Restaging of differentiated thyroid carcinoma with SPECT/CT after radioiodine therapy

Abstract

Purpose. The purpose of the study was to assess the diagnostic value of SPECT/CT data after radioiodine therapy in comparison with the data of soft tissue neck ultrasonography (US) and computed tomography (CT) in patients with differentiated thyroid carcinoma (DTC) and thus to investigate the role of SPECT/CT data in the restaging of DTC. Material and methods. We analyzed the results of 263 patients who were examined from November 2011 to April 2014, at the age of 10 to 78 years (190 female and 73 male). According to postoperative histological tests, 255 patients had papillary thyroid cancer and 38 patients had follicular thyroid cancer. Soft tissue neck US, CT of the chest without intravenous contrast and scintigraphy with 99mTc-pertechnetate in all patients were performed and then they were treated with radioiodine (dose, 3.0–5.5 GBq). Whole-body scintigraphy (WBS) and SPECT/CT were performed on the 3–5 day in all patients receiving radioiodine therapy. Results. After radioiodine therapy and SPECT/CT cancer stage diagnosed with US, CT, and scintigraphy was changed to N in 36.7% of patients, and cancer stage was changed to M in 11% of patients. The frequency of regio-nal cervical metastasis not detectable with US but suspected on WBS was 43.9%. In most cases, there were micrometastasis and lymph node metastases in the pre- and paratracheal areas, which were difficult to access by US. Conclusion. SPECT/CT after radioiodine therapy could improve the assessment of cancer stage and prognosis in patients with DTC.

Keywords

• differentiated thyroid carcinoma
• radioiodine therapy
• spect/ct