| Resumo: | <h4>Purpose</h4> <p>The diffusion tensor model assumes Gaussian diffusion and is widely applied in cardiac diffusion MRI. However, diffusion in biological tissue deviates from a Gaussian profile as a result of hindrance and restriction from cell and tissue microstructure, and may be quantified better by non-Gaussian modeling. The aimof this work was to investigate nonGaussian diffusion in healthy and hypertrophic hearts.</p> <h4>Methods</h4> <p>Thirteen rat hearts (five healthy, four sham, four hypertrophic) were imaged ex vivo. Diffusion-weighted images were acquired at b-values up to 10,000 s/mm^2. Models of diffusion were fit to the data and ranked based on the Akaike Information Criterion.</p> <h4>Results</h4> <p>The diffusion tensor was ranked best at b-values up to 2,000 s/mm^2, but reflected the signal poorly in the high b-value regime, in which the best model was a non-Gaussian ‘beta distribution’ model. While there is considerable overlap in apparent diffusivities between the healthy, sham and hypertrophic hearts, diffusion kurtosis and skewness in the hypertrophic hearts were more than 20% higher in the sheetlet and sheetlet-normal directions.</p> <h4>Conclusion</h4> <p>Non-Gaussian diffusion models have a higher sensitivity for the detection of hypertrophy compared to the Gaussian model. In particular, diffusion kurtosis may serve as a useful biomarker for characterization of disease and remodeling in the heart.</p>
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