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Computed tomography of the adrenal glands
Last reviewed: 06.07.2025
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The maximum length of the adrenal glands is 2.1 - 2.7 cm, the right one is often longer than the left. The thickness of the branches should not exceed 5 - 8 mm in cross section. Fusiform or nodular thickening of the adrenal gland and inferior vena cava.
On computed tomography, the adrenal glands are usually clearly differentiated from the surrounding fatty tissue, diaphragm, kidneys, and liver.
Depending on which hormones are produced in excess, the following conditions can be diagnosed: adrenal cortex hyperplasia (androgens), Cohn's syndrome (aldosterone), and Cushing's syndrome (cortisone). Differential diagnosis is made with an upper pole cyst and renal angiomyolipoma. The density of the contents of benign cysts is close to the density of water. In case of heterogeneous enlargement or infiltration into adjacent organs, one can think of metastatic lesions or adrenal cancer. Since lung cancer often metastasizes to the liver and adrenal glands, CT of the chest in such patients should be continued caudally to fully visualize the liver and adrenal glands. Also, paravertebrally, tumors of the sympathetic trunk, which are located near the adrenal glands, can be detected, but are quite rare.
Whenever there is doubt about the benign nature of an enlarged adrenal gland, it is necessary to measure the density of the mass during contrast enhancement. Benign adrenal adenoma tends to wash out the contrast agent more quickly than malignant neoplasms such as metastases and cancer. This technique requires additional scanning at the level of the adrenal glands 3, 10, and 30 minutes after contrast injection.
Malignant neoplasms of the adrenal glands tend to prolong contrast enhancement. This feature can be applied in practice for differential diagnostics. The dynamics of adrenal enhancement has been studied in a large number of studies. At the same time, there is a difference in the absolute and relative peaks of contrast enhancement washout. However, washout is completely the same for different types of tumors. Therefore, only the following parameters are clearly proven and useful for evaluation:
Measurement of adrenal density for differential diagnosis of space-occupying lesions
Unenhanced <11HU => Adenoma
10 min after injection of CS: < 45 HU => Adenoma
30 min after injection of CS: < 35 HU => Adenoma
These three density measurements show how different the values of both types of tumor lesions are. If the density is lower than the values indicated, it is safe to say that there is a benign adrenal adenoma.
In all other cases, benign adenoma cannot be determined with sufficient sensitivity and specificity, so additional studies are required.
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