Localization in primary hyperparathyroidism

Primary hyperparathyroidism is the main cause of hypercalcemia, resulting predominantly from parathyroid adenomas followed by hyperplasia. Diagnosis relies on clinical and biochemical parameters. Accurate pre-operative localization is mandatory for better surgical outcome. Various non-invasive imaging modalities includes cervical ultrasound, radionuclide scintigraphy with 99mTc-Methoxyisobutyl isonitrile combined with SPECT/CT, 4DCT, MRI and 18F-Choline PET/CT. Functional imaging has shown higher accuracy in localization especially in ectopic parathyroid adenomas and persistent or recurrent hyperparathyroidism. Combined ultrasound and 99mTc-MIBI has shown high sensitivity and specificity than individual imaging modality. 18F-Choline PET/CT has better diagnostic performance in identifying parathyroid hyperplasia and multiple adenomas. In patients with equivocal findings and concurrent thyroid nodular diseases, 18F-Choline PET/MRI and 4DCT helps in better characterization of lesion. Intraoperative probe guided surgery facilitates targeted and minimally invasive surgery resulting in better surgical outcome. More specific radiopharmaceuticals for parathyroid imaging need to be developed to reduce false positive results.