Rapid T2∗-weighted MRI using multishot EPI with retrospective motion and phase correction in the emergency department
Zhiqiang Li, Melvyn B. Ooi, James A. Murchison, John P. Karis
Abstract
Purpose
Brain MRI is increasingly used in the emergency department (ED), where T2*-weighted MRI is an essential tool for detecting hemorrhage and stroke. The goal of this study was to develop a rapid T2*-weighted MRI technique capable of correcting motion-induced artifacts, thereby simultaneously improving scan time and motion robustness for ED applications.
Methods
A 2D gradient-echo (GRE)–based multishot EPI (msEPI) technique was implemented using a navigator echo for estimating motion-induced errors. Bulk rigid head motion and phase errors were retrospectively corrected using an iterative conjugate gradient approach in the reconstruction pipeline. Three volunteers and select patients were imaged at 3 T and/or 1.5 T with an approximately 1-min full-brain protocol using the proposed msEPI technique and compared to an approximately 3-min standard-of-care GRE protocol to examine its performance.
Results
Data from volunteers demonstrated that in-plane motion artifacts could be effectively corrected with the proposed msEPI technique, and through-plane motion artifacts could be mitigated. Patient images were qualitatively reviewed by one radiologist without a formal statistical analysis. These results suggested the proposed technique could correct motion-induced artifacts in the clinical setting. In addition, the conspicuity of susceptibility-related lesions using the proposed msEPI technique was comparable, or improved, compared to GRE.
Conclusion
A 1-min full-brain T2*-weighted MRI technique was developed using msEPI with a navigator echo to correct motion-induced errors. Preliminary clinical results suggest faster scans and improved motion robustness and lesion conspicuity make msEPI a competitive alternative to traditional T2*-weighted MRI techniques for brain studies in the ED.