Surface coil MR imaging of abdominal viscera. Part II. The adrenal glands

Magnetic resonance (MR) imaging of the adrenal glands with a prototype surface coil was compared with conventional body coil images in five healthy volunteers and 15 patients with adrenal disease. The spectrum of abnormalities included five nonfunctioning cortical adenomas, of which two were in hyperplastic glands, four adrenal metastases, three pheochromocytomas, a functioning adenoma, a myelolipoma, and a partially calcified, cystic adrenal mass. In both body and surface coil images, anatomic detail was superior on T1-weighted images compared with T2-weighted images obtained with identical imaging time because of decreased motion artifact and superior contrast. In the T1-weighted studies, high-resolution surface coil images showed a threefold improvement in signal-to-noise ratio (SNR) over body coil images, which was manifest by better intrinsic resolution of small adrenal lesions and clearer definition of the extrinsic relationships of large masses to nearby organs. In addition, inferior vena caval invasion by two right adrenal metastases was better demonstrated using the surface coil than body coil MR or computed tomography (CT). Limitations of surface coil imaging include restriction in the field of view to a single gland and additional time required for patient positioning. Since the sensitivity of surface coils diminishes with depth, gains in SNR were limited in large patients with deeper adrenal glands. Despite these limitations, dramatic improvements in SNR and anatomic resolution indicate that surface coil MR imaging will be competitive with CT for examining the adrenal glands.