Diffusion Anisotropy Corrections for Vessel Size & Microvessel Density Imaging

Jens H. Jensen¹

The standard theories for vessel size imaging (VSI) and microvessel density imaging (MDI) are based on an assumption of isotropic water diffusion. Therefore, the validity of applying these techniques to white matter may be questioned. Here the corrections to the basic VSI and MDI equations due to diffusion anisotropy are explicitly calculated in terms of the diffusion tensor. For the most anisotropic brain regions, the corrections are found to be significant, although not large. These results may relevant for application of VSI and MDI to the assessment of angiogenesis in white tumors.