Adrenal nodule: does computed tomography outperform chemical shift magnetic resonance imaging in differentiating benign versus malignant?

Abstract Background The radiologist faces the dilemma of characterizing adrenal lesions, especially in oncology patients, as this finding can alter the patient’s management and prognosis. The objectives of this study were (1) to evaluate and compare the diagnostic accuracy of CT and MRI in distinguishing benign adrenal adenomas from malignant masses employing CT adrenal protocol and Chemical shift Imaging (CSI) in MR scans, and (2) to establish a standard reporting approach/chart/algorithm for adrenal lesions based on the findings of the CT scan and/or MRI. Methods This prospective study data was obtained from 80 patients. On CT scan, the unenhanced HU value, absolute, and relative percentage washout were calculated using a 10-min delay. On MRI, signal loss on chemical shift images was visualized and quantified. Benign lesion −< 10 HU on an unenhanced scan, macroscopic fat, homogenous attenuation value, no enhancement, APW/RPW of 52%/37%, stable over a 1-year interval, loss of signal on CSI with SII of > 16.5%. The rest were either confirmed by biopsy or resection. Results Benign adenomas were the most common, the majority being lipid-rich. Sensitivities and specificities—cut-off size of 4 cm (85%, 77%), cut off < 10 HU (76%, 78%), homogenous enhancement (100%, 78%), APW (88% 85%), RPW (94%, 85%), CSI (88%, 90%). RPW is a statistically significant parameter for characterizing adenomas from non-adenomas. Washout parameters tend to outperform CS-MRI when the density of the adenoma is on the higher side. Conclusions CT and MRI have good accuracy in characterizing an adrenal lesion. In clinical practice, CT can be considered as a one-stop and first-line modality for adrenal imaging. Diagnoses on imaging alleviate the need for biopsies in a large number of patients.