Ces radiol. 2018, 72(4):263-267 | DOI: 10.55095/CesRadiol2018/036

SPECT/low dose CT detection of the unusual uptake of radioiodine in the rebound thymus after a repeated radioiodine treatment in the young woman with thyroid papillary carcinomaCase report

Jiří Doležal¹, Eva Krčálová¹, Jiří Horáček²

¹ Oddělení nukleární medicíny LF UK a FN, Hradec Králové

² IV. interní hematologická klinika LF UK a FN, Hradec Králové

Aim: To present a rare case report about 31-year-old woman with the positive history papillary thyroid carcinoma and an uncommon rebound thymus uptake of ¹³¹I (radioiodine) on the post-therapy whole body scintigraphy and the chest SPECT/CT imaging after repeated radioiodine treatment.

Method: The thyroid nodule was detected on ultrasound. The papillary thyroid carcinoma was proven by fine needle aspiration biopsy. The woman underwent total thyroidectomy, repeated radioiodine treatments and post-therapy whole body scintigraphies and the chest SPECT/CT imaging. The double-head SPECT/low dose CT multi-imaging scanner Infinia (GE) with infrared body contouring and the large field of view was used. The scanner was fitted with medium-energy, parallel-hole collimators.

Results: The whole body post-therapy scintigraphy and the chest SPECT/CT imaging after the second radioiodine treatment detected focal uptake of radioiodine in the mediastinum, which simulated thyroid cancer metastases. The subsequent SPECT/low dose CT revealed physiologic radioiodine uptake in the rebound thymus gland. The repeated follow-up serum thyreoglobulin marker was negative and excluded metastases in the mediastinum.

Conclusion: unusual radioiodine in rebound thymus can cause the -positive whole body post-treatment scintigraphy and can lead to unnecessary surgery or the next radioiodine treatment.

Keywords: thyroid carcinoma, radioiodine, thymus, SPECT/CT

Grants and funding:

Podpořeno MZ ČR - RVO (FNHK, 00179906).

Accepted: December 15, 2018; Published: December 1, 2018  Show citation