Self-enhancement-based perfusion mapping with contrast-enhanced magnetic resonance imaging for PAD assessment

We developed an automatic self-enhancement-based perfusion mapping (SEPM) method to relatively map the microvascular perfusion level in contrast-enhanced magnetic resonance imaging (CE-MRI) into four categories: hyper-enhanced, isoenhanced, hypo-enhanced, and non-enhanced. These regions are identified based on the relative enhancement from the local pre-contrast arrival frame. We hypothesized that the signal intensity and change in signal intensity of skeletal calf muscles over a course of approximately 10 min of dynamic CE-MRI are measures of perfusion abnormalities that are of importance in patients with peripheral artery disease (PAD). Impairments of the microvascular circulation of the skeletal calf muscles in PAD patients can be quantified by analyzing signal enhancement patterns in CE-MRI. We assessed hypoperfusion in 52 study participants including 35 PAD patients and 17 matched controls. We also investigated PAD subgroups with a known higher risk of adverse outcomes including those with concomitant diabetes mellitus and those who did not complete a graded 6-min treadmill walking test. Our findings show that PAD patients demonstrate a consistently higher rate of hypoperfusion percentages compared to matched controls. Our findings further indicate that each calf muscle group exhibits varying levels of heterogeneity, reflecting non-uniform perfusion dynamics. In five distinct calf muscle groups and averaged over all calf muscle compartments, the average percentage of the hypoperfused regions was lowest in the control group and highest in the more severe PAD groups including treadmill non-completers and those with concomitant diabetes. The quantification of the microcirculation is of importance to assess PAD patients.