Diffusion tensor imaging to assess myocardial microstructure after infarction by magnetic resonance

Graphical AbstractDiffusion tensor imaging (DTI) for the assessment of myocardial microstructure—from myocytes to sheetlets. Top row from left to right: schematic representation of the myocardial tissue components restricting the Brownian motion of the water molecules from microscale to macroscale; from the cellular membranes and interstitial space represented on the left, to the microvessels, sheetlets, and cleavage planes, to the layers of myocytes from the endocardium, to the epicardium as seen on the very far right. Central schematic: DTI allows us to quantify how fast and in which direction the water molecules move within the myocardial tissue components: by deriving eigenvalues (λ1, λ2, λ3) and eigenvectors (ε1, ε2, ε3) from the tensor, DTI provides biomarkers such as myocardial mean diffusivity (MD), fractional anisotropy (FA), helix angle (HA), and sheetlet angle (E2A). When the diffusion of the water molecules is restricted in tightly packed and aligned myocytes, DTI will show reduced diffusivity (low MD, due to reduced apparent speed of the water molecules) and high fractional anisotropy [i.e. FA ranges between 0 and 1, with 0 indicating isotropic, and 1 highly anisotroptic (directional) diffusion, respectively]. Bottom row from left to right: voxel-wise DTI maps are shown for each biomarker: MD, FA, E2A, and HA.Open in new tabDownload slide