Should we use CT or MRI for detection and characterization of benign adrenal lesions?

Computed tomography (CT) and magnetic resonance imaging (MRI) are the main imaging modalities used for analysis of adrenal lesions. We compared the ability of CT and MRI to detect and characterize benign adrenal lesions.

Unenhanced abdominal CT and MRI were performed in 16 patients (age range 39-77), and reviewed by a radiologist with 6years of experience in abdominal imaging. The presence, number, size and structure of each mass were analyzed and compared between the two modalities.

There were 18 adrenal masses in 11 patients, four patients had adrenal hyperplasia (AH), whereas one patient had left-sided AH and right-sided adenoma. Ten masses were≥2cm in diameter, and were perfectly depicted using CT and all MRI techniques. There were nine masses with diameter<2cm detected by CT, three of them were missed using MRI. AH was detected in five patients using CT, but its mild form was missed in one patient using MRI. Four masses with attenuation values of>10Hounsfield units could not be characterized using unenhanced CT, but three of them were characterized using MRI.

CT has higher sensitivity for detection of small adrenal tumours and adrenal hyperplasia than MRI. MRI is an important tool in characterization of adrenal masses that could not be characterized using unenhanced CT.