Background <p>The value of virtual noncontrast (VNC) images from photon-counting computed tomography (PCCT) for evaluating adrenal lesions and diagnosing adrenal adenomas remains to be clarified.</p> Materials and methods <p>Participants with adrenal masses who underwent unenhanced and portal venous phase PCCT were prospectively included. Portal-venous phase images were reconstructed using conventional VNC (VNC_Conv) and PureCalcium VNC (VNC_PC). We measured two-dimensional (2D) attenuation of adrenal masses at their largest slice on true noncontrast (TNC), VNC_Conv, and VNC_PC images. Three-dimensional (3D) attenuation and radiomic features of adrenal masses were semiautomatically extracted. These parameters were statistically compared, and diagnostic performance for adenomas was evaluated.</p> Results <p>The study included 54 participants (27 females, mean age 45.3 years) with 68 adrenal lesions. Attenuation values on VNC were higher than those on TNC. TNC, VNC_Conv, and VNC_PC attenuation values did not differ between 2D and 3D measurements. The intraclass correlation coefficients of first-order, shape, and texture features between TNC and VNC were 0.671, 0.822, and 0.616, respectively. The sensitivity and specificity of the proposed thresholds (VNC_Conv 25 HU, VNC_PC 20 HU) were higher than those of the previously established threshold of 10 HU in diagnosing adenomas. There was no significant difference between VNC_Conv and VNC_PC in diagnosing adenomas (area under the receiver operating characteristic curve: 0.841 <i>versus</i> 0.838, <i>p</i> = 0.873).</p> Conclusion <p>VNC algorithms from PCCT overestimated CT attenuation of adrenal lesions. Higher thresholds showed better diagnostic performance for discriminating adrenal adenomas from non-adenomas than the established 10 HU.</p> Relevance statement <p>We investigated the application of VNC images from PCCT in adrenal disease. On VNC images, higher thresholds, superior to the accepted 10 HU, are needed for discriminating adenomas from non-adenomas, reducing the need for secondary examinations.</p> Key Points <p><UnorderedList Mark="Bullet"> <ItemContent> <p>This study investigated the value of VNC images from PCCT in adrenal lesions.</p> </ItemContent> <ItemContent> <p>VNC reconstruction overestimated the CT attenuation of adrenal lesions.</p> </ItemContent> <ItemContent> <p>Higher thresholds on VNC images were superior to the accepted 10 HU for differentiating adenomas from non-adenomas.</p> </ItemContent> </UnorderedList></p> Graphical Abstract <p></p>