The radioactive handkerchief sign. A contamination artifact in I-131 imaging for metastatic thyroid carcinoma

False-positive findings suggestive of metastatic functioning thyroid carcinoma have been well documented in I-131 whole-body imaging. These artifacts are often associated with contamination from radioiodine-containing body secretions. Recently, a contaminated handkerchief on an iodine-131 whole-body scan was reported. In the following study, two additional cases involving the sequestration of I-131 contaminated handkerchiefs in patients' pockets are presented, and the literature regarding these false-positive findings is reviewed. Although rare, this "radioactive handkerchief sign" may cause serious misinterpretation of a focal radioiodine accumulation.