Discriminative Capacity of CT Volumetry to Identify Autonomous Cortisol Secretion in Incidental Adrenal Adenomas

Abstract

Context Incidentally discovered adrenal adenomas are common. Assessment for possible autonomous cortisol excess (ACS) is warranted for all adrenal adenomas given the association with increased cardiometabolic disease. Objective To evaluate the discriminatory capacity of three-dimensional volumetry on computed tomography (CT) to identify ACS. Design, Setting, Patients Two radiologists, blinded to hormonal levels, prospectively analyzed CT images on 149 adult patients with unilateral, incidentally-discovered, adrenal adenomas. Main Outcome Measures Diameter and volumetry of the adenoma, volumetry of the contralateral adrenal gland, and the adenoma volume-to-contralateral gland volume (AV/CV) ratio were measured. ACS was defined as cortisol≥1.8 mcg/dL after 1mg dexamethasone suppression test (DST) and a morning ACTH ≤15 pg/mL. Results We observed that ACS was diagnosed in 35 (23.4%) patients. Cortisol post-DST was positively correlated with adenoma diameter and volume, and inversely correlated with contralateral adrenal gland volume. Cortisol post-DST was positively correlated with the AV/CV ratio (r=0.46, p<0.001) and ACTH was inversely correlated (r=-0.28, p<0.001). The AV/CV ratio displayed the highest Odds Ratio (1.40 CI 95% 1.18-1.65) and area under curve (0.91 CI 95% 0.86-0.96) for predicting ACS. An AV/CV ratio ≥1 (48% of the cohort) had a sensitivity of 97% and a specificity of 70% to identify ACS. Conclusions CT volumetry of adrenal adenomas and contralateral adrenal glands has a high discriminatory capacity to identify ACS. The combination of this simple and low-cost radiological phenotyping can supplement biochemical testing to substantially improve the identification of ACS.

Association between contralateral adrenal and hypothalamus-pituitary-adrenal axis in benign adrenocortical tumors

“…found a negative linear correlation between limb width of the contralateral adrenal gland and cortisol levels after DST in patients with unilateral adrenal adenomas ( 18 ). Another study showed the significance of the volume of adrenal adenomas and contralateral adrenal glands associated with cortisol secretion ( 19 ). In our study, we found that patients with MACS had thinner contralateral adrenal compared with NFAT.…”

The Spectrum from Overt Primary Aldosteronism to Mild Dysregulated Aldosterone Production in Incidentally Discovered Adrenocortical Adenomas

“…The adrenal lesion was confirmed as an adenoma using attenuation criteria <10 Hounsfield units (HU) in unenhanced images or strict washout criteria when delayed contrast images were available (relative washout >40% and/or absolute washout >60%). 1,15 When magnetic resonance imaging (MRI) was available, signal drop on out-of-phase images was considered diagnostic of an adenoma. When these methods were not available or diagnosis was unclear, confirmatory CT using a standard adrenal protocol was performed (noncontrast imaging, 70-second post-contrast venous phase imaging, and 10- to 15-minute delayed post-contrast phase), using known density and washout criteria for adenoma diagnosis.…”

“…The Program for Adrenal Disorders at our institution has implemented a systematic hormonal assessment for all adrenal incidentalomas, as previously described. 14,15 On the first day, blood samples were obtained between 08:00 and 09:00, after an 8-hour overnight fast, for measurement of seated plasma aldosterone concentration (PAC), plasma renin activity (PRA) and/or direct renin concentration (DRC), ACTH, serum creatinine, sodium and potassium. All patients submitted a 24h urine collection to measure urinary aldosterone, cortisol, cortisone and sodium.…”

“…All patients were advised to consume an unrestricted sodium diet 48h before screening to avoid false negative results as previously described. 2,15,16…”

“…All patients were advised to consume an unrestricted sodium diet 48h before screening to avoid false negative results as previously described. 2,15,16 All blood samples were analyzed in the Clinical Laboratory of our institution, which meets international standards, such as the quality control program of the College of American Pathologist's Laboratory Accreditation Program. Mild autonomous cortisol secretion (MACS) was defined as post-dexamethasone cortisol >1.8 ug/dL with a morning ACTH <15 pg/mL.…”