Periportal Low Density on CT in Patients with Blunt Trauma

K. Shanmuganathan ; S.E. Mirvis ; M. Amoroso

OBJECTIVE: We postulated that the CT finding of periportal low density after acute blunt trauma of the abdomen or pelvis results from elevated central venous pressure caused by rapid expansion of intravascular volume during IV resuscitation or by other trauma-related pathologic changes.

MATERIALS AND METHODS: CT scans and medical records of 58 patients, including 42 with CT evidence of hepatic injury and 16 with periportal low density without CT evidence of hepatic injury, were reviewed retrospectively to determine the extent of liver injury, the extent of periportal low density, and the ratio of the transverse diameter of the inferior vena cava to the transverse diameter of the aorta at the level of the right adrenal gland. The ratio, which served as an indirect measure of central venous pressure, was also measured in 20 randomly selected nontrauma patients with normal findings on abdominal CT scans.

RESULTS: The ratios in 29 patients with CT evidence of liver injury without periportal low density were 0.6-2.0 (mean, 1.22), the ratios in 13 patients with diffuse (six) or focal (seven) periportal low density were 0.8-1.6 (mean, 1.31), and the ratios in 16 patients with periportal low density but no evidence of liver injury were 1.1-2.5 (mean, 1.36). The ratios were not statistically different among these three groups of patients. The ratios were 0.5-1.3 (mean, 0.86) for the 20 nontrauma control patients and were significantly lower than those in the trauma patients (p < or = .05). In all patients with periportal low density, the inferior vena cava remained distended at multiple levels through the abdomen without the variation in size expected from respiration, whereas a change in diameter was always observed on sequential CT sections in the nontrauma group. Among the 16 patients with periportal low density but no hepatic injury, a likely cause for elevated central venous pressure, excluding IV volume expansion, was observed in three.

CONCLUSION: The CT finding of periportal low density after blunt abdominal trauma indicates acute elevation of central venous pressure and does not by itself signify hepatic parenchymal injury, as has been previously reported.