Is a Reduction of Contralateral Adrenal Volume Assessed by CT Volumetry a Predictor of Autonomous Cortisol Secretion...

Adrenal incidentalomas are common lesions with potential functional activity such as autonomous cortisol secretion (ACS), which influences management. Current diagnosis relies on biochemical testing, notably the dexamethasone suppression test (DST). This study aimed to evaluate whether CT-derived volumetry of adrenal incidentalomas and contralateral adrenal glands-specifically the ratio of adenoma volume to contralateral volume (AV/CV) could serve as a reliable screening marker for ACS.

We retrospectively analysed all adult patients referred with unilateral adrenal adenomas between January 2022 and January 2023. Patients with bilateral lesions, metastatic disease, or interfering medications were excluded. All underwent standard hormonal assessment with 1 mg overnight DST and had volumetric analysis of adrenal glands on CT imaging performed independently by two radiologists, calculating AV, CV and their ratio. The correlation between AV/CV and post-DST cortisol levels was assessed using Pearson's coefficient, and ROC analysis evaluated the predictive accuracy.

Inter-observer variability was r = 0.997 for AV and r = 0.791 for CV. There was no significant correlation between AV/CV ratio and cortisol post-DST. An AV/CV ratio ≥ 1 demonstrated low sensitivity (52%) and specificity (48%) for ACS prediction. Although a ratio ≥ 3 was highly specific (> 90%), its sensitivity was limited (17%).

Our study did not show a correlation between AV/CV ratio and the presence of ACS, contrasting earlier promising studies.