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

• Published in: Annales d'endocrinologie Vol. 82; no. 2; p. 83
• Main Authors: Benderradji, Hamza, Beron, Amandine, Wémeau, Jean-Louis, Carnaille, Bruno, Delcroix, Laurent, Do Cao, Christine, Baillet, Clio, Huglo, Damien, Lion, Georges, Boury, Samuel, Cussac, Jean-Félix, Caiazzo, Robert, Pattou, François, Leteurtre, Emmanuelle, Vantyghem, Marie-Christine, Ladsous, Miriam
• Format: Journal Article
• Language: English
• Published: France 01.04.2021
• Subjects: Adult; Aged; Biopsy, Fine-Needle; Diagnosis, Differential; Female; Humans; Iodine Radioisotopes; Male; Middle Aged; Radionuclide Imaging - methods; Reproducibility of Results; Retrospective Studies; Sensitivity and Specificity; Technetium Tc 99m Sestamibi; Thyroid Neoplasms - diagnostic imaging; Thyroid Neoplasms - pathology; Thyroid Neoplasms - surgery; Thyroid Nodule - diagnostic imaging; Thyroid Nodule - pathology; Thyroid Nodule - surgery; Ultrasonography; Nodule thyroïdien; Malignité; Scintigraphie au (99m)Tc-MIBI; Indeterminate or non-diagnostic cytology; Surgery; Chirurgie; Thyroid nodule; Malignancy; Cytologies indéterminées ou non diagnostiques; (99m)Tc-MIBI scintigraphy
• ISSN: 2213-3941

The aim of this study was to evaluate the role of dual isotope Iodine/ Tc-MIBI thyroid scintigraphy (IMS) in discriminating between malignant and benign lesions in indeterminate nodules using quantitative analysis methods. Thirty-five consecutive patients with thyroid nodules of indeterminate or non-diagnostic cytology and cold on Iodine 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. 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%. Despite some study limitations, quantitative analysis of Tc-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.