. Longer imaging times may be                       uptake adjacent to the markers.
          helpful for images obtained more than                I. Reporting
          3 d after administration of the radioio-                The report should include a qualitative estimate
          dine.                                                   of the size, activity and location of any areas of
       b. If images are obtained with a whole-                    uptake that correspond to any functioning nor-
          body scanner, the scan speed should be                  mal or abnormal thyroid tissue. Particular atten-
          adjusted so that whole body imaging                     tion should be paid to activity in the thyroid
          takes approximately 40 min per pass or                  bed. Scan images cannot differentiate residual
          4–5 cm/min for a dosage of 4 mCi 131I,                  normal thyroid tissue (ie, thyroid remnants)
          using a high-energy collimator.                         from tumor there. Comparison with prior scans
       c. Pinhole images of the neck for single                   can often be useful in defining the significance
          photon emitters, in combination with                    of localized neck activity. Lateral and oblique
          adequate anatomic markers and careful                   views may be useful in separating thyroid bed
          palpation, may be effective in differenti-              activity from neighboring lymph node activity.
          ating between normal residual thyroid tis-                   Results of recent thyroglobulin assays may
          sue, salivary gland uptake, residual thy-               be useful, especially in interpreting negative
          roid cancer, and lymph node metastasis,                 scintigraphic finding, recognizing that about
          but this is often a difficult determination.            20% of patients with thyroid cancer have anti-
          SPECT/CT with 131I may occasionally be                  bodies to thyroglobulin, which invalidate the
          helpful in this distinction.                            serum thyroglobulin measurement.
       d. 24-h neck iodine uptake measurements                 J. Quality Control
          are often helpful in determining the mass               See Society of Nuclear Medicine Guideline on
          of remaining thyroid tissue or tumor.                   General Imaging.
       e. SPECT or SPECT/CT may be helpful to                  K. Sources of Error
          improve tissue localization                             1. Local contamination (clothing, skin, hair,
F. Interventions                                                      collimator, imaging table)
   Giving the patient an apple or crackers to chew                2. Esophageal activity
   and swallow is more useful than a drink of wa-                 3. Asymmetric salivary gland uptake
   ter to eliminate common artifacts from mouth                   4 Breast uptake
   and esophageal activity.                                       5. Thymus uptake

V. Issues Requiring Further Clarification                  E. Iwata M, Kasagi K, Misaki T et al. Comparison
                                                              of whole-body 18F-FDG PET, 99mTc-MIBI
    A. What is the best dose of 131I for whole-body           SPET, and post-therapeutic 131I-Na scintigra-
       imaging that would provide the most diagnostic         phy in the detection of metastatic thyroid can-
       information with minimal stunning (see section         cer. Eur J Nucl Med Mol Imaging
       IV.D.1. above) both in the initial work-up and         2004;31:491–498.
       to detect recurrences?                              F. Lakshmanan M, Schaffer A, Robbins J, et al. A
    B. What are the detrimental long term affects, if         simplified low-iodine diet in I-1 scanning and
       any, of thyroidal stunning?                            therapy of thyroid cancer. Clin Nucl Med
    C. What is the role, and adequate minimal dosage,         1988;13:866–868.
       of 123I in whole-body surveys post-thyroid-         G. Palmedo H, Bucerius J, Joe A. Integrated
       ectomy and pre-ablation, and possibly for me-          PET/CT in the differentiated thyroid cancer:
       tastatic disease, compared to 131I?                    Diagnostic accuracy and impact on patient
    D. Does lithium administration promote retention          management. J Nucl Med 2006;47:616–624.
       of radioiodine in metastatic foci sufficiently to   H. Park HM, Park YH, Zhou XH. Detection of
       be of therapeutic value?                               thyroid remnant/metastases without stunning:
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       surgery and before ablation?                        I. Plotkin M, Hautzel H, Krause BJ, et al. Impli-
    F. What is the role of somatostatin receptor agents       cation of 2-18fluoro-2-deoxyglucose positron
       in detecting thyroid cancer when the serum thy-        emission tomography in the follow-up of
       roglobulin is elevated but the 131I and 18F-FDG        Hurthle cell thyroid cancer. Thyroid 2002;12:
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    G. Does the sensitive serum thyroglobulin assay        J. Sarkar SD, Kalapparambath TP, Palestro CJ.
       allow the nuclear medicine physician to use            Comparison of 123I and 131I for whole-body im-
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       lower than one would see using 5 mCi?                  cal utility of post-treatment radioiodine scans
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       and serum thyroglobulin are negative in a high-        629–634.
       risk patient?                                       L. Shiga T, Tsukamoto E Nakada K, et al. Com-
                                                              parison of 18F-FDG, 131I-Na, and 201Tl in diag-
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