Single-breath clinical imaging of hyperpolarized 129xe in the airspaces, barrier, and red blood cells using an interleaved 3D radial 1-point Dixon acquisition

Abstract

Purpose We sought to develop and test a clinically feasible 1-point Dixon, three-dimensional (3D) radial acquisition strategy to create isotropic 3D MR images of 129Xe in the airspaces, barrier, and red blood cells (RBCs) in a single breath. The approach was evaluated in healthy volunteers and subjects with idiopathic pulmonary fibrosis (IPF). Methods A calibration scan determined the echo time at which 129Xe in RBCs and barrier were 90° out of phase. At this TE, interleaved dissolved and gas-phase images were acquired using a 3D radial acquisition and were reconstructed separately using the NUFFT algorithm. The dissolved-phase image was phase-shifted to cast RBC and barrier signal into the real and imaginary channels such that the image-derived RBC:barrier ratio matched that from spectroscopy. The RBC and barrier images were further corrected for regional field inhomogeneity using a phase map created from the gas-phase 129Xe image. Results Healthy volunteers exhibited largely uniform 129Xe-barrier and 129Xe-RBC images. By contrast, 129Xe-RBC images in IPF subjects exhibited significant signal voids. These voids correlated qualitatively with regions of fibrosis visible on CT. Conclusions This study illustrates the feasibility of acquiring single-breath, 3D isotropic images of 129Xe in the airspaces, barrier, and RBCs using a 1-point Dixon 3D radial acquisition.