Sonography of the adrenal glands: normal glands and small masses.

To evaluate sonographic imaging of the normal adrenal glands, anterior transverse and longitudinal scans were made on 200 patients who had no evidence of adrenal disease. In 78 additional patients who were suspected of having adrenal masses, anterior and posterior transverse and longitudinal scanning and longitudinal oblique scanning were done. Anterior transverse scanning proved to be the best single method of scanning the adrenal gland and small adrenal masses. The normal adrenal gland which is 3-6 mm thick and adrenal masses as small as 1.3 cm can be delineated. Although the frequency of visualizing normal adrenal glands (78.5% on the right and 44% on the left) with sonography is not as high as with CT, masses are more readily detected than the normal glands. The accuracy for detecting adrenal masses is very high, with a false-negative rate of only 3%. Sonography can be a useful screening test for many patients who are suspected of having adrenal masses. However, for obese patients the image is degraded and a higher false-positive rate (3.5%) is obtained. CT provides better resolution for such patients.