Comparison of Functional Imaging with 11c-Metomidate Positron Emission Tomography and Adrenal Venous Sampling for the Subtype Evaluation of Primary Aldosteronism

Presentation Number: SUN 507
Date of Presentation: April 2nd, 2017

Niina Matikainen*1, Minna Soinio2, Marko Seppänen2, Janne Seppänen3, Saara Metso3, Matti Välimäki1, William F Young Jr.4, Pirjo Nuutila2 and Pasi Nevalainen3
1Helsinki University Hospital, Finland, 2University of Turku, Finland, 3University of Tampere, Finland, 4Mayo Clinic, Rochester, MN

Abstract

Background: The Endocrine Society guidelines1 recommend bilateral adrenal vein sampling (AVS) in patients with primary aldosteronism (PA) who are eligible for surgery. However, AVS may have low technical success rate and lacks standardization of both the procedure and diagnostic cutoffs used. A recent RCT demonstrated that treatment based on CT or AVS did not show any apparent significant differences in intensity of antihypertensive medication or clinical benefits after 1 year of follow-up2. Functional imaging with 11C-labeled metomidate that traces 11β-hydoxylase activity in the adrenal cortex could offer a noninvasive alternative to AVS3.

Methods: We studied 54 patients with confirmed PA1. The test performance characteristics of AVS, CT, and 11C-metomidate PET to lateralize adrenal aldosterone hypersecretion were analyzed in 34 patients (mean age = 54 y; mean BMI = 30 kg/m2) who underwent curative adrenalectomy. Surgery was based on an AVS aldosterone lateralization gradient ≥4 or, in case of unsuccessful AVS, on the findings on 11C-metomidate PET and CT as judged by a clinician.

Results: Biochemical cure was documented at approximately 2 months after adrenalectomy. The mean aldosterone concentration decreased from 870 ± 589 pmol/l preoperatively to 124 ± 105 pmol/l postoperatively (P<.001). The ARR normalized in all surgically treated patients. Following surgery potassium supplements and/or spironolactone were discontinued and plasma K increased from 3.4 ± 0.40 mmol/l to 4.05 ± 0.47 mmol/l (P<.001). The mean BP decreased from 155/94 mmHg to 133/80 mmHg (P<.001) and the number of antihypertensive agents used decreased from 2.5 to 1.4 formulations. AVS was unsuccessful in 4 patients and failed to lateralize in one operated patient (sensitivity = 96.7 %) with overall AVS success rate of 85.3 %. CT evaluated in the clinical units correctly demonstrated lateralization in 22/34 subjects with sensitivity of 64.7 %. 11C-metomidate PET was performed in 33 patients and lateralized correctly in 26/33 (79%), did not show lateralization in 4/33, and lateralized to contralateral side in 2/33 (false negative rate = 21%).

Conclusions: In 34 patients with PA who were cured with unilateral adrenalectomy, AVS was highly accurate when it could be performed successfully. 11C-metomidate PET demonstrated higher sensitivity than CT and may be of assistance in visualization of aldosterone-producing adenomas.

 

Nothing to Disclose: NM, MS, MS, JS, SM, MV, WFY Jr., PN, PN