Procedure Guideline for Thyroid Scintigraphy : 1.0

David Becker, N. David Charkes, Howard Dworkin, James Hurley, I. Ross McDougall, David Price, Henry Royal and Salil Sarkar New York Hospital-Cornell Medical Center, New York, New York; Temple University Hospital, Philadelphia, Pennsylvania, Philadelphia; Stanford University Medical School, Palo Alto, Cahfornia; University of Cal@fornia Medical Center, San Francisco, Cal@fornia; Mallinckrodt Institute ofRadiology, St. Louis, Missouri; State University ofNew York Health Science Center, Brooklyn, New York; William Beaumont Hospital, Troy, Michigan

Except under very specific circumstances (e.g., for KeyWords:procedureguideline;thyroidscintigraphy determination if a nodule is autonomous), thyroid J NuclMed1996;37:1264-1266 scintigraphy should be delayed for a period long enough to eliminate the effects of these interfering PART I: PURPOSE factors. The purpose of this guideline is to assist nuclear medicine B. Information Pertinent to Performing the Procedure practitioners in recommending, performing, interpreting and 1. Possibility of interfering medications (e.g., thyroid hor reporting the results of thyroid scintigraphy. mone, antithyroid drugs, iodine-containing medications) 2. Prior iodinated contrast PART II:BACKGROUNDINFORMATIONAND 3. Ingestion of iodine-rich foods DEFINITiONS 4. Pertinent laboratory data including results of thyroid Thyroid scintigraphy consists of one or more planar images of function tests the thyroid obtained within 15—30mm after intravenous injec 5. Pregnancy/Lactation/Nursing status tion of [99mTc]pertechnetate or 3—24hr after the oral ingestion 6. Results of prior thyroid imaging tests of radioactive iodine. 7. Results of prior thyroid uptake In this document, hyperthyroidism refers to an excess of 8. Recently administeredradionuclides thyroid hormone due to an overactive thyroid gland as well as C. Precautions due to other causes. None PART III:COMMONINDICATiONS D. Radiopharmaceutical

A. To relate the general structure of the thyroid gland (e.g., Comparison of Radiopharmaceuticals for Thyroid Scintigraphy nodular or diffuse enlargement) to its function. This may be useful in distinguishing Graves' disease from toxic nodular RadionuclideAdvantagesDisadvantages@Tc]pertechnetateLess goiter, a distinction of significance in determining the expensive Trapped but not amount of 1311to be given as therapy for hyperthyroidism. organified

B. To correlate thyroid palpation with scintigraphic findings Morereadilyavailable . @ti@@fty in to determine the degree of function in a clinically defined Morerapid esophagus or area or nodule (i.e., palpable). examination. vascularstructures C. To locate ectopic thyroid tissue (i.e., lingual) or determine can be misleading whether a suspected “thyroglossalduct cyst―is the only . Poor image quality functioning thyroid tissue present. lowr@oiOdideBetter when uptake is D. To assist in evaluation of congenital hypothyroidism. for Higher cost E. To evaluate a neck or substernal mass. Radionuclide visualizationof . May be less scintigraphy may be helpful to confirm that the mass is retrostemalthyrdd convenientfor functioning thyroid tissue. tissue patientas delayed F. To differentiate thyroiditis (i.e., subacute or silent) and Yieldsbetter images imagingat 24 hr is factitious hyperthyroidism from Graves' disease and other when uptake is low. often used forms of hyperthyroidism. . Is less readily available

PART IV: PROCEDURE . Imaging times are generallylonger A. Patient Preparation 1. Avoidance of Interfering Materials The concentration of radioiodine in the thyroid is af 2. Because of the large radiation dose to the thyroid fected by many factors. (approximately 1—3rad/pCi administered), the use of a. Medications such as thyroid hormones and antithy 13 ‘I for thyroid scintigraphy should be discouraged roid agents which affect the pituitary-thyroid axis. except when a treatment with 131! j@planned. b. Iodine-containing food (e.g., kelp) and medications 3. Radiation Dosimetry (see tables on page 1265) (e.g., iodinated contrast, amiodarone, betadine). 4. An intramuscular injection of [99mTc]pertechnetate can also be used when venous access is difficult. ReceiVedApr.19,1996;accepted May6, 1996. For correspondence or reprints contact Wendy Smith, MPH, Society of Nuclear E. Image Acquisition Medicine, 1850 Samu@ Morse Dr., Reston, VA22090. 1. Instrumentation

