COMPREHENSIVE MAGNETIC RESONANCE IN PAD

这个子项目是许多研究子项目中利用 资源由NIH/NCRR资助的中心拨款提供。子项目和 调查员(PI)可能从NIH的另一个来源获得了主要资金， 并因此可以在其他清晰的条目中表示。列出的机构是 该中心不一定是调查人员的机构。 外周动脉疾病(PAD)的特征是由于动脉粥样硬化导致的下肢动脉阻塞，阻碍了流向下肢的血液流动。PAD在美国超过800万患者中相当常见。在过去的6年里，我们的多学科研究团队开发了几种新的磁共振测量方法来帮助评估PAD，包括测量股浅动脉的动脉粥样硬化斑块体积，通过31P波谱(MRS)测量运动后磷酸肌酸(PCR)的恢复动力学，以及在运动高峰时首次通过造影剂增强小腿肌肉血流灌注。后者需要格拉络合物，这现在是晚期慢性肾脏疾病的禁忌症，其危险因素与PAD重叠。因此，对于有明显肾功能障碍的PAD患者，在不使用造影剂的情况下量化肌肉血流量和血流储备是可取的。我们假设PAD中的对比和非对比流量储备措施都是可行的，在3T时的表现好于1.5T，并且是可重复性的。因此，具体目标1是开发和测试MRI方法，以量化周围动脉疾病患者在运动高峰时的骨骼肌血流量和血流储备，包括在正常人和PAD中有无造影剂(动脉自旋标记或ASL)。我们假设，这些新的方法将能够检测到已有的PAD治疗方法带来的变化。具体目的#2是测试峰值运动测量小腿肌肉灌注储备和能量学检测经皮血管重建术后PAD患者的变化的能力。25例患者将在血管重建术前、4-8周和6个月后进行研究。具体目标#3是测试峰值运动测量、小腿肌肉灌注储备和能量学检测PAD患者在监督运动治疗后的变化的能力。在为期12周的锻炼计划前后，将对95名患者进行研究。AIMS 2和AIMS 3的所有患者将根据潜在的肾功能首次通过灌注储备或ASL的对比增强测量，运动31P MRS测量聚合酶链式反应恢复动力学，以及包括跑步机运动、VO2测试和6分钟步行在内的功能测量。将检验小腿肌肉灌注的变化和能量变化与功能能力改善之间的相关性。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Peripheral arterial disease (PAD) is characterized by lower limb arterial obstruction due to atherosclerosis that impairs blood flow to the lower limb. PAD is quite common with over 8 million affected individuals in the U.S. Over the past 6 years, our multi-disciplinary team of investigators has developed several new magnetic resonance measures to aid in the evaluation of PAD including atherosclerotic plaque volume measures in the superficial femoral artery, phosphocreatine (PCr) recovery kinetics after exercise by 31P spectroscopy (MRS), and first-pass contrast-enhanced calf muscle perfusion at peak exercise. The latter requires gadolinium chelates which are now contraindicated in advanced chronic kidney disease, whose risk factors overlap with PAD. Quantification of muscle blood flow and flow reserve without the use of contrast would thus be desirable in PAD patients with significant renal dysfunction. We hypothesize that both contrast and non-contrast flow reserve measures in PAD are feasible, perform better at 3T than 1.5T, and are reproducible. Thus, Specific Aim #1 is to develop and test MRI methods to quantify skeletal muscle blood flow and flow reserve at peak exercise in peripheral arterial disease, both with and without contrast (arterial spin labeling or ASL) in normal subjects and in PAD. We hypothesize that these novel methods will be be able to detect changes brought about by established therapies for PAD. Specific Aim #2 is to test the ability of peak exercise measures of calf muscle perfusion reserve and energetics to detect changes in PAD patients after percutaneous revascularization. Twenty five patients will be studied before, 4-8 weeks after, and 6 months after revascularization. Specific Aim #3 is to test the ability of peak exercise measures of calf muscle perfusion reserve and energetics to detect changes in PAD patients after supervised exercise therapy. Ninety five patients will be studied before and after a 12-week exercise program. All patients in Aims 2 and 3 will undergo first pass contrast-enhanced measures of perfusion reserve or ASL depending on underlying renal function, exercise 31P MRS measures of PCr recovery kinetics, as well as functional measures including treadmill exercise, VO2 testing, and 6-minute walk. Correlations will be examined between changes in calf muscle perfusion and energetics with improvements in functional capacity.