3D/4D Ultrashort Echo Time Balanced-SSFP MR Lung Images Reconstructed Using XD-GRASP-Pro

Motivation: Obtaining high-quality images of the lung using proton MRI is challenging due to breathing motion and the short T2* and low proton density of lung parenchyma. Goal(s): Our goal was to demonstrate a free-breathing proton lung MRI approach that maximizes parenchyma and vessel signal in the lungs. Approach: This method combines a 3D ultra-short echo time (UTE) balanced steady-state free precession (bSSFP) pulse sequence with a GRASP-Pro-based reconstruction algorithm applied to respiratory phase-binned data. Results: Image quality was markedly better for SSFP images than for spoiled images, and end-of-exhalation frames reconstructed from 4D images compared favorably with respiratory-triggered images. Impact: A UTE bSSFP radial pulse sequence combined with temporally-constrained reconstruction produces high-signal, high-resolution lung images at end-of-exhalation collected during free breathing. While non-end-of-exhalation reconstruction was less effective, a similar reconstruction algorithm that incorporates motion fields could improve results.