1264 THEJOURNALOFNUCLEARMEDICINE•Vol. 37 •No. 7 •July 1996 Radiation Dosimetry in Adults 16—24hr have the advantage of lower body back ground but the disadvantage of a lower count rate. AdministeredtheactMty Organ receiving Interpretable images can be obtained as long as 36 hr doseRadiopharmaceutical MBq largest radlationdos& Effective (rem)Nal3ll@iodidet (mCi) mGy(red) mSv after inqestion. @ c. When II is used, the images should be obtained at 1.85-7.46.6Thyro@(0.05-0.2)p.o. 210 16—24hr after ingesting the radioiodine. 4. Acquisition parameters (24.4)Nal@l@iodide* (780) With 9@Tc, an anterior image is acquired for 100,000—200,000counts or 5 mm, whichever occurs 7.5—250.075Thyroid(0.2-0.6)p.o. 1.9 first. With 123! the corresponding parameters are gener (0.278)[@‘TcJpertechnetate@ (7.0) ally 50,000—100,000 counts or 10 mm. Both anterior oblique images should be obtained for the same amount 75—3700.013uu(2-10)i.v. 0.062 of time as the anterior image. The distance between the pinhole aperture and the neck should be adjusted so that (0.048)*Per (0.23) the image of the thyroid occupies the central two-thirds of the field of view. mCi)tICRPMBq @per The thyroid should be palpated with the patient in (2).@1CRP53,page276,assuming15%uptake position for imaging. Radioactive or radiopaque markers (2).@ICRP53, page 264, assuming 15% uptake may be used to identify anatomical landmarks (e.g., (5).uu 53, page 199, no blockingagent thyroid cartilage, sternal notch) and the location of = upperintestine.Radiationlarge palpable nodules. Localizing markers for nodules should be centered in the field of view to avoid parallax. Dosimetryyr)Administeredin ChikJren CAged5 Duplicate views should be obtained without the markers. Size markers should be used with caution since the receivingactivityOrgan pinhole collimator will cause geometric distortion with thelargestMBq/Kg depth. dos&Radiopharmaceutical radiationdose* Effective F. Interventions (rem)Nal3ll@iodidet (mCVKg) mOy(red) mSv Giving the patient water to drink is sometimes useful in 34Thyroid(0.0004-0.0016)0.025-0.1 p.o. 1,100 eliminating esophageal activity. G. Processing (40.7)Na123l-iodide@ (4,070) None H. Interpretation/Reporting 0.35Thyroid(0.003-0.01)0.1-0.3 p.o. 9.8 1. An adequate history and patient examination should be performed to permit appropriate diagnostic evaluation. (1.3)[@“Tc]pertechnetate@ (36.3) 2. The scintigraphic findings should be correlated with the physical examination as to the size, shape and location of 0.04uu(0.015-0.07)1—5i.v. 0.21 the thyroid gland and the size and location of thyroid nodules or neck masses. (0.15)*Per (0.78) 3. The uniformity and intensity (thyroid/background) of uptake and the presence, absence, size and location of mCi)tICRpMBq (per any areas of increased or decreased uptake should be uptake.*ICRP53,page276,assuming15% described. uptake.@ICRP53, page 264, assuming 15% 4. Autonomous hyperfunctioning (hot) nodules are easily agent.uu53, page 199, no blocking = upperlargeintestine. identified by scintigraphy and are rarely malignant. Hypofunctioning nodules represent a nonspecific find ing. The diagnosis of a thyroid nodule is dependent on a. A gamma camera equipped with a pinhole collimator palpatory, not scintigraphic, findings. and an aperture 5 mm or less in diameter is conven tionally used. I. Quality Control Routine quality control for cameras used for imaging, see b. Rectilinear scanning of the thyroid may also be used Society ofNuclear Medicine Procedure Guidelinefor Gen for thyroid imaging. eral Imaging. Compared to gamma cameras, scanners are better able to estimate the size of the thyroid and correlate J. Sources of Error the location (relative to other anatomical landmarks) 1. Local contamination (clothing, skin, hair, collimator, crystal) of thyroid nodules. 2. Patient positioning 2. Esophageal activity (hiatal hernia) The patient should be supine with the neck extended and supported by a pillow placed under the shoulders. In PART V: DISCLAIMER patients who are unable to lie supine, the sitting position The Society of Nuclear Medicine has written and approved may be used. guidelines to promote the cost-effective use of high quality 3. Timing of images nuclear medicine procedures. These generic recommendations a. When [@Tc]pertechnetate is used, imaging should cannot be applied to all patients in all practice settings. The begin 15—30min after injection. guidelines should not be deemed inclusive of all proper proce b. When 123!is used, images can be obtained as early as dures or exclusive of other procedures reasonably directed to 3—4hr after ingesting the tracer. Images obtained at obtaining the same results. The spectrum of patients seen in a

