Molecular Imaging Versus Adrenal Vein Sampling for the Detection of Surgically Curable Primary Aldosteronism : A Prospective Within-Patient Trial.

Abstract

BACKGROUND: Primary aldosteronism (PA) causes hypertension and is potentially surgically curable when it is caused by a unilateral aldosterone-producing adrenal adenoma (APA). Adrenal vein sampling (AVS) is required to guide surgery, but it is invasive, is technically difficult, and has limited availability. OBJECTIVE: To determine whether the accuracy of post-dexamethasone [11C]metomidate ([11C]MTO) positron emission tomography-computed tomography, a diagnostic test for APAs, is superior or noninferior to the accuracy of AVS in predicting outcomes from unilateral adrenalectomy, and whether [11C]MTO is interchangeable with its longer-half-life analogue, para-chloro-2-[18F]fluoroethyletomidate ([18F]CETO). DESIGN: Prospective within-patient comparison of diagnostic interventions. (ClinicalTrials.gov: NCT02945904). SETTING: Three referral centers. PARTICIPANTS: 174 patients with PA desiring surgery if a unilateral source of PA was diagnosed. INTERVENTION: [11C]MTO and AVS in 169 patients, plus [18F]CETO in the final 31. MEASUREMENTS: International consensus criteria for biochemical and clinical success at 6 and 24 months after surgery; κ statistic and Bland-Altman analyses comparing predictions of surgical outcomes by [11C]MTO and [18F]CETO. RESULTS: Eighty-nine of 169 (52.7%), 78 of 169 (46.2%), and 43 of 169 (25.4%) patients were predicted to have unilateral PA by [11C]MTO, AVS, or both, respectively. One hundred of 169 (59.1%) were assigned to adrenalectomy by the multidisciplinary team; primary outcome data were available for 156 of 169. Predictions were most accurate for complete or partial biochemical success ([11C]MTO, 71.3% [95% CI, 61.0% to 80.1%]; AVS, 62.8% [CI, 52.2% to 72.6%]) and least accurate for complete clinical success (home blood pressure <135/85 mm Hg off treatment). The 95% CIs around differences between accuracies crossed zero, excluding superiority for [11C]MTO, but not the prespecified lower bound of -17%, allowing [11C]MTO to be declared noninferior to AVS. [18F]CETO and [11C]MTO agreed in 29 of 31 patients (κ = 0.85 [CI, 0.68 to 1.00]). LIMITATION: The accuracy of [11C]MTO could be assessed only in the surgical group. CONCLUSION: Molecular imaging is an accurate, noninvasive alternative to AVS. PRIMARY FUNDING SOURCE: National Institute for Health and Care Research.