PCASL with a clinically practical ischemia-hyperemia protocol for use in critical limb threatening ischemia

Motivation: Lower-limb vascular imaging used in advanced peripheral arterial disease PAD) is limited to luminography with no functional tissue perfusion data. Goal(s): MRI ASL perfusion quantification is a contrast agent free technique that promises to be a novel imaging biomarker for tissue viability. However, current implementations have several limitations, including low signal-to-noise and the need for a substantial period of hyperemia to induce measurable perfusion in the muscle. Approach: We aimed to develop an abbreviated, clinically-practical ischemia-hyperemia paradigm to measure perfusion, and to evaluate this in volunteers. Results: A 2-minute period of ischemia produced hyperemia a doubling of baseline perfusion, sustained for 30 seconds. Impact: Quantitative perfusion imaging with pseudocontinuous arterial spin labelling can be achieved in the lower limb with an ischemia-hyperemia paradigm with 2 minutes of ischemia. This clinically applicable technique can be used in the assessment of peripheral arterial disease.