MRI OF RENAL ANATOMY AND FUNCTION IN CHRONIC ISCHEMIA

该提案的目标是开发和体内验证先进的MRI技术，旨在提供一个全面的解剖和功能评价的肾脏在一个单一的检查，并随后应用这些技术诊断患者的肾动脉狭窄和慢性肾缺血。 详细的解剖信息将通过进一步发展现有的超快对比度增强磁共振血管造影（MRA）的成功技术获得。 除了肾血管系统的高分辨率成像外，还将采用MRA序列获得肾实质的三维图像;还将通过相关成像实现肾皮质和髓质的准确描绘，并将使用半自动计算机化技术快速计算这些区域的体积。 基于我们成功的使用螺旋k空间轨迹的呼吸分辨电影相位对比技术体内测量肾血流量的技术，我们将设计并验证用于确定肾脏中钆-DTPA提取分数（EF）的序列。 将通过测定全身和肾静脉T1值来测量EF，这将允许测定钆-DTPA浓度的差异。 使用这些EF测定和通过我们现有的螺旋相位对比技术测定的肾血流量值，我们将计算肾小球滤过率（GFR）的单肾值，GFR是肾功能的标准测量。 所有上述技术，在正常猪体内验证后，将形成单一综合MRI检查的组成部分，用于诊断慢性肾缺血患者。 将通过将介入前MRI确定的参数与临床结局指标和介入后MRI确定的参数相关联来确定综合检查的效用。

The goal of this proposal is the development and in vivo validation of advanced MRI techniques designed to provide a comprehensive anatomic and functional evaluation of the kidney in a single examination, and the subsequent application of these techniques to the diagnosis of patients with renal artery stenosis and chronic renal ischemia. Detailed anatomic information will be obtained through further development of successful existing techniques for ultrafast contrast-enhanced magnetic resonance angiography (MRA). In addition to high- resolution imaging of the renal vasculature, the MRA sequence will be employed to obtain 3- dimensional images of the renal parenchyma; accurate depiction of the renal cortex and medulla will also be achieved by correlation imaging, and volumes of these zones will be rapidly calculated using semi-automated computerized techniques. Building on our successful techniques for the in vivo measurement of renal blood flow with breathing- resolved cine phase-contrast techniques using spiral k-space trajectories, we will design and validate a sequence for the determination of the extraction fraction (EF) of gadolinium-DTPA from the kidney. EF will be measured by determining systemic and renal venous T1 values, which will allow determination of the difference in gadolinium-DTPA concentration. Using these EF determinations and renal blood flow values determined by our existing spiral phase-contrast techniques, we will compute single-kidney values of glomerular filtration rate (GFR), the standard measure of renal function. All the above techniques, following validation in vivo in normal pigs, will form the components of a single comprehensive MRI exam which will be used to diagnose patients with chronic renal ischemia. The utility of the comprehensive exam will be determined by correlating pre- intervention MRI-determined parameters with both clinical outcome measures and post-intervention MRI-determined parameters.