Performance of Multimodality Imaging in the Characterization of Adrenal Masses: A 5-Year Retrospective Study

Abstract: Background: The rise of high-resolution cross-sectional imaging has led to a surge in adrenal incidentalomas, creating a diagnostic challenge for clinicians. Distinguishing benign adenomas from malignant tumors is essential to prevent unnecessary surgical interventions. Methods: Our team conducted a 5-year retrospective study (2020–2024) at the Avicenna Military Hospital in Marrakech, focusing on 60 patients with adrenal masses. The diagnostic workup involved unenhanced CT, multiphase washout CT (with a 15-minute delayed phase), and 1.5T MRI using chemical-shift sequences. Radiological findings were compared against histopathology or long-term clinical stability.  Results: Our cohort (mean age 50 years; 63.3% female) predominantly presented with incidentalomas (43.3%). Imaging accurately identified 42 benign and 18 malignant/suspicious lesions. CT densitometry (≤10 HU) and absolute washout (>60%) achieved 100% specificity for adenomas. In cases where CT was indeterminate, chemical-shift MRI served as a non-invasive “virtual biopsy,” demonstrating a significant signal intensity index drop. Conversely, malignancy was associated with size >4 cm and slow contrast clearance (washout <40%). Conclusion: The synergy between CT washout and MRI chemical shift provides a highly reliable diagnostic framework, significantly reducing the morbidity associated with invasive biopsies.