Diagnostic Performance of Cervical Ultrasound, ^99mTc-Sestamibi Scintigraphy, and Contrast-Enhanced ¹⁸F-Fluorocholine PET in Primary Hyperparathyroidism.

Abstract

Preoperative localization of pathologic parathyroids is crucial for minimally invasive treatment of primary hyperparathyroidism (PHPT). This study compared contrast-enhanced ¹⁸F-fluorocholine PET/CT, cervical ultrasonography (CU), and conventional scintigraphic imaging modalities (MIBI scintigraphy, consisting of ^99mTc-sestamibi/¹²³I-sodium iodide SPECT/CT, ^99mTc-sestamibi/¹²³I-sodium iodide planar subtraction imaging, and ^99mTc-sestamibi planar dual-phase imaging), combined and individually, for preoperative localization of hyperfunctional parathyroids in PHPT. The gold standard was histologic examination. <b>Methods:</b> Data from consecutive patients with clinically suspected PHPT were retrospectively collected. All 3 imaging modalities were systematically performed. The ability of ¹⁸F-fluorocholine PET/CT, CU, and MIBI scintigraphy to identify a hyperfunctional parathyroid and specify the side or identify an ectopic location was noted. Patients underwent surgical exploration if at least 1 examination was positive. The findings of CU + MIBI scintigraphy combined were considered positive if CU and MIBI scintigraphy separately showed a hyperfunctional parathyroid gland on the same side or in the same ectopic location; any findings other than these were considered negative. The composite judgment criterion for pathologic parathyroid was a combination of histologic analysis and normalization of parathyroid hormone and calcium levels. <b>Results:</b> In total, 149 pathologic parathyroids were found in 143 of the 144 included patients. ¹⁸F-fluorocholine PET/CT diagnosed 148 of 149 pathologic parathyroids. Only 4 false-positives and 1 false-negative were found. The ¹⁸F-fluorocholine 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, at 89.9%, (<i>P</i> = 0.0009). Five of the 5 ectopic locations were diagnosed by ¹⁸F-fluorocholine PET/CT, 2 of the 5 by MIBI scintigraphy, and none by CU. Accuracy was better for ¹⁸F-fluorocholine PET/CT, at 98%, than for 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 result, ¹⁸F-fluorocholine PET/CT correctly identified hyperfunctional thyroids in 70 (97.2%). Average uptake in the ¹⁸F-fluorocholine PET/CT hyperfunctional parathyroid was higher than that in the adjacent thyroid (SUV_max adjusted for lean body mass, 6.45 vs. 2.15) (<i>P</i> < 0.0001). <b>Conclusion:</b> The accuracy of ¹⁸F-fluorocholine PET/CT is higher than that of CU and MIBI scintigraphy for localization of hyperfunctional parathyroids, justifying the systematic use of ¹⁸F-fluorocholine PET/CT as the first-line method for PHPT diagnosis.