Ali Sepahdari

Multiphasic multidetector parathyroid CT (“4D-CT”) is an increasingly popular tool for preoperative localization of abnormal parathyroid glands in patients with primary hyperparathyroidism. It is often used when other techniques fail, and is increasingly also being used as a first-line localization strategy.

The existing literature on 4D-CT has documented and validated its advantages over scintigraphy and ultrasound, but we know that 4D-CT remains imperfect. In particular, the approximately 10–30% of primary hyperparathyroidism cases that are caused by multiglandular disease (MGD) represent a large share of discordances between 4D-CT and surgical exploration—in our experience and in the literature.

We had two goals for this study. First, we wanted to get a better sense of the true performance of 4D-CT, specifically with regard to MGD, as this topic had not been fully explored in prior studies. Second, we wanted to make better use of the available imaging and clinical information to make evidence-based diagnoses of either MGD or single-gland disease in the future. We thought this would be best accomplished with a multi-institutional study, to mitigate biases related to different patient populations and potentially differing sensitivities between readers.

We found that a substantial number of cases could be confidently diagnosed as either MGD or single-gland adenoma using the MGD Score, and that performance was similar across different radiologists and different patient populations. The method we described can be easily applied by anyone reading 4D-CT in a clinical setting, without the need for sophisticated analysis tools.

We have since incorporated these research findings into our clinical practice. Our dictated reports reflect our overall confidence in a diagnosis of either single adenoma or MGD based on the MGD Score criteria. These data inform surgical decision-making, particularly with respect to whether a unilateral or bilateral neck exploration is planned. Although many surgeons currently perform all parathyroidectomies under general anesthesia in a hospital facility with available intraoperative parathyroid hormone monitoring, the MGD Score data could be used to identify appropriate candidates for parathyroidectomy to be done under local anesthesia, and/or in a facility without available intraoperative hormone monitoring. A patient with a well-localized single gland and a low MGD Score is the ideal candidate for such a procedure.

Our next step was to perform a prospective validation of the MGD Score. Because the MGD Score was retrospectively derived, it is subject to statistical bias. We successfully applied the MGD Score to a prospective patient population at UCLA, achieving similar performance to the retrospective multi-institutional study. These results will be published in AJNR in the coming months. We hope to continue refining our predictive model and to conduct further outcomes-based research on this topic.

Read this article at AJNR.org …