Bilateral adrenal heterogeneity in contrast-enhanced CT for differentiating nodule-negative primary aldosteronism

In nodule-negative primary aldosteronism (PA), quantitative CT findings in unilateral PA differed from those in bilateral PA. We attempted to identify PA by quantitative parameters of contrast-enhanced CT.

A retrospective search was performed for 81 patients with nodule-negative PA who underwent contrast-enhanced CT between January 2021 and November 2024 and adrenal vein sampling thereafter at XXXX. The test cohort and validation cohort were enrolled separately based on the PA type. The optimal cutoff value for identifying PA was analyzed and calculated in the test cohort, and its diagnostic performance was subsequently evaluated in the validation cohort.

In the venous phase of the test cohort, the SD difference or ratio was significantly higher in unilateral-left PA than in bilateral PA [SD difference: 6.3 (4.4, 8.8) Hu vs. 2.5 (1.5, 4.4) Hu, P < 0.001; SD ratio: 1.2 (1.1, 1.3) vs. 1.1 (1.0, 1.1), P < 0.001]. At a cutoff value of 4.90 Hu, the sensitivity and specificity of the SD difference in predicting PA type were 0.733 and 0.957, respectively. The sensitivity and specificity of the SD ratio were 0.867 and 0.723 at a cutoff value of 1.130, respectively. In the validation cohort, the diagnostic performance of the SD difference in identifying PA type was similar to that of the SD ratio (0.801 vs. 0.917, P = 0.06).

Patients with nodule-negative PA can be further differentiated by bilateral adrenal heterogeneity on contrast-enhanced CT. The SD difference has similar predictive ability as the SD ratio.