CT of the duodenojejunal junction.

To determine the location of the duodenojejunal junction (DJJ) at computed tomography (CT), we retrospectively reviewed 309 consecutive CT examinations. These included 162 men and 127 women (mean age = 57 years old, range = 11-85 years old). Some people received more than one examination. The clinical indications included various kinds of neoplasms, inflammations, congenital lesions, trauma, and other conditions. The DJJ was defined as the first sectioned ascending duodenum whose major part lies to the right side of the crossing part of the inferior mesenteric vein over the immediate beginning of the jejunum. Forty-nine examinations were excluded due to distortion of the DJJ by contiguous pathologic processes or nonadministration of intravenous contrast medium. In 36 examinations, the junctions were not identified. In the successfully identified 224 examinations, the DJJ was located to the left in 75 (33.5%), in the left half in 87 (38.8%), and in the right half or to the right of the vertebral body in 4 (1.8%) examinations. The midline of the DJJ was along the left margin and in the midline of the vertebral body in 53 (23.7%) and 5 (2.2%) examinations. In the anteroposterior direction, it was totally in front of the aorta in 189 (84.4%) and within the projected contour of the aorta in 11 (4.9%) examinations. The midline of the DJJ was along the anterior margin of the aorta in 24 (10.7%) examinations. Its cephalocaudal position was at the upper L1 in 36 (16.1%), lower L1 in 70 (31.3%), upper L2 in 75 (33.5%), and lower L2 in 21 (9.4%) examinations even though it ranged from upper T12 to upper L3.(ABSTRACT TRUNCATED AT 250 WORDS)