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Two-component diffusion tensor MRI of isolated perfused hearts
E W Hsu1, D L Buckley, J D Bui
1Department of Biomedical Engineering, Duke University, Durham, North Carolina 27708-0281, USA. Edward.Hsu@duke.edu
Abstract:
Nonmonoexponential MR diffusion decay behavior has been observed at high diffusion-weighting strengths for cell aggregates and tissues, including the myocardium; however, implications for myocardial MR diffusion tensor imaging are largely unknown. In this study, a slow-exchange-limit, two-component diffusion tensor model was fitted to diffusion-weighted images obtained in isolated, perfused rat hearts. Results indicate that there are at least two distinct components of anisotropic diffusion, characterized by a "fast" component whose principal diffusivity is comparable to that of the perfusate, and a highly anisotropic "slow" component. It is speculated that the two components correspond to tissue compartments and have a general agreement with the orientations of anisotropy, or fiber orientations, in the myocardium. Moreover, consideration of previous studies of myocardial diffusion suggests that the presently observed fast component may likely be dominated by diffusion in the vascular space, whereas the slow component may include the intracellular and interstitial compartments. The implications of the results for myocardial fiber orientation mapping and limitations of the current two-component model used are also discussed.
Insights
High diffusion-weighting strengths reveal two distinct anisotropic diffusion components in myocardial magnetic resonance diffusion tensor imaging. This finding aids in understanding tissue compartments and improving myocardial fiber orientation mapping.
Area of Science:
- Biomedical Imaging
- Cardiovascular Research
- Diffusion Tensor Imaging
Background:
- Nonmonoexponential MR diffusion decay is observed in tissues like the myocardium at high diffusion-weighting strengths.
- The implications for myocardial MR diffusion tensor imaging (DTI) remain largely unexplored.
Purpose of the Study:
- To investigate the underlying diffusion characteristics in myocardial tissue using a two-component diffusion tensor model.
- To explore the potential of this model for myocardial fiber orientation mapping.
Main Methods:
- A slow-exchange-limit, two-component diffusion tensor model was applied.
- Diffusion-weighted images were acquired from isolated, perfused rat hearts.
Main Results:
- At least two distinct anisotropic diffusion components were identified.
- A 'fast' component with diffusivity similar to the perfusate and a highly anisotropic 'slow' component were characterized.
- These components likely correspond to different tissue compartments (vascular, intracellular, interstitial) and align with myocardial fiber orientations.
Conclusions:
- The study identifies distinct diffusion components in the myocardium, suggesting contributions from vascular, intracellular, and interstitial spaces.
- These findings have implications for enhancing myocardial fiber orientation mapping using MR diffusion tensor imaging.
- Limitations of the current two-component model were also discussed.