Enhanced CT in differentiating asymptomatic adrenal pheochromocytoma from adrenocortical carcinoma

Purpose To evaluate the effectiveness of arterial and portal-venous phase CT in differentiating asymptomatic adrenal pheochromocytoma (PCC) from adrenocortical carcinoma(ACC). Methods We retrospectively analyzed 44 PCC and 18 ACC patients who received CT scanning and pathological confirmed between January 2018 and 2023. Unenhanced CT, arterial and portal -venous phase CT attenuations, and their absolute and relative enhancement ratios were calculated. Principal component analysis determined factor loadings, and receiver operating characteristic (ROC) curves evaluated diagnostic performance. Results Significant differences were observed for arterial minus portal-venous phase CT attenuation [PCC = 49.2 (102.4) vs ACC=-22.5 (38.9)], indicating contrast washout in PCC versus persistent enhancement in ACC.Significant differences were found for unenhanced CT attenuation in [42.15 (7.2)) vs 33.75 (13.7)], arterial phase [168.75 (150.1) vs 68.8 (47.8)], portal-venous phase [120.95 (37.8) vs 75.4 (29.2)], absolute enhancement ratio of arterial phase [125.5 (143.1) vs 27.75 (36.3)], relative enhancement ratio of arterial phase [3.07 (4.02) vs 0.63 (0.9)], absolute enhancement ratio of portal-venous phase [76.3 (40.0) vs 39.3 (15.5)], relative enhancement ratio of portal-venous phase [1.8 ( 1.2) vs 1.1 (0.5)]. ROC curves showed optimal cut-off values were arterial (101 HU) and portal-venous phase (98.5 HU), absolute enhancement ratio of arterial phase (54.8 HU), relative enhancement ratio of arterial phase (1.29), absolute enhancement ratio of portal-venous phase (49.2 HU), and relative enhancement ratio of portal-venous phase (1.31). Conclusion Arterial and portal-venous phase CT attenuation, and their corresponding absolute and relative enhancement ratios effectively differentiate asymptomatic PCC from ACC, provide valuable non-invasive guidance for clinical management.