Clinical value of 99Tcm-MIBI scintigraphy in patients with differentiated thyroid carcinoma after surgery and first 131I therapy

Abstract

Objective To evaluate the clinical value of 99Tcm-MIBI scintigraphy for diagnosis of residual thyroid tissue and metastasis in patients with DTC after their first 131I therapy. Methods From February 2010 to March 2014, 192 DTC patients (38 males, 154 females, average age (43.2±8.6) years) who received total or near-total thyroidectomy and were pathologically diagnosed as DTC (171 papillary and 21 follicular carcinomas) underwent 99Tcm-MIBI scan (average dosage: 740-925 MBq) 6 months after their first 131I therapy. 131I scans was performed 4 d after oral administration of 131I of therapeutic dose (average dosage: 5 550-8 140 MBq). Pre- and post-therapeutic images and the serum Tg level (detected before the imagings) were compared and analyzed. Any abnormal uptake of agent found inside or outside the thyroid was regarded as positive result. Patient-based and lesion-based data analysis were performed by χ2 test and two-sample t test. Results A total of 191 patients were finally included, of which 65 positive cases were found. The sensitivity of 99Tcm-MIBI imaging was significantly lower than that of 131I imaging(56.9% (37/65) vs 92.3%(60/65); χ2=14.7, P 0.05). The serum Tg level of positive groups (99Tcm-MIBI positive + 131I positive or 131I negative) were significantly higher than that of 99Tcm-MIBI negative + 131I negative group (t=-20.7 and -6.0, both P<0.01), and that of 99Tcm-MIBI positive + 131I negative group was higher than that of 131I positive + 99Tcm-MIBI negative group(t=-2.7, P<0.05). Conclusion 99Tcm-MIBI imaging could detect metastasis of DTC patient after first radioiodine therapy, but the value in detecting thyroid remnants is limited. Key words: Thyroid neoplasms; Radiotherapy; Iodine radioisotopes; Radionuclide imaging; MIBI