Quantitative dual isotope 123iodine/99mTc-MIBI scintigraphy: A new approach to rule out malignancy in thyroid nodules.

BACKGROUND: The aim of this study was to evaluate the role of dual isotope 123Iodine/99mTc-MIBI thyroid scintigraphy (IMS) in discriminating between malignant and benign lesions in indeterminate nodules using quantitative analysis methods. METHODS: Thirty-five consecutive patients with thyroid nodules of indeterminate or non-diagnostic cytology and cold on 123Iodine scintigraphy (10 Bethesda I, 24 Bethesda III-IV, 1 in which cytology was impossible) underwent IMS between 2017 and 2019 with uptake quantification at two time points ahead of thyroidectomy: early and late. Images were analyzed by two blinded physicians. RESULTS: Twelve nodules were malignant and 23 benign on histopathology. Mean uptake values were lower in benign than in malignant nodules at both time points: early, 8.7±4.1 versus 12.9±3.5 (P=0.005); and late, 5.3±2.7 versus 7.7±1.1 (P=0.008). Interobserver reproducibility was excellent. The intraclass correlation coefficient was 0.86 in benign and 0.92 in malignant lesions for early uptake result (ER) and 0.94 and 0.85 respectively for late uptake result (LR). The optimal LR cut-off  to exclude a diagnosis of malignancy was set at 5.9 . The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of this cut-off were, respectively, 100%, 65.2%, 60%, 100% and 77.1%. CONCLUSION: Despite some study limitations, quantitative analysis of 99mTc-MIBI thyroid scintigraphy had a good reproducibility, which could help to rule out malignancy in non-diagnostic or indeterminate thyroid nodules and thereby reducing the number of patients undergoing unnecessary surgery when LR is below 5.9.

Fine needle aspiration and intraparathyroid intact parathyroid hormone measurement for reoperative parathyroid surgery.

Some authors have praised the value of fine needle aspiration (FNA) with measurement of intraparathyroid intact parathyroid hormone (iPTH) for localization of the hypersecreting gland(s) in recurrent or persistent primary hyperparathyroidism (HPT). The aim of the present study was to determinate whether FNA for iPTH assay is an effective procedure to distinguish between normal and hypersecreting parathyroid glands. We performed a prospective study of 170 patients who underwent cervicotomy. They were divided into three groups: group A, 50 patients with thyroid diseases; group B, 100 patients with primary HPT; group C, 20 patients with secondary HPT. We performed intraoperative FNA for iPTH measurement from the thyroid, and from the normal and enlarged parathyroid glands, and we compared the different intraglandular iPTH assays. In group A, the intraparathyroid iPTH level was < 1000 pg/ml in 68% of the patients. In group B, in the pathological parathyroid gland iPTH was > 1000 in 88%; conversely, in the normal adjacent parathyroid glands it was < 1000 in 79%. In group C, intraparathyroid iPTH of enlarged glands was > 1000 in 80%. Intrathyroid iPTH was < 100 pg/ml in 96% for the three groups. We conclude that FNA for intraglandular iPTH measurement is an effective tool for distinguishing between normal and pathological parathyroid glands in the setting of primary HPT (p < 0.05), and between thyroid and parathyroid glands in groups A and B. But the procedure should be carried out in conjunction with the sestamibi scan and ultrasonography before surgical reintervention.