I Positron Emission Tomography/Computed Tomography Versus Conventional Radioiodine Imaging in Differentiated Thyroid Cancer: A Review.

Studies report a wide spectrum of I positron emission tomography (PET)/computed tomography (CT) sensitivity and specificity in the detection of differentiated thyroid cancer (DTC) lesions. This study reviews the lesion detection rate of pretherapy I PET/CT in different patient populations and further analyzes the factors necessary for a better detection on I PET/CT. A literature search was performed using multiple different databases (MEDLINE, EMBASE, Northern Lights, and handsearching) covering 1996 to April 2018. Two reviewers reviewed and extracted study data for I, I, and I scans in DTC. This review includes 4 retrospective and 10 prospective studies in which 495 DTC patients underwent I and I imaging; no studies made comparisons with I. In the reports that compared I PET/CT with diagnostic I scans, there were a total of 72 patients in whom 120 lesions were detected on I imaging, whereas only 52 were detected on diagnostic I scans. In publications that compared I with post-therapy I scans in 266 patients, 410 lesions were detected with I PET, whereas 390 were detected on post-therapy I scans. Based on I PET/CT in six studies, TNM staging was revised in 15-21% of patients, and disease management was altered in 5-29% of patients. I PET/CT is able to identify a greater number of foci compared with diagnostic I scans. I PET may have better detection compared with post-therapy I scans in patients who are I therapy naive, have less aggressive pathology, or do not have disseminated lung metastases. Additional metastatic lesion detection by I PET may have a significant clinical impact in the management of patients before I therapy in some patients.