Abdominal CT: spleen and adrenal glands

Imaging the spleen and adrenal glands

Spleen

The spleen is less complex than the liver and is usually straightforward to evaluate. It is located in the left upper quadrant and has an oval or wedge shape. It generally measures less than 12 cm in length, but a volume estimate is a more accurate way to determine if the spleen is enlarged.

The splenic artery and vein enter the spleen through a central depression called the splenic hilum. The hilum is also associated with ligaments attaching the spleen to the stomach and left kidney, which are not usually visible on CT

In the arterial phase, the spleen often has a wavy pattern of enhancement that is referred to as a zebra-striped appearance. This undulating pattern of enhancement is caused by the contrast making its way through the splenic tissue. Over time this pattern will become less pronounced, and it eventually disappears by the portal venous phase.

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Benign masses

Most lesions in the spleen are benign and incidental, such as cysts or hemangiomas. Cysts do not enhance, and they appear dark compared to the splenic tissue, similar to fluid.

On the other hand, hemangiomas will enhance, and they can be either darker or brighter than the normal splenic tissue.

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Malignant masses

Not all splenic masses are benign. When staging cancer, it is important to carefully evaluate the spleen, as cancers like breast, lung, colorectal, and melanoma can spread there.

Lymphoma commonly involves the spleen and can also cause both an enlarged spleen and masses.

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Adrenal glands

The adrenal glands are paired endocrine organs that are found anterior and superior to the kidneys. The normal adrenal gland is thin and enhances uniformly with a characteristic y-shape.

You may see thickened adrenal glands or nodules, which are often benign. However, both primary cancer and metastatic disease can occur in the adrenal glands. There are dedicated adrenal exams for evaluating suspicious nodules.

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Knowledge iteration

To solidify the key anatomy from this lesson, click on the image below to scroll through a set of images featuring a healthy-appearing spleen and adrenal glands.

1. Looking at the axial images, you can start with the spleen in the left upper quadrant. Notice its smooth contour, normal size, and vascular supply entering the splenic hilum.
2. The adrenal glands lie above and slightly in front of both kidneys, with a characteristic y-shape. The adrenal glands are thin, uniformly enhancing, and without a nodule or mass.
3. Next, review that same anatomy on the coronal images. The spleen is in the left upper quadrant with the artery and vein entering the splenic hilum.
4. The adrenal glands are sitting above the kidneys. See if you can identify the characteristic shape and thin, normal, enhancing parenchyma

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References

• Top 100 CT scan quiz. LITFL

Radiology Library: Abdominal CT: Imaging the abdominal organs and bowel

• Hartung MP. Abdominal CT: Evaluating the liver
• Hartung MP. Abdominal CT: Evaluating the biliary system and pancreas
• Hartung MP. Abdominal CT: Imaging the spleen and adrenal glands
• Hartung MP. Abdominal CT: Mastering the genitourinary system
• Hartung MP. Abdominal CT: Evaluating the lower oesophagus and stomach
• Hartung MP.  Abdominal CT: Imaging the small bowel
• Hartung MP. Abdominal CT: Viewing the peritoneal cavity
• Hartung MP. Abdominal CT: Running the large bowel and appendix

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