Prevalence and types of main and right portal vein branching variations on MDCT

Our objective was to investigate the prevalence of variant main and right portal vein ramification in a large group of patients.

The study group consisted of 200 patients who underwent consecutive contrast-enhanced abdominal CT examinations performed with an 8-MDCT scanner. Two observers evaluated both thin axial sections and 3D maximum-intensity-projection and volume-rendered images for branching patterns of the main and right portal veins.

Conventional main portal vein anatomy was present in 64.5% of the patients. In 9.5% of the patients, the main portal vein trifurcated into the left portal and right anterior and posterior portal veins. In 23.5% of the patients, the main portal vein divided into a common left portal vein-right anterior portal vein trunk and the right posterior portal vein. Three patients (1.5%) had miscellaneous variations. Twenty-two (16.8%) of 131 patients with conventional main portal vein branching had variant right portal vein branching, most of which was a trifurcation, followed by an abnormally proximal origin of the segment VII vein from the right portal vein.

Variant main portal vein branching seems to be very frequent. Common right anterior portal vein-left portal vein trunk is far more common than trifurcation. Although less frequent, variations also occur in right portal vein branching.