Peripheral vascular disease (PVD) caused by smoking, diabetes mellitus, and hypertension, results in limb ischemia in approximately 10% of the population over age 65 years. PVD results in claudication, tissue ischemia, gangrene, and amputation when not treated aggressively. Ninety thousand amputations are performed each year as a result of PVD. Diagnostic methods available at present include invasive techniques such as radiographic angiography, which, because of contrast dye toxicity, can result in serious complications such as renal failure. The diagnostic armamentarium is burgeoning however. Noninvasive techniques such as duplex Doppler and MRI angiography are today allowing surgery to be completed without radiographic angiography and with a high degree of success in selected populations. Patients with Chronic Critical Limb Ischemia (CCLI) are at the highest levels of risk for limb loss and perioperative morbidity and mortality when re-vascularization or amputation is performed. Evidence indicates that current diagnostic methods, again directed primarily at identifying macro-vascular flow impediments, do not adequately assist the surgeon in assessing potential for revascularization in patients with CCLI. As a result, grafting success is much poorer in this population, leading to repeated procedures, often delayed amputation, prolonged rehabilitation, and excessive morbidity and mortality. Astoundingly, when surgeons predicted that amputation stump wounds would not heal, they were wrong 50% of the time, leading one to wonder if their estimation of appropriate level for amputation doesn't tend to be a bit too aggressive. We propose the application of a noninvasive MRI method, Arterial Spin Labeling Perfusion MRI to this problem. Arterial spin-labeling sequences have been developed to study micro-vascular blood flow in the calf and foot. We intend to further the development and application of this technique at high field MRI where improved signal and resolution are likely. We also propose to develop flow indices for the foot, calf, and forearm and compare them with recognized diagnostic standards. Finally, we will apply them prospectively to predict graft patency and wound healing after amputation.
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