![]() ![]() You can put all of these important nodal territories together into a cohesive search pattern starting with the upper abdomen and working your way down. To solidify your knowledge, scroll through this set of images on a PACS viewer. These lymph nodes are large, rounded, and have lost their normal fatty hilum. In the coronal images from the same patient, you can really see how many enlarged inguinal lymph nodes there are on both sides compared to the normal example. When compared to normal lymph nodes, the patient below has numerous enlarged inguinal lymph nodes. In the coronal example of the periaortic region below, we can see multiple enlarged lymph nodes around the aorta On CT, enlarged lymph nodes usually look like rounded nodules with soft tissue density. Enlarged lymph nodes become increasingly rounded and lose their characteristic fatty hilum. Lymph nodes are generally measured along their short axis, and typically a size greater than 1 cm is considered abnormal. The clinical context and distribution of the lymph nodes will help to determine the likelihood that enlarged lymph nodes are related to cancer. There are a variety of inflammatory, infectious, and neoplastic causes that result in enlarged lymph nodes. However, this is a common site for cancer to spread and in this scenario, we may find enlarged or abnormal lymph nodes, particularly with rectal and prostate cancers. In a healthy individual, it is unlikely you would see lymph nodes in the space around the rectum. Inguinal lymph nodes are usually relatively small and symmetric. The inguinal region is a common place to see lymph nodes. The pelvic sidewall broadly refers to the space in the pelvis that surrounds the vasculature and includes these lymph nodes. In the pelvic regionĪs we head into the pelvis, we can follow the distribution of the iliac vasculature for the accompanying lymph nodes. This distribution is also nicely seen on coronal images. Next, we can broadly consider the area surrounding the abdominal aorta as periaortic or retroperitoneal. These are broadly referred to as mesenteric lymph nodes and, more specifically, ileocolic lymph nodes in the right lower quadrant heading toward the cecum and terminal ileum. Normally, these look like small, round dots and are often best seen on coronal images. There are lymph nodes that extend out into the small bowel mesentery as well. Peripancreatic region (surrounding the pancreas).Porta hepatis region (around the vessels entering the liver).Gastrohepatic ligament region (between the stomach and liver).Starting in the upper abdomen, we check three locations: ![]() Lymph node territories are named based on their anatomic location (i.e., what organ or structure they are next to or what major blood vessel they are following). Evaluating for abnormal or enlarged lymph nodes is an essential part of any abdominal CT, particularly when staging cancer. ![]()
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