The Role of 131I SPECT-CT as a Diagnostic Tool in Management of Patients with Differentiated Thyroid Cancer

purpose of the study was to estimate the value of using of 131I single photon emission tomography – computed tomography (SPECT/CT) in differentiated thyroid carcinoma (DTC) for diagnoses and follow up. Methods: Eighty-seven planar whole body scan (WBS) and SPECT/CT neck and chest were obtained for 77 pathologically proved DTC patients (17 males and 60 females; age range, 14 – 79 years). Fifty-two scans were 131I diagnostic (Dx) follow up studies, and 35 scans were 131I post-therapy (Rx) studies. Results: Planar scans depicted 106 foci in 45 studies (61 in the neck and 45 in distant sites); SPECT/CT scans depicted 125 foci in 51 studies (72 in the neck and 53 indistant sites), and characterized 16 indeterminate foci on planar scans in 13 /45 positive planar studies (28.9%). Both Planar and SPECT-CT scans were concurrently positive in 45 studies (51.7%), concurrently negative in 36 studies (41.4%), and discordant in 6 studies (6.9%). The incremental diagnostic value of SPECT-CT over planar imaging was obtained for approximately 30 % of detected lesions. Conclusion: SPECT/CT had better diagnostic information compared with planar whole body imaging. It correctly modified the risk classification defined by planar imaging and allowed for avoidance of unnecessary radioiodine (RI) treatment.