Value of Dual-Time-Point [18F]Fluorocholine PET/CT for Challenging Preoperative Parathyroid Imaging.

[18F]fluorocholine ([18F]FCH) PET/CT localizes hyperfunctioning parathyroid glands in patients with primary hyperparathyroidism, but the optimal imaging time remains uncertain. We evaluated the added value of a 60-min acquisition after a 10-min acquisition. Methods: Patients with primary hyperparathyroidism who underwent parathyroid surgery after [18F]FCH PET/CT were included in the study. PET/CT was performed 10 min (early) and 60 min (delayed) after [18F]FCH injection. Gland location, SUVmax, SUVpeak, and parathyroid-to-thyroid ratio were reported. Results: Among 162 glands surgically removed in 119 patients, the median SUVmax (5.5 vs. 4.9, P < 0.01) and parathyroid-to-thyroid ratio (1.6 vs. 1.4; P < 0.01) were higher at 60 min versus 10 min, whereas the SUVpeak did not significantly differ between acquisition times. Delayed [18F]FCH PET/CT produced visually superior images for 36 of 113 resected PET-positive glands and changed the clinical interpretation for 23 (19.3%) of 119 cases, revealing an adenoma after a negative early scan in 8 patients. Conclusion: Although early imaging can provide more information, selective delayed imaging offers improved contrast and confidence in negative or equivocal cases.