Differentiation of malignant and benign thyroid nodules using 10- and 60-minute Tc-99m MIBI scans

K. Zaplatnikov1, W. Wiedemann1, M. Plotkin2, F. Grünwald3; 1Nuclear Medicine Clinic Nürnberg, Nürnberg, GERMANY, 2Nuclear Medicine University Hospital Charite Berlin, Berlin, GERMANY, 3Frankfurt/Main University, Frankfurt/Main, GERMANY.



Aim: Tc-99m methoxysobutylisonitrate (MIBI) has been found to be taken up by various tumors, including thyroid cancer. We evaluated hypoechoic cold thyroid nodules on Tc-99m pertechnetate scintigraphy with high flow in ultrasound to evaluate the diagnostic value of MIBI examinations. The aim of this study was to find out if a thyroid cancer can be predicted on the basis of MIBI scintigraphy in patients with anticoagulation therapy. Methods: Single injection thyroid scintigraphy using Tc-99m MIBI 400-600 MBq was performed in 27 pts (7 m 20 w; 57±24). Scans were evaluated by visual examination (grading “high”, “moderate” uptake and “no uptake”) and by calculation of background radiouptake ratio (RUR) was evaluated. Results: 3 patients had a intense MIBI retention and underwent surgery: (histology revealed papillary carcinoma and folliculary folliculary carcinoma in one pat. folliculary adenoma, 4 pts. had a moderate uptake and underwent surgery too- 2 pat. have benign nodule in another two thyroiditis). Using the 60/10-minute thyroid lesion to background radiouptake ratio (RUR), malignant and benign thyroid nodules could be separated with a sensitivity, specificity, and negative predictive value of 84.4%, 82.45%, and 81.33%, respectively. The mean RUR for malignant thyroid lesions was 1.67+/-0.18, whereas for benign lesions, the ratio was significantly lower, 0.32+/-0.20 (P=0.0005). Conclusions: In patients, in whom a needle aspiration cytology is not possible (hampered by antigoagulation therapy), the Tc-99m MIBI scintigraphy appears to be a useful additional diagnostic tool in the preoperative assessment of suspected thyroid nodules