To investigate the value of presurgical ¹⁸ F-FCH PET/CT in detecting additional hyperfunctioning parathyroids despite a positive ^99m Tc-sestamibi parathyroid scintigraphy in patients with primary hyperparathyroidism (pHPT).
This is a retrospective study involving patients with pHPT, positive parathyroid scintigraphy performed before ¹⁸ F-FCH PET/CT, and parathyroid surgery achieved after PET/CT. Imaging procedures were performed according to the EANM practice guidelines. Images were qualitatively interpreted as positive or negative. The number of pathological findings, their topography, and ectopic location were recorded. Histopathology, Miami criterion, and biological follow-up were considered to ensure effective parathyroidectomy confirming the complete excision of all hyperfunctioning glands. The impact of ¹⁸ F-FCH PET/CT on therapeutic strategy was recorded.
64/632 scanned pHPT patients (10%) were included in the analysis. According to a per lesion-based analysis, sensitivity, specificity, positive predictive value, and negative predictive value of ^99m Tc-sestamibi scintigraphy were 82, 95, 87, and 93%, respectively. The same values for ¹⁸ F-FCH PET/CT were 93, 99, 99, and 97%, respectively. ¹⁸ F-FCH PET/CT showed a significantly higher global accuracy than ^99m Tc-sestamibi scintigraphy: 98% (CI: 95-99) vs. 91% (CI: 87-94%). Youden Index was 0.79 and 0.92 for ^99m Tc-sestamibi scintigraphy and ¹⁸ F-FCH PET/CT, respectively. Scintigraphy and PET/CT were discordant in 13/64 (20%) patients (49 glands). ¹⁸ F-FCH PET/CT identified nine pathologic parathyroids not detected by ^99m Tc-sestamibi scintigraphy in 8 patients (12.5%). Moreover, ¹⁸ F-FCH PET/CT allowed the reconsideration of false-positive scintigraphic diagnosis (scinti+/PET-) for 8 parathyroids in 7 patients (11%). The ¹⁸ F-FCH PET/CT influenced the surgical strategy in 7 cases (11% of the study population).
In a preoperative setting, ¹⁸ F-FCH PET/CT seems more accurate and useful than ^99m Tc-sestamibi scan in pHPT patients with positive scintigraphic results. Positive parathyroid scintigraphy could be not satisfactory before neck surgery particularly in patients with multiglandular disease, suggesting a need to evolve the practice and define new preoperative imaging algorithms including ¹⁸ F-FCH PET/CT at the fore-front in pHPT patients.