PROCEDURE GUIDELINE FOR THYROID SCINTIGRAPHY •Becker et al. 1265 specialized practice setting may be quite different than the tion dose estimates to normal humans from 99mTc as spectrum ofpatients seen in a more general practice setting. The sodium pertechnetate. JNuclMed 1976; 17(suppl):74— appropriateness of a procedure will depend in part on the 77. prevalence of disease in the patient population. In addition, the resources available to care for patients may vary greatly from Radiation absorbed dose from 99mTc as sodium one medical facility to another. For these reasons, guidelines pertechnetate. cannot be rigidly applied. 6. Mazzaferri EL. Management of a solitary thyroid Advances in medicine occur at a rapid rate. The date of a nodule.N Engi J Med 1993;328:553—559. guideline should always be considered in determining its 7. Sarkar SD, Becker DV. Thyroid uptake and imaging. current applicability. In: Becker KL, editor. Principles and practice of endocrinology and metabolism, 2nd ed. Philadelphia: PART Vi: ISSUES REQUIRING FURThER JB Lippincott;1995:307—313. CLARIFiCAtiON None Comprehensive and up-to-date review of indications, methods and interpretation of thyroid uptake and imaging in benign and PART V1I: CONCISE BIBUOGRAPHY malignant thyroid conditions. I . Beierwaltes WH. Endocrine imaging in the management of goiter and thyroid nodules: part I. J Nucl Med 8. Sostre S, Ashare AB, Quinones JD, et al. Thyroid 1991;32:1455—1461. scintigraphy: pinhole images versus rectilinear scans. Radiology 1978; 129:759 —762. Excellent discussion of the etiopathology of goiter and 9. Verelst J, Chanoine J, Delange F. Radionuclide imag scintigraphic correlates. ing in primary, permanent congenital hypothyroidism. 2. Berman M, Braverman LE, Burke J, et al. MIRD dose ClinNuclMed 1991;16:652—655. estimate report number 5. Radiation absorbed dose One of the more recent articles on pediatric imaging using from 123!l@4I125!126!130!131!and 1321as sodium [@“Tc]pertechnetatein a large series of patients. iodide.J NuciMed 1975;16:857—860. 3. Cavalieri RR, McDougall IR. In vivo isotopictestsand PART Viii: LAST BOARD OF TRUSTEES APPROVAL imaging. In: Braverman LE, Utiger RD, eds. Werner DATE and Ingbar ‘sthe thyroid. Philadelphia: Lippincott; February 12, 1995 1996:inpress. PART IX: NEXT REQUIRED APPROVAL DATE 4. Kusic Z, Becker DV, Sanger EL, et al. Comparison of February 1997 technetium-99m and iodine-123 imaging of thyroid nodules: correlation with pathologic findings. J Nucl ACKNOWLEDGMENTS Med 199031:393—399. We thank Wendy Smith, MPH, Associate Director, Commission Study shows little difference between 99mTc and 123!in quality on Health Care Policy, Society of Nuclear Medicine, for project of images. Discordant nodules are also discussed. coordination, data collection and editing; members ofthe Guideline Development Subcommittee David Brill, MD and Robert Hattner, 5. Lathrop KA, Atkins HL, Berman M, et al. MIRD dose MD who contributed their time and expertise to the development of estimate report number 8. Summary of current radia this information.

Procedure Guideline for Thyroid Uptake Measurement: 1.0

David Becker, N. David Charkes, Howard Dworkin, James Hurley, I. Ross McDougall, David Price, Henry Royal and Salil Sarkar New York Hospital-Cornell Medical Center, New York, New York; Temple University Hospital, Philadelphia, Pennsylvania, Philadelphia; Stanford University Medical School, Palo Alto, Cahfornia; University of Cahfornia Medical Center, San Francisco, Cal@fornia; Mallinckrodt Institute ofRadiology, St. Louis, Missouri; State University ofNew York Health Science Center, Brooklyn, New York; William Beaumont Hospital, Troy, Michigan

PART I: PURPOSE Key Words procedure guidelines; thyroid uptake measurement The purpose of this guideline is to assist nuclear medicine J NuciMed1996 37:1266-1268 practitioners in recommending, performing, interpreting and reporting the results of thyroid uptake measurements.

PART II: BACKGROUND INFORMATION AND DEFINITIONS Thyroid uptake determination is the measurement of the frac Rec@VedApr. 19, 1996; accepted May 6, 1996. For correspondence or reprints contact: Wendy Smith, MPH, Society of Nuclear tion ofan administered amount ofradioactive iodine that accumu Medicine, 1850 Samuel Morse Dr., Reston, VA 22090. lates in the thyroid at selected times following ingestion. Thyroid

1266 THEJOURNALOFNUCLEARMEDICINE•Vol. 37 •No. 7 •July 1996