Radioiodine Hot Hand Sign

Abstract

A 32-year-old woman was referred for a whole body I-131 scan 4 weeks after total thyroidectomy for differentiated thyroid carcinoma. Initial scan 72 hours after administration of 5 mCi of I-131 disclosed no abnormal foci. A post-treatment scan performed 10 days after 150 mCi of I-131 showed abnormal uptake throughout the left chest, suggestive of mediastinal and pulmonary metastases, and tracer activity in both hands. Absence of tracer uptake on pre-treatment scan, along with tracer in hands, alerted staff to possible contamination. Repeat imaging of chest after washing revealed no evidence of abnormal tracer uptake.

Abnormal uptake on pretreatment scan, even if false positive, may lead to erroneous I-131 administration. It is important to be aware of possible contamination, especially when discordant findings exist, as observed in our patient.