The purpose of this study is to determine if an MRI technique called Blood Oxygen Level Dependent, or BOLD, can be used to evaluate blood flow in the leg before and after treatment with standard endovascular therapy in patients with chronic lower limb ischemia.

This study is a prospective single arm, open label registry to evaluate the feasibility of blood oxygen level dependent (BOLD) magnetic resonance imaging for the assessment of a potentially new functional surrogate of altered lower limb skeletal muscle oxygenation after a successful percutaneous endovascular intervention. Baseline MRI assessment using the BOLD technique will be performed on qualified subjects prior to undergoing a standard of care endovascular therapy. Post-procedure BOLD-MRI assessment will also be performed at 30 days and either 90 or 180 days post-procedure. Post-MR image acquisition processing and analysis will be performed, using pre-determined algorithms, by a core laboratory.

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