ABSTRACT
Objective To evaluate the clinical value of 131 Ⅰ SPECT/CT in the differentiation of indeterminate 131Ⅰ uptake on planer whole body scan (WBS) for patients with DTC after 131Ⅰ treatment. Methods Fifty-six DTC patients ( male: 19, female: 37, mean age: 45 ± 15 years, ranging from 20 to 85 years) underwent 131Ⅰ treatment. 131Ⅰ WBS was performed five days after 131 Ⅰ treatment, followed by regional 131Ⅰ SPECT/CT for the indeterminate foci with abnormal uptake on 131Ⅰ WBS. The diagnostic difference of the two imaging modalities was compared by x2 test. Results There were 288 foci with abnormal uptake on 131 Ⅰ WBS, including 108 indeterminate foci (37.5%). Subsequent 131Ⅰ SPECT/CT identified 27 foci as DTC metastases (25.0%) and 71 foci as non-metastases such as benign lesions at nose, oral cavity, salivary gland, maxillary cyst, thyroid remnant, thymus, gallbladder, gastrointestinal tract, and uterus, or non-specific uptake of body contaminations (65.7%). However, the remaining 10 foci (9.3%) remained indeterminate on 131 Ⅰ SPECT/CT imaging. The diagnostic accuracy of 131 Ⅰ SPECT/CT was significantly higher than that of 131Ⅰ WBS (x2 = 102.35, P＜0. 01). Conclusion 131Ⅰ SPECT/CT could significantly improve the diagnostic accuracy for the differentiation of indeterminate foci with abnormal uptake on 131Ⅰ WBS.