Dual-Time-Point ¹⁸F-Fluorocholine PET/CT in Parathyroid Imaging

Abstract

18 F-fluorocholine ( 18 F-FCH) PET/CT is a promising and increasingly used scan technique in the preoperative imaging of parathyroid adenoma. Several acquisition methods have been evaluated in the literature, but the optimal image acquisition time point after administration of the tracer is still under debate. Methods: Patients who had hyperparathyroidism, underwent dual-time-point 18 F-FCH PET/ CT (image acquisition, 5 min; 60 min after injection), and had histologically proven pathologic parathyroid glands were retrospectively included in the study. Early and late images were compared both visually and quantitatively. Results: Sixty-four patients were included, and a total of 71 parathyroid glands were surgically removed. Visually, there were no differences between early and late images of hyperfunctioning parathyroid glands in 44 patients (69%); in 13 patients (20%), visualization on early images was better; in 6 patients (9%), visualization of hyperfunctioning glands was best on late images; and in 1 patient (2%), the lesion was exclusively visualized on late images. For the total cohort, there was a significant decrease in 18 F-FCH uptake in the glands on late versus early time points (P 5 0.001), but there was a significant increase in the ratio of parathyroid uptake to thyroid uptake (P 5 0.037). The group of patients with better visualization on early images showed a decrease over time in both parathyroid uptake and the ratio of parathyroid uptake to thyroid uptake, significant in comparison to those in both the group with better visualization at later time points and the group in which visualization was similar at both time points (P values of 0.000-0.018). There were no significant differences in 18 F-FCH uptake and the ratio of parathyroid uptake to thyroid uptake between the latter 2 groups (P values of 0.200-0.709). Conclusion: In most patients (89%), hyperfunctioning parathyroid glands were adequately visualized on early imaging; however, in a subset of patients (11%), such glands were best visualized at later time points. Therefore, we recommend the acquisition of dual-time-point images in parathyroid imaging with 18 F-FCH PET/CT or the creation of an opportunity to acquire additional late images after review of early images when findings are inconclusive.

Preoperative Localization of Adenomas in Primary Hyperparathyroidism: The Value of 11C-Choline PET/CT in Patients with Negative or Discordant Findings on Ultrasonography and 99mTc-Sestamibi SPECT/CT

“…Another limitation is that, because of the short half-life of 11 C, late imaging was not feasible in our study. A combination of early and delayed imaging was recently shown to detect additional PTAs using 18 F-fluorocholine PET/CT in a large collective of 64 patients (28). A direct comparison cannot be made because of differences in the patient collective and study setup; however, even when the inconclusive cases are included, the ratio of parathyroid to normal thyroid tissue in our study appears to be at least as high as the ratio in the above-mentioned study (28).…”

18F-Fluorocholine PET and Multiphase CT Integrated in Dual Modality PET/4D-CT for Preoperative Evaluation of Primary Hyperparathyroidism

“…Four pathologic parathyroids (two patients) were not detected by the three imaging modalities probably due to their small size and weight (less than 10 mm and 0.1 g), an uncommon histological characteristic (one case of oncocytic micro-adenoma), and patient biological profiles (slight PTH increase (83 pg/mL) and subnormal calcemia (2.60 mmol/L) in one case, and moderate PTH increase (102 pg/mL) and vitamin D insufficiency (21 ng/mL) in the other one). Interestingly, some recent evidence points out the potential of a PET dual-time-point acquisition protocol to reduce false negative results in cases of negative/inconclusive standard PET study [ 27 ]. As previously reported [ 28 , 29 ], we found a positive and significant correlation between blood PTH level, parathyroid gland weight, and both SUVmax and MTV.…”

Diagnostic Value of Choline PET in the Preoperative Localization of Hyperfunctioning Parathyroid Gland(s): A Comprehensive Overview

“…When comparing early and delayed static acquisitions, several authors observed a better lesion-to-background and lesion-to-thyroid contrast on late images but all lesions were visible at both phases [16,17,21,31].…”

“…In the setting of benign lesions, dual time scanning can help with a differential diagnosis; in the late phase, choline uptake decreases both in the thyroid gland parenchyma and inflammatory lymph nodes whereas it increases in parathyroid adenomas [25,26,31]. Similarly, Prabhu et al reported that early dynamic imaging could also be helpful in differentiating between parathyroid adenomas and cervical reactive lymph nodes that might be confused with small adenomas/hyperplasic glands.…”