Adrenal Metastases

    CT of large adrenal met here and CT/PET of another case here , here, and here, anatomy here.

The adrenal glands are the fourth most common site of metastasis after the lungs, liver, and bone. The most common primary sites are lung, breast, skin (melanoma), kidney, thyroid, and colon cancers. The reported frequency of adrenal metastases depends on the incidence of the primary tumor; however, for each primary malignancy, the frequency of adrenal metastases is different. Some malignancies are more likely to have adrenal metastases. About 50% of melanomas metastasize to the adrenal glands, and 30-40% of breast and lung cancers and 10-20% of renal and gastrointestinal tumors have adrenal metastases.

The imaging phenotype of metastases to the adrenal gland of non-adrenal primary malignancy includes:

• Irregular shape and inhomogeneous nature
• Tendency to be bilateral
• High unenhanced CT attenuation values (>10 HU) and enhancement with intravenous contrast on CT (>40 HU at 30 min after contrast administration)
• Isointensity or slightly less intense than the liver on T-1 weighted MRI and high to intermediate signal intensity on T-2 weighted MRI (representing an increased water content)