Background: The aim of this study was to evaluate post-therapy iodine-131 single-photon emission computed tomography/computed tomography (131I-SPECT/CT) imaging in comparison to conventional planar 131I whole-body imaging, and to assess its clinical impact on the management of patients. Methods: We retrospectively reviewed planar 131I whole-body and 131I-SPECT/CT imaging findings in 67 patients who underwent 131I therapy for thyroid cancer. Two nuclear medicine physicians reviewed the scans independently. The foci of increased tracer uptake were identified in the neck, thorax and elsewhere. Within the neck, the foci of 131I-increased uptake were graded qualitatively as probable or definite uptake in thyroid remnants and probable or definite uptake in the lymph nodes. Serum thyroglobulin level, histopathology and other imaging findings served as the reference standard. Results: Of the 67 patients, 57 (85%) had radioiodine avid disease and 10 (15%) demonstrated non-radioiodine avid disease. Overall, post-therapy 131I-SPECT/CT downstaged lymph node staging in 10 patients and upstaged it in 4 patients. This translated into a change of management for 9/57 (16%) patients with radioiodine avid disease. A change of management was observed in 5/10 patients with non-radioiodine avid disease confirmed in the post-131I-SPECT/CT study. Additionally, clinically significant findings such as incidental lung cancer, symptomatic pleural effusion and consolidation were also diagnosed in both groups of patients. Conclusion: In patients with thyroid cancer, 131I-SPECT/CT is a valuable addition to standard post-therapy planar imaging. SPECT/CT also improved diagnostic confidence and provided crucial clinical information leading to change of management for a significant number of these patients.

Keywords:
Thyroid cancer, Radioiodine, Single-photon emission computed tomography/computed tomography
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© 2015 European Thyroid Association Published by S. Karger AG, Basel
2015
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