Narrowing of the Intrapancreatic Portion of the Superior Mesenteric Vein on Spiral CT in the Patients without Pancreatic or Peripancreatic Disease

Lee, Hyun Ju; Han, Joon Koo; Kim, Tae Kyoung; Kim, Kyoung Won; Choi, Byung Ihn

Abstract

BACKGROUND/AIMS: The purpose of this study was to determine the incidence of the narrowing of superior mesenteric vein (SMV) at the level of the uncinate process of the pancreas on spiral CT in the patients with no pancreatic or peripancreatic disease.
METHODS
Among 212 consecutive patients who underwent contrast-enhanced abdominal spiral CT, 175 patients (121 men and 54 women, age range 23~86 years, mean age 55 years) without pancreatic or peripancreatic diseases were included. The shortest diameter of the SMV was measured on every CT scan from the portal confluence to just cephalad to the confluence of the gastrocolic trunk. The case the shortest diameter of the SMV is larger than those in uncinate process by 2 mm, was defined as a focal narrowing. The effect of portal hypertension and slice thickness were also analyzed.
RESULTS
For the 175 patients, we subtracted the shortest diameter of the SMV in unicinate process of pancreas from that of SMV in the caudal portion. The subtract ranged from -9.7 mm to 4.9 mm (mean -0.57 mm+/-2.2). In 55 patients (31%), the shortest diameter in uncinate process of pancreas was smaller than that in the caudal portion of the SMV. The definition of focal narrowing was satisfied in 22 patients (13%). There was no statistically significant difference between the groups with or without portal hypertension (p=0.67) and between the groups with the thin ( >3 mm) slice and the thick ( >or=3 mm) slice (p=0.15).
CONCLUSIONS
Focal luminal narrowing of the SMV in uncinate process of pancreas is frequently observed in the patients without pancreatic or peripancreatic disease. Therefore, it should not be regarded as suggestive finding of vascular invasion of pancreatic carcinoma unless other findings are present.