Nonenhanced 3T QISS MR Angiography of the Peripheral Arteries

 描述(申请人提供)：外周动脉疾病(PAD)是全身性动脉粥样硬化的一种潜在的衰弱表现，影响着全球超过2亿人。准确的诊断对疾病的处理很重要，并提供有用的预后信息。CT血管成像(CTA)因其操作简单、应用广泛，已成为血管外科医生评价PAD的首选方法。然而，除了不想要的CTA X射线照射外，PAD患者中还有近40%的肾功能受损。在这类患者中，以碘为基础的CT造影剂存在造影剂诱发肾病的风险。由于之前在NIH 1R01HL096916资助的努力，QISS非增强MRA(NEMRA)技术被开发为CTA和对比度增强MRA(CEMRA)的更安全、简单的“按钮”非增强替代方法。然而，还没有Nemra技术在3Tesla被证明有效，这被广泛认为是CEMRA的最佳场强。为了利用3特斯拉的高信噪比提升，需要克服与高比吸收率(SAR)和恶化的B1场均匀度相关的严重图像质量限制。该项目旨在解决这些挑战。它将通过提供最佳的介入治疗策略选择来改善患者的预后，而不考虑患者的年龄、糖尿病的存在、 心律失常、金属植入物或肾功能损害。此外，它将极大地提高影像检查的安全性，并避免需要进行肾功能测试。这个为期五年的项目包括最初两年的技术开发和优化阶段，随后是一项为期两个地点的研究，将验证和确定3T QISS MRA和外周CTA在PAD诊断和介入治疗中的相对实用性。我们的具体目标如下：1.开发对磁化率伪影和B1场不均匀不敏感的QISS技术，并针对3特斯拉遇到的较高比吸收率进行优化。这些技术将在现实的流动幻影、健康受试者和PAD患者中进行评估。2.将完整的QISS外周动脉检查的扫描时间减少到5分钟以下，以优化程序效率和患者舒适度，同时保持图像质量和准确性。3.建立与心电门控QISS MRA图像质量相匹配的非门控QISS技术。4.以数字减影血管造影为参照标准，比较QISS MRA在3特斯拉(采用AIMS 1和AIMS 2中开发的技术)对PAD和CTA的诊断准确性。一个辅助目的是比较房颤患者的UNQISS(在AIM 3中开发)和CTA。

 DESCRIPTION (provided by applicant): Peripheral arterial disease (PAD) is a potentially debilitating manifestation of systemic atherosclerosis affecting more than 200 million people worldwide. Accurate diagnosis is important for managing the disease and confers useful prognostic information. CT angiography (CTA) has become the preferred modality of vascular surgeons for the imaging evaluation of PAD, because of its simplicity and widespread availability. However, in addition to unwanted x-ray exposure from CTA, there is a nearly 40% prevalence of impaired renal function in patients with PAD. In such patients, iodine-based CT contrast agents pose a risk for contrast-induced nephropathy. As a result of efforts previously funded under NIH 1R01HL096916, the QISS nonenhanced MRA (NEMRA) technique was developed as a safer, simple "push button" nonenhanced alternative to CTA and contrast- enhanced MRA (CEMRA). However, no NEMRA technique has yet proven effective at 3 Tesla, which is widely considered the optimal field strength for CEMRA. In order to take advantage of the large signal-to-noise boost at 3 Tesla, severe image quality limitations relating to high specific absorption rate (SAR) and worsened B1 field homogeneity need to be overcome. This project aims to solve these challenges. It will improve patient outcomes by providing optimal selection of interventional treatment strategies irrespective of patient age, presence of diabetes, arrhythmia, metallic implants, or renal functional impairment. Moreover, it will greatly improve the safety profile of the imaging examination and avoid the need for renal function testing. This five-year project consists of an initial two-year technical development and optimization phase, followed by a two-site research study that will validate and ascertain the relative utility of 3T QISS MRA and peripheral CTA for the diagnosis and interventional management of PAD. Our specific aims are as follows: 1. To develop QISS techniques that are insensitive to magnetic susceptibility artifacts and B1 field inhomogeneity, and are optimized for the higher specific absorption rates encountered at 3 Tesla. These techniques will be evaluated in realistic flow phantoms, healthy subjects and patients with PAD. 2. To reduce the scan time for a complete QISS peripheral arterial study to less than five minutes so as to optimize procedural efficiency and patient comfort, while maintaining image quality and accuracy. 3. To develop ungated QISS techniques which match the image quality of ECG-gated QISS MRA. 4. To compare the diagnostic accuracy of QISS MRA at 3 Tesla (using techniques developed in Aims 1 and 2) for PAD compared with CTA, using digital subtraction angiography as the reference standard. A subsidiary aim is to compare UnQISS (developed in Aim 3) with CTA in patients with atrial fibrillation.