Spectral CT-derived Adrenal Extracellular Volume for Functional Lateralization in Primary Aldosteronism

There is currently a lack of validated noninvasive method for subtyping patients with primary aldosteronism (PA). This study aimed to investigate the feasibility of using spectral CT-derived adrenal extracellular volume (ECV) map for determining functional lateralization in PA.

This study retrospectively included 105 patients with PA [44 with a single aldosterone-producing nodule (APN) as model group, and remaining 61 cases as validation group] and 21 non-PA controls. According to the results of adrenal venous sampling, patients in validation group were further divided into LD (left-sided dominance), RD (right-sided dominance), and ND (no dominant side) groups. Based on histogram analysis of ECV maps, the average ECV distribution histograms of APN and normal adrenal gland (NAG) were plotted, and the probability-weighted volume index of aldosterone-producing lesion (V_p) was calculated for bilateral adrenal glands (V_pL &V_pR).

The average ECV distribution histogram of APNs was significantly lower than NAGs (p<0.001). For (V_pL-V_pR), there were significant differences among LD, RD, ND group, and controls (740.91±505.26 mm³ vs. -615.18 ± 708.82 mm³ vs. 80.88 ± 304.96 mm³ vs. 66.76±264.47 mm³, p<.001). The ROC analysis showed AUCs of (V_pL-V_pR) for differentiating LD with ND or RD with ND were 0.885 and 0.845. The optimal diagnostic accuracy was 77.0% (47/61) for determination of LD, RD, or ND in patients in validation group.

Histogram analysis of adrenal ECV map and its derived parameters can assess the overall aldosterone-producing function of a unilateral adrenal gland, and may assist in determining the functional lateralization.