MR Pulse Sequences for Parathyroid Adenoma Imaging Using [¹⁸F]fluorocholine PET/MR in Primary Hyperparathyroidism

Currently, no standardized anatomic magnetic resonance (MR) imaging protocol exists for detecting parathyroid adenomas. We analyzed various MR pulse sequences to evaluate their performance in visualizing histopathologically confirmed parathyroid adenomas in patients with primary hyperparathyroidism (pHPT) undergoing [¹⁸F]fluorocholine positron emission tomography (PET)/MR.

This retrospective study included 128 adenomas in 110 patients with biochemically confirmed pHPT who underwent [¹⁸F]fluorocholine PET/MR at our institution between December 2020 and October 2023. Two radiologists independently characterized the lesions (as upper pole, lower pole, or ectopic adenomas). Surgical reports and histopathology served as reference standard. Lesion conspicuity, delineation, and size were compared on axial T1-weighted fast spin echo sequence (T1w FSE) and axial T2-weighted iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL) sequence with water image reconstruction (T2w FSE flex water). Interreader agreement was determined using Cohen's kappa; differences were analyzed using Wilcoxon signed-rank test.

Parathyroid adenomas had significantly higher conspicuity, superior delineation, and were larger (p < 0.001) on T2w FSE flex water images compared to T1w FSE images. While these differences were maintained in the subgroup analysis for upper and lower pole adenomas, ectopic adenomas were of similar size on both MR pulse sequences (p = 0.646).

T2w FSE flex water offers significantly better visualization of parathyroid adenomas compared to T1w FSE, especially in orthotopic lesions. These results support the targeted use of such a limited MR protocol as part of PET/MR in the preoperative assessment of patients with pHPT.