MR DIGITAL SUBTRACTION ANGIOGRAPHY OF LOWER EXTREMITY

本研究的主要目的是发展和评估对比增强磁共振数字减影血管造影（MRDSA）对下肢动脉疾病的快速、无创和准确成像。准确且无创的MRDSA将是评估周围血管疾病的一种经济有效的替代方法。具体目标是1)开发集成的3D和2D MRDSA技术，2)开发外周动脉病理频谱成像策略，3)评估MRDSA在外周血管疾病患者中的临床可行性。MRDSA的三维和二维成像对于周围血管疾病的成像都有各自的优势和局限性。我们计划克服它们的局限性，结合它们的优点。交错螺旋三维技术将开发优化信噪比（SNR），空间分辨率和扫描时间。2D序列将通过hadamard编码，多重投影，超高平面内分辨率，磁化准备和数字滤波进行细化。3D和2D脉冲将集成到一个序列中，以提供快速的高分辨率动脉成像，而不会造成静脉污染。病理生理学决定了造影剂的循环和治疗的影像学需要。因此，MRDSA的数据采集将根据病理生理条件量身定制。患者的疾病模式将通过定时扫描来估计。为了获得最佳的信噪比和空间分辨率以及最小的静脉污染，将确定一种单次追踪MRDSA技术和相应的造影剂注射速率。将发展一种综合成像策略，包括多站丸跟踪采集和单站高分辨率采集，用于广泛的周围血管疾病的成像。通过与x线血管造影在一组外周血管疾病患者中的比较，评估MRDSA的临床可行性。该研究的成功发展将使MRDSA成为一种准确、经济、无创的外周血管疾病评估临床工具。

The broad objective of this research is to develop and evaluate contrast enhanced magnetic resonance digital subtraction angiography (MRDSA) for rapid, noninvasive and accurate imaging of arterial diseases in the lower extremity. Accurate and non-invasive MRDSA would be a cost-effective alternative for evaluating peripheral vascular disease. The specific aims are 1) develop integrated 3D and 2D MRDSA techniques, 2) develop strategies for imaging the spectrum of peripheral arterial pathology, 3) evaluate the clinical feasibility of MRDSA in patients with peripheral vascular disease. Both 3D and 2D acquisitions of MRDSA have advantages and limitations for imaging peripheral vascular disease. We plan to overcome their limitations and combine their advantages. Interleaved spiral 3D techniques will be developed to optimize signal-to-noise ratio (SNR), spatial resolution and scan time. 2D sequences will be refined with hadamard encoding, multiple projections, ultra high in-plane resolution, magnetization preparation, and digital filtering. Both 3D and 2D pulses will be integrated into one sequence to provide fast high-resolution arterial imaging without venous contamination. Pathophysiology determines the circulation of the contrast bolus and the imaging needs for therapy. Accordingly, data acquisition of MRDSA will be tailored to pathophysiologic conditions. Patients' disease patterns will be estimated with a timing scan. A bolus chase MRDSA technique and corresponding contrast injection rate will be identified for optimal SNR and spatial resolution and minimal venous contamination. A comprehensive imaging strategy consisting of multi-station bolus chase acquisition and individual station high-resolution acquisition will be developed for imaging a wide range of peripheral vascular disease. The clinical feasibility of MRDSA will be evaluated by comparing it with x-ray angiography in a group of patients with peripheral vascular disease. Successful development of this research will establish MRDSA as an accurate, economic and non-invasive clinical tool for assessing peripheral vascular diseases.