Perfusion Tensor Imaging of Human Skeletal Muscle

Introduction: The ability to non-invasively measure tissue perfusion is critical for assessing the physiological functions of human skeletal muscle in both healthy and disease states. The traditional techniques to measure tissue perfusion in human muscle are invasive and measure only bulk properties which do not render information on either spatial or temporal heterogeneity. Velocity selective arterial spin labeling (VSASL) MRI has been shown previously to be sensitive to muscle perfusion in humans [1], but does not allow a full exploration of important properties associated with the muscle perfusion, such as perfusion anisotropy and perfusion directions. Perfusion Tensor Imaging (PTI) was proposed in 2004 by Frank and Wong [2] in a study of perfusion anisotropy in the human brain, where VSASL was applied with a spherical velocity encoding scheme similar to that used in diffusion tensor imaging (DTI). The perfusion measurements can then be characterized by a perfusion tensor (P), analogous to the diffusion tensor in DTI, from which the estimates of the mean perfusion, fractional perfusion anisotropy and principle perfusion direction can be derived. This study demonstrates that PTI can also be used to measure perfusion properties of human skeletal muscle.