Diagnostic Performance of Cervical Ultrasound, <sup>99m</sup>Tc-Sestamibi Scintigraphy, and Contrast-Enhanced <sup>18</sup>F-Fluorocholine PET in Primary Hyperparathyroidism
Vincent Boudousq, Nicolas Guignard, O. Gilly, B. Chambert, Adel Mamou, Olivier Moranne, Mathilde Zemmour, H. Sharara, B. Lallemant
Abstract
<b>Purpose:</b> Preoperative localization of pathological parathyroids is crucial for a minimally invasive treatment of primary hyperparathyroidism (PHPT). This study compares contrast-enhanced <sup>18</sup>F-fluorocholine positron emission tomography (FCH-PET/CT), cervical ultrasound (CU) and conventional scintigraphic imaging modalities (MIBI scintigraphy), combined and individually for preoperative localization of hyper-functional parathyroids in PHPT. The gold standard is histological examination. <b>Methods:</b> Data from consecutive patients with a clinical suspicion of PHPT were retrospectively collected. All three imaging modalities were systematically performed. MIBI scintigraphy, consisted of <sup>99m</sup>Tc-sestamibi/<sup>123</sup>I-sodium iodide SPECT/CT, <sup>99m</sup>Tc-sestamibi/<sup>123</sup>I-sodium iodide planar subtraction imaging and <sup>99m</sup>Tc-sestamibi planar dual-phase imaging. The ability of FCH-PET/CT, CU and MIBI scintigraphy to identify a hyper-functional parathyroid and specify the side or identify an ectopic location was noted. Patients underwent surgical exploration if at least one exam was positive. CU + MIBI scintigraphy combined was considered as a positive test if CU and MIBI scintigraphy separately showed a hyper-functional parathyroid gland on the same side, or the same ectopic location, and negative in other cases. The composite judgment criterion for pathological parathyroid combined histological analysis and normalization of PTH and calcium levels. <b>Results:</b> 149 pathological parathyroids were found in 143 of the 144 included patients. FCH-PET/CT diagnosed 148/149 pathological parathyroids. Only four false positives and one false negative were found. The FCH-PET/CT sensitivity of 99.3% was superior to that of CU at 75.2% (<i>P</i> < 0.0001), MIBI scintigraphy at 65.1% (<i>P</i> < 0.0001) and CU + MIBI scintigraphy combined at 89.9%, (<i>P</i> = 0.0009). 5/5 ectopic locations were diagnosed by FCH-PET/CT, 2/5 by MIBI and 0/5 by CU. Accuracy was better for FCH-PET/CT at 98% than CU at 84% (<i>P</i> < 0.0001), MIBI scintigraphy at 81% (<i>P</i> < 0.0001) or CU + MIBI scintigraphy at 91% (<i>P</i> < 0.0001). Among the 72 (50%) patients who had a negative CU + MIBI scintigraphy combined test, FCH-PET/CT correctly identified hyper-functional thyroids in 70 (97.2%) patients. Average FCH-PET/CT hyperfunctional parathyroid uptake was higher than the adjacent thyroid (SULmax 6.45 vs 2.15) (<i>P</i> < 0.0001). <b>Conclusion:</b> Accuracy of FCH-PET/CT is higher than CU and MIBI scintigraphy for localization of hyper-functional parathyroids, justifying the systematic use of FCH-PET/CT as the first-line method for PHPT diagnosis.