Five months’ follow-up of patients with and without iodine-positive lymph node metastases of thyroid carcinoma as disclosed by 131I-SPECT/CT at the first radioablation.

In differentiated thyroid carcinoma (DTC), 131I-SPECT/CT is more accurate in identifying radioiodine-positive lymph node metastases (LNM) than planar whole-body scans (WBS). The purpose of this study was to investigate the value of 131I-SPECT/CT performed at the first radioablation to predict the occurrence and/or persistence of cervical radioiodine-positive LNM 5 months later. The study included 81 DTC patients that had had SPECT/ spiral CT after radioablation of thyroid remnants after thyroidectomy. The patients were re-examined 5 months later using 131I-WBS performed at TSH stimulation. In addition, SPECT/CT of the neck was performed in patients with iodine-positive cervical foci to distinguish between thyroid remnant and LNM. The outcome variable of the study was the detection or exclusion of iodine-positive cervical LNM. Of 61 patients without a SPECT/CT diagnosis of 131I-positive LNM at radioablation, 60 had no 131I-positive LNM at follow-up. In the remaining patient of this group, a new radioiodine-positive LNM was detected. In 17 of 20 patients with a SPECT/CT diagnosis of 131I-positive LNM ( n = 19) or an indeterminate lesion ( n = 1) at first radioablation, no 131I-positive LNM were detected 5 months later. Radioiodine-positive LNM persisted in three patients of this group. 131I-SPECT/CT has a high negative predictive value with regard to the occurrence of radioiodine-positive cervical LNM 5 months after initial therapy. The majority of iodine-positive LNM diagnosed by SPECT/CT at radioablation disappear within 5 months. These findings motivate further research into the value of 131I-SPECT/CT of the neck for predicting recurrence and planning surgical reintervention in DTC. [ABSTRACT FROM AUTHOR]