| Purpose:To explore the methods of visualizing hepatic portal vein in non-contrast-enhanced magnetic resonance portography(NCE-MRP) on healthy volunteers by using true steady-state free-precession(true-SSFP) combined with time-spatial labeling inversion pulse(Time-SLIP), and acquired approximately the best black blood inversion time(BBTI)Materials and Methods:36 healthy volunteers were enrolled in this study and were examined by true-SSFP sequences with Time-SLIP in 1.5T MR scanner. The portographic images were generated from the subtraction between the visualization of liver parenchyma, hepatic and portal venous system and the visualization of just liver parenchyma and hepatic venous system. According to the difference in BBTI of Time-SLIP, four image groups: BBTI of 700 ms, BBTI of 900 ms, BBTI of 1100 ms and BBTI of 1300 ms, were assigned. The quality score of visualization, the grade of hepatic portal vein branches was measured. The signal intensity(SI) of the large vessels as main, right and left portal vein(MPV, RPV and LPV, respectively) and small vessels as the Grade 3 of branches of segments four(P4) and eight(P8) and their vessel-to-liver ratio(VLR) were also compared. Kruskal-Wallis test was used for comparison of qualitative grades, and One-Way ANOVA and SNK test were used for comparison of quantitative data. Results:In 36 volunteers, visualization of the grade 6 of hepatic portal vein was in 28 cases, and the grade 7 was in 10 cases. The cases of visualizing the grade 5 and higher branches and the 4 score images was more than other in BBTI of 1100 ms. In the subtraction, the SI of MPV, LPV, P4 and P8 significantly increased in BBTI of 1100 ms. When BBTI equaled 700 ms, the SI of RPV was lower than others. The VLR of MPV, LPV, P4 and P8 decreased in BBTI of 900 ms, 700 ms, 1100 ms, and 1300 ms. In generally, the SI of MPV was lower than LPV and RPV. The SI of RPV and P8 was higher than LPV and P4 respectively. The VLR of MPV and P4 decreased compared to RPV and P8 respectively. Conclusion:True SSFP with Time-SLIP enabled visualization of the hepatic portal vein of NCE-MRP with subtraction method. The approximately best BBTI preferred 1100 ms. |
