Case Author(s): Jayson R. St. Jacques,M.D. and Barry A. Siegel,M.D. , . Rating: #D2, #Q3

Diagnosis: Metastatic thyroid cancer

Brief history:

31-year-old man post thyroidectomy


Whole-body anterior and posterior images are shown.

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Full history/Diagnosis is available below

Diagnosis: Metastatic thyroid cancer

Full history:

31-year-old man with papillary thyroid carcinoma, status post total thyroidectomy and recent treatment with 100 mCi I-131. These images were obtained 120 hours after the therapeutic dose of I-131.


100 mCi I-131 sodium iodide p.o.


There is intense activity of I-131 within the thyroid bed (with "star effect" because of collimator septal penetration). There also is I-131 uptake in adjacent cervical lymph node and in multiple bilateral pulmonary metastases.


There is expected I-131 activity in the salivary glands, stomach, colon, and urinary bladder.


Follow-up chest CT performed 20 days later demonstated no pulmonary nodules to suggest metastatic disease.

Major teaching point(s):

Whole-body imaging after a therapeutic dose of I-131 is the most sensitive means for localizing residual, recurrent or metastatic thyroid cancer, for those tumor types that are typically iodine avid (follicular and papillary carcinomas). Diagnostic I-131 imaging studies obtained after administration of 2-5 mCi are less sensitive because they are realtively counted limited.

Before administration of I-131 for therapeutic purposes, it is essential that the endogenous TSH level be elevated (a value exceeding 30 uIU/mL is generally recommended. It also is important to ascertain that the patient has not recently received iodine from dietary sources (such as kelp/seaweed), iodinated contrast agents, or medications (amiodarone, cough suppressants).

Detection by I-131 imaging of pulmonary metastases that are not apparent on chest radiography or CT is unusual, but well documented.

ACR Codes and Keywords:

References and General Discussion of Thyroid Scintigraphy (Anatomic field:Face, Mastoids, and Neck, Category:Neoplasm, Neoplastic-like condition)

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Case number: tr013

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