Advancing Endovascular PAD Treatment: Overcoming Critical Knowledge Gaps with MRI-histology

ABSTRACT Peripheral artery disease (PAD) causes severe morbidity as plaques obstruct blood flow, preventing adequate perfusion to limbs, which may result in amputation or death. There are one million interventions to treat PAD per year, emphasizing the high prevalence of this disease. The preferred treatment is percutaneous vascular

interventions (PVI), where vessel plaque is penetrated and threaded (crossed) by a guidewire, followed by a balloon over the wire and/or other adjunctive devices to open the blood vessel. Unfortunately, PVI fails immediately for 20% of patients because the plaque proves impenetrable -- meaning patients are put at risk for

no health benefit. Furthermore, after ballooning open there is damage to the vessel wall and vessels block again within a year for 70% of patients with below-the-knee plaques. These failures then require additional invasive interventions. The difficulties with PVI are frustrating for the clinicians performing the surgery and needlessly

risky for our patients. There is a fundamental gap in knowledge in how to select patients that benefit from PVI and how different preparation devices alter vessel wall injury. We propose a two-pronged approach: 1) improve patient selection for PVI using a novel MRI-histology based anatomic scoring system that identifies patients with

impenetrable plaques; and 2) improve device selection by identifying devices that reduce vessel wall injury during PVI using histopathologic analysis after PVI in a cadaveric model. Our preliminary data show that our in vivo MRI-histology method can visualize hard plaque components (both calcium and dense collagen) to decipher

individual patients' plaque morphology and determine which plaques are penetrable. Furthermore, our cadaveric model indicates differences in vessel wall injury following different preparation devices using detailed ex vivo plaque analysis post-intervention. Our Specific Aims are: 1. Establish a novel MRI-histology anatomic scoring system that predicts PVI immediate technical failure to

improve patient selection for PVI. We will image patients prior to their PVI with our clinical MRI-histology protocol to prospectively score individual patients’ plaques to predict successful guidewire crossing. 2. Describe the benefits of using orbital atherectomy before balloon angioplasty versus using balloon angioplasty

alone for various plaque types in arteries below the knee. We will randomize amputated legs from PAD patients with calcified below-the-knee arteries to undergo plain balloon angioplasty versus atherectomy preparation device prior to angioplasty. Pre-procedure 3T MRI-histology, intravascular ultrasound, and ex vivo plaque

analysis with histology, will determine vessel wall injury between intervention groups. We will establish a patient selection process for PVI and define vessel wall response with ballooning only versus vessel preparation with atherectomy through histologic analysis of cadaveric lesions. Our study will empower

clinical decision-making toward the safest, most effective strategies to ultimately save patient limbs and lives.