Effect of Volume Helical Shuttle Mode with ASiR Technique on the Quality of CT Perfusion Imaging in Liver Tumor

Objective: To investigate the effect of VHS mode with ASi R on the quality of CT perfusion images of liver tumors. Methods: Twenty-eight patients with liver tumor underwent first-pass perfusion CT with volume helical shuttle technique. The raw date had been reconstructed by using FBP, the slice thickness being 2.5 mm. The CT values of aorta and the image noise were recorded for both groups. The parametric maps for the permeability surface(PS), blood volume(BV), blood flow(BF), transit time mean(MTT) were calculated. Paired samples t test or Wilcoxon signed sum test was used to analyze the difference.Image quality was assessed by two radiologists. Results: Compared with FBP reconstruction technique, 40% ASi R demonstrates low image noise((13.20 ±1.65) vs(10.9 ±1.49), P<0.01), with no statistical difference in CT values of aorta((58.33 ±9.19) vs(58.77 ±9.30), P=0.258). All the functional parameters of CT perfusion between two groups, including PS, BV, BF and MTT, showed no statistical difference. 40% ASi R group as quality score(4.14 ±0.36) higher than that of group FBP(3.79 ±0.48), the difference was statistically significant(P=0.001); Conclusion: Application of ASi R demonstrates no influence parameters acquired from CT perfusion with VHS mode in liver tumor, though the noise is lower than FBP.