Aim: Computed tomography (CT) scanning is commonly used for evaluation of adrenal masses in adults. In this prospective study we evaluated whether adrenal gland masses of less or equal than 20 mm in diameter could be detected by modern abdominal ultrasonography (US).
Method: Between July 1999 and June 2000, 44 consecutive patients with 50 adrenal masses documented by contrast-enhanced CT (left adrenal gland, n = 31; right adrenal gland, n = 19; bilateral, n = 6; median size, 15 [5 +/- 80] mm) and, additionally, 50 patients without CT findings of an adrenal mass were prospectively evaluated by high-resolution US performed by physicians. Based upon CT measurement, 34 adrenal masses were </= 20 mm and 16 were > 20 mm in diameter.
Results: The overall sensitivity of US for the detection of adrenal masses was 96 % (48/50) (94 % [29/31] for left and 100 % [19/19] for right adrenal masses, respectively). The overall specificity of US for the detection of adrenal masses was 92 % (92/100) (90 % [45/50] for left and 94 % [47/50] for right adrenal masses, respectively). Thus, the diagnostic accuracy of US for the detection of adrenal masses is 93 % (140/150). Sensitivity and specificity of US for the detection of adrenal masses </= 20 mm (n = 34) did not differ significantly from those > 20 mm (n = 16).
Conclusion: US is effective for detecting small adrenal masses. In rare cases small masses of the left adrenal gland might be missed and nodular adrenal hyperplasia or retroperitoneal lymph nodes might be misinterpreted as adrenal masses.