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，通常 由于血糖水平升高而导致的糖尿病。如果不治疗，PAD可能会导致血管阻塞 血管，导致组织死亡和可能的肢体截肢。约有1000万美国人受到影响 按下肢垫。在其他风险中，PAD的风险在患有以下疾病的人中显著增加 糖尿病是美国第七大死因。糖尿病患者的缺血性事件发生率较高 与可比的非糖尿病人群相比，患有PAD的人更容易患上PAD。当前用于诊断和监控PAD的工具 糖尿病患者依赖踝臂指数(ABI)。然而，ABI检测垫的灵敏度较低， 可能不会显示很大比例的无症状患者伴有PAD的隐性狭窄。目前，CT 血管造影术(CTA)因其操作简便、快速、快速等优点而受到血管外科医生的青睐，已被广泛接受。 诊断性和可重复性的图像质量，检测PAD的侵入性更小。然而，重复垫片 出于长时间电离辐射暴露和高剂量等安全考虑，CTA检查是不可取的 碘造影剂。一种安全可靠的成像方式，可以准确地显示整个 外周血管系统，是非常需要的。无对比磁共振血管造影术(NC-MRA) 注射Gd造影剂，无创，无辐射将是理想的诊断和随访- Up工具，适用于糖尿病患者使用和不使用PAD。目前的NC-MRA技术允许描述整个 外周血管成像；然而，与CTA相比，目前的NC-MRA有以下局限性： 空间分辨率较低、检查时间延长、诊断图像质量不可重现、伪影以及 使用支架和搭桥等外科设备的PAD患者的随访限制。该项目的目标是 开发一种先进的新鲜血液成像(FBI)，用于快速、安全、稳健、诊断、可重复性的NC-MRA和 一种创新的、自由呼吸、无门控、非减影的NC-MRA技术，使用3D超短TE(UTE) 对使用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。 使用一种新的非对比剂MR灌注(NC-MRP)技术。这项为期五年的计划包括最初的两个项目- 一年的技术开发和优化，随后进行的临床评估研究将验证两者 高级FBI、3D UTE和NC-MRP在有无PAD的糖尿病患者中的应用 外科手术器械。我们的具体目标如下：目标1A：发展一支以Ky-kz为中心的先进联邦调查局 具有新的指数重聚焦翻转角度的轨迹；目标1B：开发自由呼吸、无门控、非门控的 减影3D UTE NC-MRA技术；目标2：发展NC-MRP技术以测量微结构 以及目标3：比较先进的FBI和3D UTE的诊断准确性 在AIMS 1中开发，并在AIM 2中用NC-MRP评价糖尿病伴或不伴PAD的微血管 CTA/DSA。我们还将把微血管测量与不同水平的糖尿病患者的糖化血红蛋白和ABI联系起来。

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.