MRI OF RENAL ANATOMY AND FUNCTION IN CHRONIC ISCHEMIA

这项建议的目标是开发先进的MRI技术并在体内进行验证，旨在通过一次检查对肾脏进行全面的解剖和功能评估，并随后将这些技术应用于肾动脉狭窄和慢性肾缺血患者的诊断。通过进一步开发成功的现有超快对比增强磁共振血管成像(MRA)技术，将获得详细的解剖学信息。除了高分辨率的肾血管成像外，MRA序列还将用于获得肾实质的三维图像；相关成像还将实现对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。基于我们使用螺旋k空间轨迹的呼吸分辨电影相衬技术在活体测量肾血流方面的成功技术，我们将设计并验证用于测定肾脏中Gd-DTPA提取分数(EF)的序列。EF将通过测定全身静脉和肾静脉的T1值来测量，这将允许确定Gd-DTPA浓度的差异。使用这些EF测量和我们现有的螺旋相位对比技术确定的肾脏血流值，我们将计算肾小球滤过率(GFR)的单肾脏值，GFR是衡量肾功能的标准指标。所有上述技术，在正常猪体内验证后，将构成单一综合MRI检查的组成部分，该检查将用于诊断慢性肾缺血患者。综合检查的效用将通过将干预前MRI确定的参数与临床结果测量和干预后MRI确定的参数相关联来确定。

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.