Molecular Imaging Versus Adrenal Vein Sampling for the Detection of Surgically Curable Primary Aldosteronism

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. 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). Prospective within-patient comparison of diagnostic interventions. (ClinicalTrials.gov: NCT02945904). Three referral centers. 174 patients with PA desiring surgery if a unilateral source of PA was diagnosed. [11C]MTO and AVS in 169 patients, plus [18F]CETO in the final 31. 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. 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]). The accuracy of [11C]MTO could be assessed only in the surgical group. Molecular imaging is an accurate, noninvasive alternative to AVS. National Institute for Health and Care Research.