Abstract:

Objective To investigate the incremental value of ¹³¹I-SPECT/CT fusion imaging over ¹³¹I whole-body scintigraphy (WBS) in the management of patients with differentiated thyroid carcinoma (DTC). Methods Eighty-two patients with DTC underwent both WBS and SPECT/CT imaging after ¹³¹I therapy. The capacity of location and qualitative analysis of radioiodine avid lesions of SPECT/CT imaging was compared with that of WBS. The capacity of SPECT/CT imaging in detecting non-radioiodine avid lesions was analysed. The impact of SPECT/CT imaging on diagnosis of metastases, clinical staging and therapeutic strategy was evaluated. Results Two hundred and three radioiodine avid lesions were detected by WBS. Eighty-nine of them (43.84%) were located by WBS, which was verified by SPECT/CT imaging. Thyroid remnant and bone were the regions with highest accuracy, with accuracy rates of 74.24% (49/66) and 62.86% (22/35) respectively. WBS determined 52 benign radioiodine avid lesions, 36 malignant ones and 115 uncertain ones, and SPECT/CT imaging determined 94, 79 and 30 respectively. The percent of uncertain radioiodine avid lesions determined by SPECT/CT imaging was significantly lower than that determined by WBS (14.78% vs 56.65%, χ2=77.51, P<0.01). Besides, 6 non-radioiodine avid metastatic lesions were detected by SPECT/CT imaging. Among all the 82 patients, 14 (17.07%) were changed about the diagnosis of metastasis, 5 (6.1%) were changed about the clinical stage, and 23 (28.05%) were changed about the therapeutic strategy through SPECT/CT imaging. Conclusion SPECT/CT fusion imaging has incremental value in differentiating radioiodine avid lesions, detecting non-radioiodine avid lesions, improving accuracy of diagnosis, and adjusting therapeutic strategy of DTC.

Key words: differentiated thyroid carcinoma, iodine radioisotopes, tomography, emission computed