Objective: Whole-body I-131 scanning (WBS) is a standard method in the evaluation of patients with differentiated thyroid carcinoma (DTC). However, it has some limitations in terms of distinguishing between physiological and pathological tracer uptake and in defining the exact anatomical location of pathological foci. The purpose of our study was to determine the additional diagnostic value of SPECT/CT imaging in patients with DTC.
Materials and Methods: A total of 142 patients, each with a history of previous total thyroidectomy and who had undergone diagnostic or post-therapeutic WB imaging, were included in this retrospective study. The distinction between physiological and pathological uptake could not be clearly established and/or the localization of pathological uptake could not be clearly defined on the WBS, both of which were considered inconclusive findings. Subsequently, the regional SPECT/CT images of these patients were evaluated.
Results: The number of pathological foci detected by WBS and SPECT/CT was 64 and 59, respectively. The exact anatomical localization was determined in 85.9% of the lesions with SPECT/CT. Benign accumulations (inflammatory/physiological) were determined in 12.5% of inconclusive foci. In 14.1% of WBS-detected foci, no significant tracer uptake was observed on the SPECT/CT images. Four additional foci were detected on SPECT/CT (3 thyroid remnants, 1 bone remnant).
Conclusion: SPECT/CT improves the specificity of I-131 scanning and contributes to the management of DTC patients.