Motion‐resolved four‐dimensional abdominal diffusion‐weighted imaging using PROPELLER EPI (4D‐DW‐PROPELLER‐EPI)

Abstract

AbstractPurposeTo develop a distortion‐free motion‐resolved four‐dimensional diffusion‐weighted PROPELLER EPI (4D‐DW‐PROPELLER‐EPI) technique for benefiting clinical abdominal radiotherapy (RT).MethodsAn improved abdominal 4D‐DWI technique based on 2D diffusion‐weighted PROPELLER‐EPI (2D‐DW‐PROPELLER‐EPI), termed 4D‐DW‐PROPELLER‐EPI, was proposed to improve the frame rate of repeated data acquisition and produce distortion‐free 4D‐DWI images. Since the radial or PROPELLER sampling with golden‐angle rotation can achieve an efficient k‐space coverage with a flexible time‐resolved acquisition, the golden‐angle multi‐blade acquisition was used in the proposed 4D‐DW‐PROPELLER‐EPI to improve the performance of data sorting. A new k‐space and blade (K‐B) amplitude binning method was developed for the proposed 4D‐DW‐PROPELLER‐EPI to optimize the number of blades and the k‐space uniformity before performing conventional PROPELLER‐EPI reconstruction, by using two metrics to evaluate the adequacy of the acquired data. The proposed 4D‐DW‐PROPELLER‐EPI was preliminarily evaluated in both simulation experiments and in vivo experiments with varying frame rates and different numbers of repeated acquisition.ResultsThe feasibility of achieving distortion‐free 4D‐DWI images by using the proposed 4D‐DW‐PROPELLER‐EPI technique was demonstrated in both digital phantom and healthy subjects. Evaluation of the 4D completeness metrics shows that the K‐B amplitude binning method could simultaneously improve the acquisition efficiency and data reconstruction performance for 4D‐DW‐PROPELLER‐EPI.Conclusion4D‐DW‐PROPELLER‐EPI with K‐B amplitude binning is an advanced technique that can provide distortion‐free 4D‐DWI images for resolving respiratory motion, and may benefit the application of image‐guided abdominal RT.