Revista de citología e histología

An Imaging Study of a Ramification Pattern of Right Posterior Portal Vein Branch

Abstract

Paschalis Gavriilidis, Shi Yuan, Li Weixia, Chai Limin and Shen Baiyong

Background: Our aim was to study the ramification pattern of the Right posterior portal vein branch and to compare our findings to Couinaud classification of the liver. Study design: The study protocol was approved by the institutional review board and written informed consent was obtained from all patients before procedures were performed. Our study includes 104 patients, all were Chinese who underwent helical Computed Tomography during Arterial Portography (CTAP). Subsequently, 3 dimensional portograms were reconstructed to verify the ramification patterns of the portal vein. Portal branching patterns of the right hemiliver were assessed. Results: In all 104 patients examined, three distinct types of anatomical branching patterns of the Right posterior portal vein branch were observed: . Type I: In 52 patients out of 104 (50%), the Right posterior portal branch represents a single trunk forming an arch like pattern and sending multiple branches to segment 6 and segment 7, see Figure 1 and Figure 2. . Type II: In 9 out of 104 patients (9%), the Right posterior portal vein branch showed trifurcation into posterosuperior, posteroinferior, and intermediate branches. The intermediate branch occupied the segmental border between segments S6 and S7, see Figure 3 and Figure 4. . Type III: In 43 out of 104 patients (41%), the Right posterior portal branch bifurcates into Posterosuperior P7 and Posteroinferior P6 third order portal branches as described by C. Couinaud in his homonymous segmental liver classification, see Figure 5 and Figure 6. Conclusions: According to Couinaud classification, the Right posterior portal branch bifurcates into third order Postero superior P7 and Posteroiferior P6 portal branches to supply segments S7 and S6. Our findings showed however, that it happened only in 41% of the cases. In 50% of the findings, the right posterior portal branch represented a single trunk forming an arch like pattern sending multiple branches. The smallest group of 9% showed trifurcation into posterosuperior, posteroinferior, and intermediate branches. Therefore we conclude that there is a discrepancy between the Atlas model of liver segmentation and our imaging findings. Based on these findings we can consider a right lateral sector as a unique segment in 50% of cases.