Diffusion MRI Tractography of the Human Heart in vivo Reveals Differences in Myofiber Organization at End-Diastole & End-Systole

Choukri Mekkaoui¹, Sonia Nielles-Vallespin², Peter Gatehouse², Marcel P. Jackowski³, David Firmin², David E. Sosnovik

Diffusion Tensor MRI (DTI) of the heart in vivo is complicated significantly by cardiac motion. Here, for the first time, we perform DTI tractography of the human heart in vivo without the need for image interpolation or transformation. Myofiber tracts were derived from 3D in vivo DTI datasets obtained at end-diastole and end-systole. We show, for the first time, that robust in vivo tractograms of the human heart can be derived with a scan duration of less than 20 minutes. In addition, we show that myofiber orientation in the subepicardium increases in obliquity during systole as the myocardium contracts.