Necrosis in postoperative histology has been reported as being specific for adrenocortical carcinoma (ACC) compared to adenoma. We therefore retrospectively analyzed the diagnostic accuracy of the finding of necrosis in preoperative cross-sectional imaging and postoperative histology as a marker for ACC in our patient cohort. Among the 411 adrenalectomies in 396 patients performed between 2008 and April 2022, 30 cases of ACC (7.6%) were identified, with one tumor measuring less than 40 mm excluded. All 45 benign adrenocortical tumors of at least 40 mm in diameter, including Cushing, Conn, and hormonally inactive adenomas, served as controls. Preoperative imaging was available for 40 benign and 27 malignant adrenocortical tumors. In total, 10 of 40 (25%) benign adrenocortical tumors and 22 of 27 (81%) ACCs showed signs of possible necrosis in preoperative imaging. Pathologic examination confirmed necrosis in 1 of 40 (2.5%) benign tumors and in 26 out of 27 (96%) malignant tumors. The specificities of possible necrosis in preoperative imaging and necrosis in histology for diagnosing ACC were 75% and 97.5%, respectively, whereas the sensitivities were 81% and 96%, respectively. Signs of possible necrosis in radiologic imaging and tumor necrosis in histology proved to be very good predictive markers for the diagnosis of malignant adrenocortical tumors.

Background: The adrenal glands are small endocrine organs located in the abdominal cavity, playing a critical role in hormone production. However, they have not been studied using magnetic resonance elastography (MRE), a technique known for its sensitivity to viscoelastic differences in various abdominal organs. While MRE has been successfully applied to assess tissue stiffness in larger organs, its application to the adrenal glands remains unexplored. The purpose of this study is to establish multifrequency MRE for the non-invasive quantification of healthy adrenal viscoelasticity, with the goal of providing reference values that could be used to assess adrenal masses in future research. Methods: In this prospective cross-sectional study, conducted from December 2020 to November 2021 at a tertiary care academic center, we analyzed the adrenal glands of 15 healthy outpatient participants, who were enrolled through convenience sampling, using multifrequency MRE at 3 T. Tomoelastography post-processing was applied at frequencies of 30, 40, 50 and 60 Hz using shear wave speed (SWS) in m/s as a surrogate for stiffness and loss angle of the complex shear modulus in rad for fluidity. Statistical analysis included the coefficient of repeatability (CR) to assess repeatability in a subgroup of twelve participants, intraclass correlation coefficient (ICC) to evaluate interobserver variability between analyses from two independent observers, and the two-tailed Wilcoxon test to evaluate lateral and sex differences as well as the relative increase in sharpness of stiffness maps after applying motion correction. Additionally, correlation analyses were performed to examine the relationship between loss angle and body mass index (BMI). Results: Multifrequency MRE was 100% feasible. Total median SWS and loss angle with their interquartile range (IQR) were 1.31 (1.24–1.33) m/s and 0.84 (0.79–0.91) rad with very good repeatability (CR =0.05/ICC =0.89) and (CR =0.12/ICC =0.73), respectively. Motion correction resulted in a relative increase in SWS sharpness of 12%±12% (P=0.04). Loss angle was negatively correlated with BMI (r=−0.55; P=0.04). No lateral or sex differences were observed. Conclusions: Multifrequency MRE provides direct analysis of viscoelasticity of the adrenal glands on high-resolution elastograms with an excellent repeatability, providing direct analysis of small organs such as the adrenal glands directly on the elastograms. Our study provides first reference values of viscoelasticity of the adrenal gland.