Computed Tomographic Characteristics of Presumed Normal Canine Abdominal Lymph Nodes

Abstract

Though identification of lymph nodes is essential in staging cancer patients, little has been reported about the CT features of canine abdominal lymph nodes. The purpose of this retrospective study was to describe the visibility, location, and characteristics of abdominal lymph nodes in abdominal CT studies of dogs considered unlikely to have lymphadenopathy. The relationship between the number of identified lymph nodes and intraabdominal fat ranking, body weight, and slice thickness was also investigated. A total of 19 dogs were included. At least two jejunal lymph nodes and both left and right medial iliac lymph nodes were identified in all dogs. Colic lymph nodes were not identified in any of the dogs. Visualization of all other lymph nodes varied. There were significantly more lymph nodes visible in dogs with more intraabdominal fat (P < 0.0001). No correlation between the number of identified lymph nodes and body weight (P = 0.64) or slice thickness (P = 0.76) was found. Though most of all identified lymph nodes had an elongated shape, a rounded shape was most common in splenic, pancreaticoduodenal, renal, ileocolic and caudal mesenteric lymph nodes. Most lymph nodes had a homogeneous structure before and following the intravenous administration of contrast medium. Some lymph nodes had a slightly irregular structure or were relatively more hyper attenuating in the periphery than centrally before and/or after contrast administration. Mean attenuation before contrast was 37 Hounsfield Units (HU) (range 20-52 HU), and 109 HU after contrast (range 36-223 HU). Findings indicated that the CT visibility, characteristics of different abdominal lymph nodes may be variable in dogs.

Computed tomographic appearance of abdominal lymph nodes in healthy cats

“…The majority of the aortic lumbar (64%), renal (55%), gastric (58%), jejunal (72%), medial iliac (100%), sacral (74%), and inguinal (67%) lymph nodes had an elongated shape, whereas the hepatic (58%), splenic (73%), iliocecal (72%), colic (65%), caudal mesenteric (56%), and pancreaticoduodenal (73%) lymph nodes tended to be rounded. These findings are similar to anatomic reports of cats as well as a previous CT study of dogs . Knowing the expected shape of lymph nodes in each lymph center is important for differentiation of disease.…”

Contrast‐enhanced computed tomography may be helpful for characterizing and staging canine gastric tumors

“…The long axis, short axis, and short axis/long axis of enlarged lymph nodes in the lymphoma and adenocarcinoma cases are summarized in Table . Each lymph node in dogs with adenocarcinoma was slightly larger than values reported in normal canines . Representative figures of enlarged lymph nodes in the lymphoma and adenocarcinoma cases are shown in Figure .…”

“…The enhancement patterns of gastric tumors in the early‐phase and the delayed‐phase were defined as homogeneous or heterogeneous. Lymphadenopathy was determined to be present when the length or width of lymph nodes was more than 5 mm . The presence and location of lymphadenopathy were defined as regional (confined to the drainage area of the involved tumor) or widespread (beyond the area of drainage).…”

Associations Between Dual‐phase Computed Tomography Features and Histopathologic Diagnoses in 52 Dogs With Hepatic or Splenic Masses

“…The following subjective categorical variables were recorded: appearance of the margin of mass (distinct/indistinct), parenchymal homogeneity of mass in precontrast images (homogenous/heterogeneous), hepatic or splenic capsular distortion as a result of mass effect (yes/no), pattern of contrast enhancement (generalized /peripheral), presence of peritoneal fluid (yes/no), mineralization within mass (yes/no), and presence of abnormal hepatic and/or splenic lymph nodes (yes/no) …”