Rapid Fire Abstracts
Xinheng Zhang, PhD
Post-doctoral Scientist
Cedars-Sinai Medical Center
Xinheng Zhang, PhD
Post-doctoral Scientist
Cedars-Sinai Medical Center
Xingmin Guan, PhD
Postdoctorral Fellow
Indiana University
Hsin-Jung Yang, PhD
Assistant Professor
Cedars-Sinai Medical Center
Yuheng Huang, MS
Visiting Graduate Researcher
Radiology and Imaging Sciences, Indiana University School of Medicine
Ghazal Yoosefian
Student
Indiana University School of Medicine
Anthony G. Christodoulou, PhD
Assistant Professor
University of California, Los Angeles (UCLA)
Debiao Li, PhD
Professor
Cedars Sinai Medical Center
Rohan Dharmakumar, PhD
Executive Director
Indiana University School of Medicine
Microvascular injury, comprising of intramyocardial hemorrhage (IMH) and microvascular obstruction (MVO) has emerged as the most severe form of reperfusion injury in MI patients1. CMR is the gold standard for characterizing the microvascular injury, but it is time-consuming and can be challenged by inefficient breath-holds or arrhythmias. We developed a free-breathing, non-ECG gated, motion-resolved whole LV 3D acquisition/reconstruction to assess multiple quantitative measurements (cardiac function, MI, MVO and IMH) to fully characterize microvascular injury within 15 min.
Methods:
Sequence
Design: A free-running, 3D multi-gradient-echo (mGRE) acquisition with IR preparation and Cartesian readout was used to collect image data that was interleaved with training data (Fig. 1). Image Model: Images were represented as a 6-way tensor comprising of 1 spatial and 5 temporal dimensions and then jointly reconstructed based on the LRT framework2,3. Following non-contrast readouts, time-resolved post-Gd acquisitions were performed to capture the Gd kinetics with the last time point used arrive at LGE CMR. Image Reconstruction: The time-resolved data were assigned to 15 bins (~1 min per bin) and the temporal coefficients were determined from training data using Bloch-constrained LRT completion. Data acquisition: Reperfused MIs were created in canine and imaged at weeks 1 (n=12) and 8 (n=9) post MI at 3T MR system with the proposed 3D LRT acquisition and conventional 2D acquisitions. Data Analysis: Left ventricle ejection fraction (LVEF), MI size and transmurality, MVO and IMH size were determined using conventional 2D CINE, Early enhancement and Late enhancement and LGE (2 min, 13 min and 15 min post Gd injection respectively), T2* weighted (T2*w) images (TE=11.42 ms), and compared with 3D LRT counterparts. The 3D and 2D acquisitions were separated/randomized by 2 days to ensure contrast washout between acquisitions. Paired t-tests and linear regressions were used determine differences between the conventional and the proposed approaches. Histological Validation: Trichrome and Prussian Blue staining were used to validate MI and IMH.
Results:
Our findings showed 9 out of 12 animals with microvascular injury in the acute phase and 6 out of 9 animals imaged in the chronic phase who has microvascular injury in the acute phase. Representative CINE, T2*-w and LGE images obtained using conventional and 3D approaches are shown in Fig. 2A&B. Excellent agreement of LVEF, IMH and MI sizes between the approaches are shown in Fig. 2C-F. MVO characterization (both early and late enhancement) were highly correlated (Fig. 3). Notably, the proposed 3D approach showed the advantage of visually discerning temporally resolved (every 1 min) MVO changes with full LV coverage compared to the conventional 2D approach (Fig. 3A).
Conclusion:
The proposed 3D approach enables comprehensive whole LV characterization of acute and chronic reperfused MI without respiratory and cardiac gating within 15 minutes in canine. The approach remains to be validated in patients.
