To investigate the correlation between the DCE-CT imaging biomarkers and histological biomarkers of tumor angiogenesis in adrenal adenomas and non-adenomas for the enhancement mechanism of DCE-CT.

Forty-two patients with 45 adrenal masses including 27 adenomas and 18 non-adenomas diagnosed pathologically were enrolled in this study. The features of DCE-CT (imaging biomarkers) and tumor angiogenesis (histological biomarkers) in adrenal masses were evaluated, and their correlations were explored.

The enhanced features of DCE-CT in adrenal masses were classified: rapid washout group and slow washout group. Type A and C of time density (TD) curves, relative washout rate (Washr) ≥34%, and absolute washout rate (Washa) ≥43% belonged to the rapid group. In contrast, type B, D and E, Washr <34%, and Washa <43% belonged to the slow group. There was significant difference between the biomarkers of DCE-CT in adrenal masses. The rapid group was mainly found in adenomas, whereas the slow was mainly present in nonadenomas. The tumor angiogenesis, histological biomarkers, including microvessel density (MVD), vascular endothelial growth factor (VEGF), and microvascular ultrastructures demonstrated significant difference between the rapid and the slow washout group revealed by DCE-CT. The MVD and VEGF expression in rapid group were remarkably higher than those in slow group. Meanwhile, the tumor angiogenesis was also significantly different between adenomas and nonadenomas. The MVD and VEGF expression were also significantly higher in adenomas than those in nonadenomas. Furthermore, different microvascular ultrastructures were identified between adenomas and nonadenomas, which were in accordance with those between the rapid and the slow group. Microvascular ultrastructures in adrenal adenomas and/or the rapid group showed regular lumens and nonstenosis; more pinocytotic vesicles and fenestrations of endothelium; widening of the intercellular space; uniform thinning and better integrity of basal membrane; regular and uniform thinning, along with less stroma of extra vessel space. In comparison, opposite microvascular ultrastructures, in adrenal nonadenomas and/or the slow group.

The close correlation of DCE-CT imaging biomarkers and histological biomarkers of tumor angiogenesis was found between adrenal adenomas and nonadenomas. Tumor angiogenesis in adrenal adenomas and nonadenomas were shown the different enhancement characteristics at DCE-CT.