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^®.
1) 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.
2) 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 × 1.7 × 1.2 cm and 1.0 × 1.0 × 2.0 cm in size, and the other had one adenoma 0.8 × 1.0 × 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 × 0.6 × 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.