Preoperative evaluation on the anatomical structures adjacent to the umbilical portion of the left portal vein using two-dimensional and three-dimensional imagings

Abstract

Objective To study the anatomical variations adjacent to the umbilical portion of the left portal vein (U-point) radiologically and to determine their impact on treatment of hilar cholangiocarcinoma (HCCA). Methods From January 2014 to February 2016, 47 consecutive patients who were diagnosed to suffer from Bismuth type Ⅰ, Ⅱ or Ⅲa HCCA in our institution were retrospectively studied. All these patients underwent enhanced CT examination preoperatively and three-dimensional (3D) models were then reconstructed. Results Any variations of the left biliary system in relation to the U-point were analyzed. The findings showed that: B2 and B3 united above or lateral to the U-point in 31 patients (65.9%); B2 and B3 united medial to the U-point in 4 patients (8.5%); and B4 converged into B3 prior to B2 in 6 patients (12.8%). Rare variations were observed in 6 patients (12.8%). For the confluence patterns of B4: the central type was found in 10 patients (21.3%), the peripheral type in 35 patients (74.5%) and the combined type in 2 patients (4.2%). Analysis of the relationship between B1l and the confluence of B2 and B3 showed the distance to be (31.6±6.2) mm in the above or the lateral patterns and (13.7±4.7) mm in the medial pattern. The difference was significant (P<0.05). The distance from B1l to B4 was (7.1±2.0) mm in the central and combined types but (16.4±4.0) mm in the peripheral type. The difference was significant (P<0.05). The left hepatic artery showed variations in the origin and course pattern in 4 (8.5%) and 6 patients (12.8%), respectively. The two-dimensional (2D) and 3D imagings showed excellent consistency in the evaluation of variations of the left biliary system in relation to the U-point and the left hepatic artery. Conclusions It is very important to know the variations of the left biliary and the vascular systems adjacent to the U-point in preoperative evaluating on resectability of HCCA. An accurate assessment could be accomplished using 2D imaging alone. However, 3D reconstruction is a useful technique to use in complex case with locally advanced tumors. Key words: Umbilical portion of left portal vein; Anatomical variation; Three-dimensional imaging; Hilar cholangiocarcinoma