Purpose: To evaluate the characteristics of different adrenal nodules using Spectral Detector Computed Tomography (SDCT) and to investigate the ability of single-phase SDCT to differentiate benign from malignant adrenal lesions.
Materials and Methods: All portal-phase abdominopelvic examinations that were performed on an SDCT scanner between April and December 2017 were reviewed for presence of adrenal lesions. Only patients with a standard of reference (previous CT examination / multiphase CT / multiphase MRI) were included in the study. Attenuation measurements of the adrenal lesion and the normal contralateral adrenal on the conventional images, the iodine density map, the virtual non-contrast (VNC) images and virtual monoenergetic (VME) images of SDCT were obtained. An estimation of enhancement was calculated as the attenuation at the conventional images divided by the attenuation at VNC images. The spectral slope was calculated as (attenuation at 40keV VME - attenuation at 100keV VME images)/60. For statistical assessment, ANOVA with Tukey post-hoc for multiple comparisons was used.
Results: 33 lesions/patients were included in this study. According to the standard of reference, the lesions were divided to benign (adenomas) and malignant (metastases). While the Iodine density and the spectral slope did not differ significantly between benign and malignant lesions (p>0.05), the benign lesions had significantly lower HU values (mean 11.3) on the VNC images as compared to malignant lesions (mean 34.1, p<0.001). In addition, the estimation of enhancement was much higher for benign lesions (p<0.001).
Conclusion: Based on VNC images, adrenal adenomas and metastases demonstrate different HU values and estimated enhancement. VNC images from single-phase SDCT can assist in the characterization of incidental adrenal lesions.
