Abstract
This study investigated the usefulness of iodine-131 (I-131) single photon emission computed tomography-computed tomography (SPECT-CT) in conjunction with whole-body scan (WBS) planar imaging for the management of a patient presenting with differentiated thyroid carcinoma (DTC). A total of 100 patients with DTC post-total thyroidectomy were included in the study The foci of I-131 uptake were classified as neck site and outside the neck site by WBS planar and SPECT-CT imaging. SPECT-CT incrementally identified 141 neck sites and 217 distant neck foci compared to 139 at the neck site and 197 at the outside neck site identified by planar imaging. For the neck site, SPECT-CT downstaged 27 foci of 32 for indeterminate thyroid remnants at the neck site. Regarding sites distant to the neck, the SPECT-CT analysis led to the correct downstaging of two false-positive foci of suspicious uptake within the lung and bone, which were noted as metastases on planar images. SPECT-CT correctly upstaged one focus of iodine activity observed in the left arm as contamination on planar images, subsequently corrected as a metastatic bone lesion. The use of I-131 SPECT-CT scans increased the incremental diagnostic data compared with I-131 WBS planar scan imaging alone, which could change patient management.