Radiologic Evaluation

Imaging studies often provide useful information about the nature of adrenal tumors (Figure 10-1). Certain abnormalities suggest adrenocortical carcinomas and may change treatment and surgical approach.

Figure 10-1. A, Computed tomographic (CT) scan of a 54-year-old man with a large right adrenocortical carcinoma. Note the areas of necrosis and hemorrhage. CT scan (B) and a magnetic resonance image (C) of a 65-year-old woman with acute onset Cushing's syndrome. Note the evidence of local invasion into the liver and inferior vena cava and loss of tissue planes (arrows).

Figure 10-1. A, Computed tomographic (CT) scan of a 54-year-old man with a large right adrenocortical carcinoma. Note the areas of necrosis and hemorrhage. CT scan (B) and a magnetic resonance image (C) of a 65-year-old woman with acute onset Cushing's syndrome. Note the evidence of local invasion into the liver and inferior vena cava and loss of tissue planes (arrows).

For diagnosis,

• CT and magnetic resonance imaging (MRI) scans can usually diagnose myelolipoma, cysts, and hemorrhage. CT scans with intravenous contrast or chemically shifted MRI scans using gadolinium help to differentiate between adrenocortical adenomas and carcinomas (Table 10-1).25-33 Combining the information gained from imaging studies along with other diagnostic tests helps to determine whether an adrenal tumor is likely to be malignant. Adrenocortical carcinomas are usually

1. Larger than 5 cm

2. Heterogeneous because of necrosis

3. Irregular and have poorly defined margins

4. Invasive to the upper pole of the kidney or the inferior vena cava

5. Associated with adjacent nodal metastasis or liver metastasis

• MRI helps to identify pheochromocytoma, which enhances on T2-weighted or gadolinium-enhanced images. Adrenocortical carcinomas and metastatic tumors in the adrenal glands, however, also enhance on T2-weighted images.27

• Iodocholesterol scintigraphy (iodomethylnorcho-lesterol [NP-59]) can determine whether an adrenocortical tumor is functional or nonfunctional. Most adrenocortical carcinomas fail to take up iodocholesterol.22 Iodocholesterol scinti-

A/L ratio = ratio of signal intensity of the adrenal mass to the liver; CH = chemical shift; CT = computed tomography; HU = Hounsfield units; MRI = magnetic resonance imaging.

Table 10-1. IMAGING CRITERIA THAT MAY HELP TO DISTINGUISH ADRENOCORTICAL ADENOMA

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