Stress-rest calf muscle perfusion: a functional diagnostic test for peripheral arterial disease (PAD)

外周动脉疾病（PAD）影响近800万人，在美国每年花费超过210亿美元。与 由于腿部血液供应减少，一些患者会出现小腿疼痛或行走疲劳。虽然PAD 可以通过踝关节低血压和狭窄的解剖成像（MRI或CT）可靠地检测到 为了选择最佳的治疗方法，我们需要一种非侵入性的测试来评估小腿肌肉功能。 在这个项目中，我们建议使用高分辨率磁共振成像（MRI）来测量血液 在不同组的小腿肌肉中进行灌注，并在低负荷和高负荷后重复测量 锻炼小腿肌肉。这种负荷-静息成像方法是评价冠状动脉病变的标准治疗方法。 疾病（CAD），从未成功应用于PAD。我们的初步结果显示 的肌肉灌注之间的健康和PAD患者，因此很大的前景的技术。在这4年中， 项目，我们将首先完善灌注成像方法，验证其可重复性，然后比较小牛 PAD患者与健康年龄匹配的健康对照的肌肉灌注测量。该比较 将测试检测PAD患者功能异常的可行性。基线扫描后，PAD 患者将接受为期12周的监督运动治疗，然后进行治疗后的MRI扫描。比较 将指示治疗如何改善小腿肌肉灌注， 以及这种灌注变化如何与患者行走能力的增加相关。 该项目的长期目标是为PAD患者开发一种改进的诊断测试， 预测谁将从治疗干预中受益。腓肠肌的负荷-静息灌注研究可作为临床应用的一种新方法。 与常规外周MRA联合进行，以评估血管狭窄的功能意义。 与常规进行的心脏应力成像方法一样，改善了小腿功能测量 灌注也应该证明在测试和开发改进的治疗方法中是有用的。

Peripheral arterial disease (PAD) affects nearly 8 million people and costs >$21B in the U.S. per year. With reduced blood supply to their legs, some patients experience calf pain or fatigue with walking. Although PAD can be reliably detected by a low ankle blood pressure, and anatomic imaging (MRI or CT) of the narrowing arteries, to select the best treatment approach, we need a non-invasive test to assess calf-muscle function. In this project, we propose to use high-resolution magnetic resonance imaging (MRI) to measure blood perfusion in different groups of calf muscle, and repeat the measurement after a low-load and a high-load exercise of calf muscle. This stress-rest imaging approach is standard of care for evaluation of coronary artery disease (CAD), and has never been successfully applied to PAD. Our preliminary results show distinct patterns of muscle perfusion between healthy and PAD patients, and thus great promise of the technique. In this 4-year project, we will first refine the perfusion imaging method, verify its reproducibility, and then compare the calf muscle perfusion measures in PAD patients against healthy age-matched healthy controls. This comparison will test the feasibility of detecting functional abnormality in PAD patients. After the baseline scans, the PAD patients will undergo a 12-week supervised exercise therapy, and then a post-therapy MRI scan. Comparison of the pre- and post-therapy measurement will indicate how the therapy improves the calf-muscle perfusion, and how this perfusion change correlates with increase in patient’s walking ability. The long term goals of this project are to develop an improved diagnostic test for patients with PAD to predict who will benefit from therapeutic intervention. The stress-rest perfusion studies of calf muscle can be performed in conjunction with routine peripheral MRA to assess the functional significance of vascular stenosis. As with the routinely performed cardiac stress imaging methods, improved functional measures of calf perfusion should also prove useful in the testing and development of improved therapeutic approaches.