Unusual patterns of I-131 contamination

Abstract

Whole body imaging with radioiodine can detect functioning metastases, which can often be effectively treated with appropriate amounts of radioiodine. Non-physiologic I-131 uptake detected on images is usually interpreted as suggesting functioning thyroid metastases. However, extra-thyroidal I-131 accumulation does not always imply thyroid cancer metastases and has been reported on many occasions, including various non-thyroidal neoplasms, and contamination by body secretions. In order to avoid unnecessary therapeutic interventions it is extremely important to properly distinguish false-positive sites of I-131 localization. Three patients with unusual radioiodine contamination patterns, either presented for the first time or rarely presented in the existing literature, were reported. Reported cases consist of contamination in hair (due to styling hair with sputum), contamination in neck (due to drooling during sleep) and, contaminated chewing gum. False positive contamination sources were clarified by careful examination of patients and further images when necessary.

Hair Artifact on the Left Side of Head Mimicking Metastasis of Thyroid Carcinoma in a Woman after I-131 Therapy

“…Unlike those described previously [10,11,[14][15][16] , hair contamination in our case showed an intense activity on the unilateral head. As no other contamination was found in other parts of the body, we extrapolated it originating from nocturnal drooling, which has been reported to result in contamination in neck [11] and shoulder [17] . As the woman had short hair and preferentially slept with head turning left, drooling during sleep induced left-side hair contamination, resulting in an intense activity in left lateral head on the scan, which has been rarely reported.…”

“…Judging from the position and number of the artifact, we deduced that the hair contamination was from saliva instead of urine. Saliva contamination has been reported in hair [10] , neck and thoracic region [11,12] , right buccal area because of chewing gun [11] , base of the neck from contaminated necklace [13] , and so on. Unlike those described previously [10,11,[14][15][16] , hair contamination in our case showed an intense activity on the unilateral head.…”

“…Saliva contamination has been reported in hair [10] , neck and thoracic region [11,12] , right buccal area because of chewing gun [11] , base of the neck from contaminated necklace [13] , and so on. Unlike those described previously [10,11,[14][15][16] , hair contamination in our case showed an intense activity on the unilateral head. As no other contamination was found in other parts of the body, we extrapolated it originating from nocturnal drooling, which has been reported to result in contamination in neck [11] and shoulder [17] .…”

Abnormal right lower abdominal focal retention in the radioiodine (131I) whole-body scan

“…Radioiodine uptake in the salivary glands, oropharynx, nasopharynx, oesophagus, stomach, gastrointestinal tracts and urinary tracts should be acknowledged as physiological 7,8 . Ash et al 9 reported that, the intense uptake along the periphery of the skull can be a physiologic variant.…”

Physiologic and False Positive Pathologic Uptakes on Radioiodine Whole Body Scan

“…(Ozguven, Ilgan et al 2004) Physiologic radioiodine accumulation is related to the expression of the NIS and metabolism related to or the retention of excreted iodine. (Bakheet, Hammami et al 2000;Ahn, Lee et al 2011) Uptake of radioiodine in the thyroid tissue, salivary gland, stomach, lacrimal sac, nasolacrimal duct and choroid plexus is related to the NIS expression of the cells of the organs.…”