MR evaluation of macro- and micro-vascularity in diabetic peripheral artery disease

外周动脉疾病（PAD）是一种血管管腔狭窄的动脉粥样硬化性疾病， 与糖尿病有关，因为血糖水平升高。如果不及时治疗，PAD可能导致阻塞， 血管，导致组织死亡和可能的截肢。大约有1000万美国人受到影响 下肢PAD。在其他风险中，PAD的风险在患有以下疾病的受试者中显著增加： 糖尿病是美国第7大死亡原因。糖尿病患者的缺血性事件发生率较高 PAD患者比非糖尿病人群的患病率高。目前用于诊断和监测PAD的工具， 糖尿病患者依赖踝臂指数（ABI）。然而，ABI检测PAD的敏感性较低， 可能无法揭示大部分无症状PAD隐性狭窄患者。目前，CT 血管造影术（CTA）由于其简单、快速 诊断和可再现的图像质量，并且用于检测PAD的侵入性较小。尽管如此，PAD一再 由于长时间电离辐射暴露和高剂量等安全性问题，不需要CTA检查 碘造影剂。一种安全可靠的成像模式，可以准确地显示整个 外周血管系统，是急需的。非对比磁共振血管造影（NC-MRA），不 钆造影剂注射、非侵入性和非放射性将是理想的诊断和随访- 有和没有PAD的糖尿病患者的工具。目前的NC-MRA技术允许描绘整个 外周血管成像;然而，与CTA相比，当前NC-MRA存在以下局限性： 低空间分辨率、延长的检查时间、不可再现的诊断图像质量、伪影 使用支架和旁路移植物等手术器械的PAD患者的随访受限。该项目旨在 开发一种先进的新鲜血液成像（FBI），用于快速，安全，稳健，诊断，可重复的NC-MRA， 一种创新的、自由呼吸、非门控、非减影NC-MRA技术，使用3D超短TE（UTE）， 对带手术器械的患者进行随访。此外，还将研究糖尿病足的微血管分布 使用新的非对比MR灌注（NC-MRP）技术。这个为期五年的项目包括最初的两个- 一年的技术开发和优化，随后进行临床评估研究，将验证 在有和无PAD的糖尿病患者中进行高级FBI、3D UTE和NC-MRP， 手术器械我们的具体目标如下：目标1A：开发一个先进的联邦调查局， 目标1B：开发自由呼吸、无门控、无噪声。 目的2：发展NC-MRP技术，测量微血管， 目的3：比较高级FBI和3D UTE的诊断准确性 在目标1中开发，并在目标2中通过NC-MRP评估糖尿病伴或不伴PAD的微血管， CTA/DSA。我们还将微血管测量与各种糖尿病水平的HbA 1c和ABI相关联。

Peripheral artery disease (PAD) is an atherosclerotic disease with narrowing blood vessel lumen, and is often associated with diabetes due to elevated blood sugar level. If left untreated, PAD can lead to blockage of vessels, resulting in tissue death and possible amputation of a limb. About 10 million Americans are affected by lower extremity PAD. Among other risks, the risk of PAD is markedly increased among subjects with diabetes, the 7th leading cause of death in the U.S. The rate of ischemic events is higher in diabetic individuals with PAD than in comparable non-diabetic populations. Current tools for diagnosing and monitoring PAD in diabetic patients rely on ankle-brachial index (ABI). However, ABI has a low sensitivity of detecting PAD and may not reveal a large proportion of asymptomatic patients with hidden stenosis of PAD. Currently, CT angiography (CTA) has gained wide acceptance that is preferred by vascular surgeons due to simple, fast, diagnostic and reproducible image quality, and less invasive for detecting PAD. Nevertheless, repeated PAD CTA examinations are not desired from the safety concerns like long ionizing radiation exposure and high dose iodine contrast medium. A safe and robust imaging modality, which can accurately visualize the entire peripheral vasculature, is critically in need. Non-contrast magnetic resonance angiography (NC-MRA), without a Gadolinium contrast injection, non-invasiveness, and non-radiation would be an ideal diagnostic and follow- up tool for diabetic patients with and without PAD. Current NC-MRA techniques permit depiction of entire peripheral vascular imaging; however, there are following limitations in current NC-MRA as compared to CTA: inferior spatial resolution, prolong examination time, non-reproducible diagnostic image quality, artifacts, and limitation in follow-up of PAD patients with surgical devices such as stents and bypass grafts. The project aims to develop an advanced fresh-blood imaging (FBI) for fast, safe, robust, diagnostic, reproducible NC-MRA and an innovative, free-breathing, ungated, non-subtracted NC-MRA technique using 3D ultra-short TE (UTE) for follow up on the patients with surgical devices. In addition, micro-vascularity of diabetic foot will be investigated using a new non-contrast MR perfusion (NC-MRP) technique. This five-year project consists of an initial two- year technical development and optimization, followed by a clinical assessment study that will validate both advanced FBI, 3D UTE, and NC-MRP on diabetic patients with and without PAD regardless of the presence of surgical devices. Our specific aims are as follows: Aim 1A: To develop an advanced FBI with centric ky-kz trajectory with a new exponential refocusing flip angle; Aim 1B: To develop the free-breathing, ungated, non- subtraction 3D UTE NC-MRA technique; Aim 2: To develop the NC-MRP technique to measure micro- vascularity of the foot; and Aim 3: To compare the diagnostic accuracy of advanced FBI and 3D UTE developed in Aims 1 and evaluate micro-vascularity by NC-MRP in Aim 2 on diabetes with or without PAD with CTA/DSA. We will also correlate micro-vascularity measures with various diabetic levels of HbA1c and ABI.