Nonenhanced 3T QISS MR Angiography of the Peripheral Arteries

 描述（由申请人提供）：外周动脉疾病（PAD）是一种全身性动脉粥样硬化的潜在衰弱表现，影响全球2亿多人。准确的诊断对于管理疾病和提供有用的预后信息是重要的。CT血管造影术（CTA）因其简单和广泛的可用性，已成为血管外科医生对PAD进行影像学评价的首选方式。然而，除了CTA不必要的X射线暴露外，PAD患者肾功能受损的患病率接近40%。在这类患者中，碘基CT造影剂存在造影剂肾病风险。作为先前在NIH 1R01HL 096916项下资助的努力的结果，QISS非增强MRA（NEMRA）技术被开发为CTA和对比增强MRA（CEMRA）的更安全、简单的“按钮”非增强替代技术。然而，还没有NEMRA技术被证明在3特斯拉下有效，这被广泛认为是CEMRA的最佳场强。为了利用3特斯拉时的大信噪比提升，需要克服与高比吸收率（SAR）和恶化的B1场均匀性相关的严重图像质量限制。该项目旨在解决这些挑战。它将通过提供介入治疗策略的最佳选择来改善患者结局，而不考虑患者年龄、糖尿病的存在， 心律失常、金属植入物或肾功能损害。此外，它将大大提高影像学检查的安全性，并避免肾功能检查的需要。这个为期五年的项目包括最初的两年技术开发和优化阶段，随后是一项两个地点的研究，该研究将验证和确定3T QISS MRA和外周CTA在PAD诊断和介入治疗中的相对效用。我们的具体目标如下：1.开发对磁化率伪影和B1场不均匀性不敏感的QISS技术，并针对3特斯拉下遇到的更高比吸收率进行优化。这些技术将在真实的血流模型、健康受试者和PAD患者中进行评价。2.将完整QISS外周动脉研究的扫描时间缩短至5分钟以内，以优化手术效率和患者舒适度，同时保持图像质量和准确性。3.开发与心电图门控QISS MRA图像质量相匹配的非门控QISS技术。4.使用数字减影血管造影术作为参考标准，比较QISS MRA在3 T（使用目标1和2中开发的技术）与CTA对PAD的诊断准确性。另一个目的是在房颤患者中比较UnQISS（在目标3中开发）与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.