4D-CT facilitates focused parathyroidectomy in patients with primary hyperparathyroidism by maintaining a high negative-predictive value for uninvolved quadrants

Introduction: Improved preoperative localization facilitates minimally invasive parathyroidectomy for removal of parathyroid lesions therefore preventing an invasive bilateral neck exploration. As 4D-CT has emerged, its high specificity has helped with preoperative parathyroid lesion localization. A high negative predictive value (NPV) would serve to further confirm parathyroid lesion localization and limit unnecessary surgical exploration. This study's objective was to determine the NPV of preoperative 4D-CT and its facilitation of minimally invasive parathyroidectomy. Methods: A retrospective review was compiled for patients undergoing parathyroidectomy for primary hyperparathyroidism with a preoperative 4D-CT. Included patients were sorted into various groups for comparison: those with 4D-CT localizing to a single lesion, localizing to multiple lesions, and those with nonlocalizing findings; multiple hypercellular parathyroid gland versus single gland findings; extent of surgical exploration; lesion location; and patients with concomitant thyroid nodules. Negative predictive value was calculated and used to quantify the ability for 4D-CT to rule out biochemically significant parathyroid lesions. Results: In our review of 68 patients: sensitivity was 81.3%, specificity was 95.5%, positive predictive value was 87.1%, and negative predictive value was 93.3%. 86% had a single localizing 4D-CT, 7% had a non-localizing 4D-CT, and 7% had a multiple quadrant localizing 4D-CT. NPV for single and multi-localizing 4D-CT were 96.8% and 88.9%, respectively. Conclusion: Preoperative 4D-CT has a high negative predictive value (93.3%), suggesting in the majority of cases, a quadrant with no 4D-CT radiographic findings suspicious for parathyroid is unlikely to harbor biochemically significant parathyroid lesions.