Image diagnosis of adrenal disorders--I. CT images of control subjects and image diagnosis of primary aldosteronism

Abstract

The shape and size of the adrenals in control subjects without adrenal disorders were studied by computed tomography (CT), and a comparative assessment of diagnostic values of ultrasonography (US) by electronic linear scanner, CT, and adrenal scintigraphy was made on 9 patients with primary aldosteronism. Adrenal imaging by scintigraphy was performed on the 5th and 6th day, or further on the 7th day after the injection of 1 mCi of Adosterol. CT findings of the adrenals in control subjects: Eighty-two % of 100 control right adrenals, and 89% of 100 control left adrenals were detected by CT. Seventy-seven % of the right adrenals were in linear-shape, and the others were in V-shape. The shape of the left adrenals could be classified into triangular-shape (54%), Y-shape (28%) and V-shape (18%). The mean width and thickness of the right adrenals were 28.6 +/- 7.5 mm (M +/- SD) and 3.8 +/- 1.4 mm, respectively. Those of the left ones were 19.4 +/- 5.5 mm and 5.3 +/- 1.8 mm. Image diagnosis of primary aldosteronism: In 2 out of 3 patients examined by US, aldosteronomas were detected. In these 2 patients, one had 2 adenomas 2.8 X 1.7 X 1.2 cm and 1.0 X 1.0 X 2.0 cm in size, and the other had one adenoma 0.8 X 1.0 X 2.0 cm in size. On adrenal scintiscanning under dexamethasone pretreatment (DP), the isotope uptake of aldosteronoma was still seen with the disappearance of the contralateral adrenal in 7 out of 9 cases. In these 7 cases, the laterality of the tumor was confirmed. In one of the remaining 2 cases, the bilateral adrenal images were obtained regardless of DP. In the other case, of which aldosteronoma was the smallest (0.6 X 0.6 X 0.8 cm), the image of the affected adrenal with adenoma as well as the contralateral adrenal disappeared under DP. CT delineated all aldosteronomas in 8 cases examined including 2 cases in which adrenal scintiscanning failed to elucidate the localization of aldosteronoma. These results indicated that the combination of these 3 new image diagnostic methods was available for the detection of aldosteronomas of various sizes.