131I SPECT/CT in the Follow-up of Differentiated Thyroid Carcinoma: Incremental Value Versus Planar Imaging

Planar 131I scintigraphy is routinely used to detect radioiodine-avid metastases of differentiated thyroid carcinoma (DTC). However, the modality has limitations, such as low sensitivity and lack of anatomic landmarks. We investigated whether SPECT with integrated low-dose CT may have additional value over planar imaging in detecting residue and metastases in DTC patients. Methods: We studied 117 consecutive thyroid-ectomized DTC patients. On 2 different hybrid dual-head g-cameras (55 patients on one camera and 62 on the other), 108 patients underwent 131I diagnostic imaging and SPECT/ CT, and 9 underwent posttherapeutic 131I planar imaging and SPECT/CT. We assigned an incremental value to SPECT/CT when it provided better identification and interpretation of the foci of radioiodine uptake, more correct anatomic localization and characterization, and precise differentiation between tumo