Analysis of Causes and Treatment Strategies for False Positive and False Negative of 99mTc-MIBI SPECT: Experience Sharing and Literature Review

For patients with suspected parathyroid gland tumors, 99mTc-MIBI SPECT dual-phase imaging of parathyroid glands was performed to analyze the results of false positives and false negatives, to explore treatment strategies and to summarize treatment experience. Method: We Analysed the false positive and false negative results of 99mTc-MIBI SPECT in 55 patients with suspected parathyroid glands treated by the author's medical team from January 2013 to April 2019. Combining preoperative examination results, intraoperative conditions and postoperative pathological data, we summarized the causes of false positive and false negative results, explored treatment strategies, and summarized treatment experience. Result:There were 11 cases of false positive and false negative result of 99mTc-MIBI SPECT. There were 4 cases of 99mTc-MIBI SPECT false positive in patients with non-primary parathyroidism, including 2 cases of nodular goite, 1 case of thyroid adenoma and 1 case of cervical ectopic thymoma; There were 5 cases of primary hyperpara-thyroidism patients with 99mTc-MIBI SPECT false negative, respectively, 1 case of parathyroid carcinoma, 1 case of parathyroid cyst, 1 case of smalle parathyroid adenoma, 1 case of cystic changes of parathyroid adenoma, 1 case of atypical parathyroid adenoma; There were 2 cases of primary hyperp-arathyroidism patient, 99mTc-MIBI SPECT results changed from negative to positive. One case 99mTc-MIBI SPECT result changed from negative to positive after 12 months interval, and her PTH increased from 310.5pg/ml to 887.4pg/ml. An ectopic parathyroid adenoma was found in her upper mediastinum and resected. The other case 99mTc-MIBI SPECT result changed from negative to positive after 42 months interval, PTH increased from 161pg/ml to 350pg/ml, and finally ectopic parathyroid glands were found in the posterior right sternosacral joint (zone VII) and surgically removed. Conclusion: Masses located on the dorsal side of the thyroid often need to be differentiated from parathyroid tumors. However, primary hyperparathyroidism first requires a qualitative diagnosis whether they was primary hyperparathy-roidism. If the qualitative diagnosis was negative, we need to consider whether it was a false positive caused by other diseases when the 99mTc-MIBI SPECT localization diagnosis was positive. If the qualitative diagnosis was positive, but the 99mTc-MIBI SPECT localization diagnosis was negative, and it was necessary to combine other examinations to assist in the localization of parathyroid tumors. 99mTc-MIBI SPECT can be changed from negative to positive in some patients with positive qualitative diagnosis and negative 99mTc-MIBI SPECT localization diagnosis.