[Impact of 131I SPECT/CT on the management of differentiated thyroid carcinoma outpatients with radioablation].

OBJECTIVE

The purpose of this study was to comparatively assess the diagnostic accuracy between 131I SPECT/CT and 131I whole-body scintigraphy (WBS) in differentiated thyroid carcinoma outpatients following radioablation.

METHODS

a retrospective cohort study was performed in eleven patients with differentiated thyroid carcinoma (fourteen studies), who underwent both 131I WBS and 131I SPECT/CT, 7-10 days after administration of 1,110 MBq of 131I for radioablation, following a total thyroidectomy. A head and neck surgeon and two nuclear medicine specialists first interpreted the WBS images, followed by SPECT/CT images.

RESULTS

SPECT/CT led to accurate revisions of the first diagnoses in 13 of 24 cervical foci of 131I uptake on WBS. Out of the 5 distant lesions, which were diagnosed as metastases by WBS alone, 5 (100%) were found out to be benign lesions by SPECT/CT. Thus, WBS was prone to be false-positive both in detecting cervical node metastases (13/28, 46.4%) and distant metastases (5/17, 29.4%). Eventually, SPECT/CT after 131I radioablation altered postoperative patients' management in 42.8% of patients with thyroid carcinoma by upstaging or down-staging their disease.

CONCLUSION

SPECT/CT after 131I radioablation for differentiated thyroid cancer patients determines more accurately cervical lymph node metastasis, thyroid remnants and distant metastasis than does WBS alone. Both WBS and SPECT/CT after 131I radioablation are highly recommended for appropriate management of differentiated thyroid cancer patients who have undergone a total thyroidectomy.