BOLD MRI as a Surrogate of Improved Muscle Oxygenation Following Endovascular Therapy for the Treatment of CLI

Inclusion Criteria: * Age \> 18 and \< 90 years * Subject has been informed of the nature of the study and agreed to participate and has signed an IRB approved consent form * Subject understands the duration of the study and its follow-up visit requirements and agrees to comply * Subject has documented chronic limb ischemia in the target limb with Rutherford Category 2-5 and pulse plethysmography (PPG), pulse volume recording (PVRs), TcPO2, ABIs or toe pressures and symptoms that conform to the diagnosis of life-style limiting claudication or critical limb ischemia Exclusion Criteria: * Adult subjects who lack the capacity to consent for themselves * Women who are pregnant or wish to become pregnant during the course of the study. (Women of child-bearing potential must undergo pregnancy testing at the time of enrollment, and be counseled in appropriate measures to avoid becoming pregnant for the duration of the study) * Subjects with contraindications to MR imaging procedures (including the administration of gadolinium based contrast agents) * Subjects suspected to be unable to withstand the reactive hyperemia protocol