Table 1: Imaging modalities for RAI-refractory recurrent disease.

Imaging studyUtilityProsCons

Ultrasound neckDetection of neck diseaseSensitive; ability to biopsyOperator dependent; difficult to detect invasive disease and disease in the posterior neck
CTDetection of local and metastatic diseaseSensitive; less operator dependentRadiation exposure; risk of renal injury with contrast; delays in radioiodine administration
MRIDetection of local and metastatic diseaseSensitive for CNS disease; no radiation exposureDifficult to tolerate in some patients; risk of nephrogenic systemic fibrosis (NSF) in patients with renal failure; contraindicated in patients with certain metal devices or implants
FDG-PET scanDetection of metastatic disease and providing prognostic informationSensitive when used with CTDetects FDG-avid disease only