Table 1.

Imaging modalities for RAI-refractory recurrent disease.

Imaging study	Utility	Pros	Cons
Ultrasound neck	Detection of neck disease	Sensitive; ability to biopsy	Operator dependent; difficult to detect invasive disease and disease in the posterior neck
CT	Detection of local and metastatic disease	Sensitive; less operator dependent	Radiation exposure; risk of renal injury with contrast; delays in radioiodine administration
MRI	Detection of local and metastatic disease	Sensitive for CNS disease; no radiation exposure	Difficult 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 scan	Detection of metastatic disease and providing prognostic information	Sensitive when used with CT	Detects FDG-avid disease only