Diagnostic performance of 3T MRI preoperative localization of parathyroid adenomas in primary hyperparathyroidism.

OBJECTIVE: Preoperative localization is essential for the surgical management of primary hyperparathyroidism (PHPT). Ultrasound and 99mTc-sestamibi SPECT/CT are first-line imaging modalities, while MRI's role is less defined. This study aimed to evaluate MRI for parathyroid adenoma localization in PHPT and compare it with that of ultrasound and SPECT/CT. METHODS: In this prospective single-center study, 103 adults with biochemically confirmed PHPT underwent ultrasound, multiparametric 3T MRI, and SPECT/CT before surgery. MRI examinations were independently evaluated independently evaluated by two blinded radiologists. Surgical and histopathological findings served as the reference standard. RESULTS: Ninety-three patients (90%) had single-gland disease (SGD), and 10 (10%) multiglandular disease (MGD). MRI demonstrated high sensitivity for adenomas in SGD but significantly lower sensitivity in MGD: Reader 1, 0.824 vs 0.476 (p = 0.002) and Reader 2, 0.890 vs 0.524 (p < 0.001). Ultrasound and SPECT/CT showed similar patterns. Specificity did not differ significantly between SGD and MGD. Inter-reader agreement was high for MRI and ultrasound (Krippendorff's α > 0.8) but decreased when including SPECT/CT. MRI-based size lesion size measurements showed good concordance between readers (ρC = 0.822) but showed low concordance with histology (ρC1 = 0.498; ρC2 = 0.373) due to systematic underestimation (15-18%). CONCLUSION: Multiparametric 3T MRI provides localization sensitivity to that of first-line imaging modalities in SGD, but differentiation between MGD and SGD remains challenging, with MRI showing no clear superiority over standard modalities.