Noninvasive CT Scan Could Identify Primary Aldosteronism Patients Eligible for Adrenalectomy

Morris Brown, MD, FRCP

Data from a prospective, within-patient trial conducted in the United Kingdom suggests a new form of CT scan could improve the identification of primary aldosteronism in adult patients.

A comparison of the [11C]metomidate positron emission tomography computed tomography scan (MTO) against adrenal vein sampling, results of the study indicate use of the noninvasive scan was as accurate as adrenal vein sampling, with additional analysis indicating the scan can also provide insight into what patients may be able to discontinue hypertensive medications following surgical removal.

“These aldosterone-producing nodules are very small and easily overlooked on a regular CT scan. When they glow for a few minutes after our injection, they are revealed as the obvious cause of Hypertension, which can often then be cured,” said study investigator Morris Brown, MD, FRCP, professor of Endocrine Hypertension at Queen Mary University of London, in a statement. “Until now, 99% are never diagnosed because of the difficulty and unavailability of tests. Hopefully this is about to change.”

Although recognized as among the most common causes of hypertension, primary aldosteronism represents a perplexing issue for clinicians as well as patients. Despite this recognition, primary aldosteronism can often go undiagnosed for years and the invasive nature of adrenal vein sampling can steer patients away from exploring treatment. Citing the need for reliable, noninvasive diagnostic solutions, Brown and a team of collaborators from UK-based institutions designed the current study to evaluate use of MTO scanning for predicting biochemical remission of primary aldosteronism and the resolution of hypertension after surgery.

Named the MATCH trial, the prospective study enrolled 143 patients with primary aldosteronism from endocrine or hypertension clinics in the UK from December 2016-September 2020. The final study visit was completed on February 19, 2021 when the required number of patients had primary outcome measures following surgery. Due to interruptions occurring as a result of COVID-19 pandemic, investigators only included those who had either completed primary 6-month follow-up from surgery (n=78) or enrolled for and been allocated to medical treatment in the same time period as the 78 patients who received surgery.

The 128-patient cohort was 68% male, had a median age of 52 (IQR, 43-60) years, 58% were White, 30% were Black, and 11% were Asian. Of the 78 patients in the study who received surgery, 77 achieved at least 1 primary aldosteronism surgical outcome criterion for success.

Upon analysis, results indicated the accuracies of MTO at predicting biochemical and clinical success following adrenalectomy were 72.7% and 65.4%, respectively. In comparison, the accuracies of adrenal vein sampling were 63.6% and 61.5%, respectively. Investigators pointed out MTO was not significantly superior to adrenal vein sampling in further analysis, but the observed differences of 9.1% (95% CI, -6.5 to 24.1; P=.00055) and 3.8% (95% CI, -11.0 to 9.4; P=.0077) were within the study’s prespecified -17% margin for noninferiority. A total of 24 serious adverse events were observed during the trial. Investigators noted none of these events were considered related to either investigation and 22 of the 24 were fully resolved.

“This study was the result of years of hard work and collaboration between centres across the UK. Much of the ‘on the ground’ energy and drive came from the talented research fellows who, in addition to doing this innovative work, gave selflessly of their time and energy during the national pandemic emergency. The future of research in this area is in very safe hands,” added study investigator William Drake, MD, FRCP, professor of Clinical Endocrinology at Queen Mary University of London, in the aforementioned statement.

This study, “[11C]metomidate PET-CT versus adrenal vein sampling for diagnosing surgically curable primary aldosteronism: a prospective, within-patient trial,” was published in Nature Medicine.