Introduction: Parathyroid 4D computer tomography (4D-CT) has emerged as a complimentary technique to ultrasound and sestamibi scintigraphy particularly in the localisation of ectopic or multigland disease.
Methods: A retrospective review of patients with primary hyperparathyroidism who underwent 4D-CT (performed at a single practice) over the period 2017-2018 because of suspected bilateral disease or discordant or negative imaging on prior localisation ultrasound (performed by a single operator) and sestamibi scintigraphy (majority performed with 99mTcpertechnetate subtraction). Adenoma localisation was confirmed at parathyroidectomy with subsequent cure.
Results: 28 patients were identified, 13 had undergone parathyroidectomy at time of abstract submission: average age was 70 years, 77% had mild (corrected calcium<2.75mmol/L) and 23% had moderate (corrected calcium 2.75-3.0mmol/L) primary hyperparathyroidism. Detection of findings ‘probably consistent’ with parathyroid adenoma at a specific location with ultrasound had sensitivity of 29% and positive predictive value (PPV) of 71%, scintigraphy had sensitivity of 53% and PPV of 82% and 4D-CT had sensitivity of 59% with PPV of 63%. Ten glands had concordant abnormality on two modalities with sensitivity 59% and PPV for adenoma at that site of 83%. Detection of findings ‘possibly consistent’ with parathyroid adenoma at a specific location with ultrasound had sensitivity of 41% with PPV of 70%, scintigraphy had sensitivity of 65% and PPV of 73% and 4D-CT had sensitivity of 71% with PPV of 55%. 13 glands had concordant abnormality on two modalities with sensitivity 76% and PPV for adenoma at that site of 76%. In this group all patients were cured with surgery.
Conclusions: Parathyroid 4D-CT is a complimentary imaging technique to localise parathyroid adenomas where other imaging is inconclusive. Concordant abnormalities in two of the three modalities improves localisation of parathyroid adenomas.