Dynamic Magnetic Resonance Selective Angiography

描述（由申请人提供）： 心脏病和中风主要是由动脉狭窄引起的。自20世纪50年代以来，X射线血管造影一直是诊断动脉狭窄的存在和意义的主要方法。虽然非常有用，但X射线血管造影术是侵入性的，并且通常需要大剂量的肾毒性造影剂。我们已经开发出一种新的MRI技术，它产生类似于X射线血管造影术的电影，无创，无造影剂。该技术涉及对众所周知的稳态自由进动（SSFP）MRI脉冲序列的特定更改。这种新技术，我们称之为“动态磁共振选择性血管造影术”（DMRSA），涉及在移动的血液中激发质子，因为它们在空间中穿过一个切片，同时采集二维投影图像，当血液填充远端脉管系统及其分支时，可以直接可视化血液。该技术的效率本质上是高的，因为激励和成像是同时执行的，并且因为随着血液流过激励切片，新的自旋被连续地“泵送”到远端脉管系统中。以电影（电影）格式采集图像，以便直接可视化脉动血流。与侵入性血管造影一样，DMRSA允许选择性地询问特定的血管。我们显示的初步数据表明，血液可以可视化后，旅行到16厘米外的激励切片，并直接观察到的时间填充的分支血管。我们表明，我们已经制定了一个基本的物理原理的理解，足以让我们修改的基本DMRSA脉冲序列，以这样一种方式，我们的早期实现的技术特征的文物被消除。我们显示了一个病人的主动脉和肾动脉的图像示例，其可视化方式与X射线血管造影相同。我们显示了大量的动物数据，有力地表明，DMRSA可用于非侵入性地确定动脉狭窄的功能意义。根据我们的初步数据，我们相信这项技术有广泛的潜在应用。我们建议优化DMRSA图像质量（目标1），以测试的假设，动脉狭窄的功能意义，可以通过比较血管充盈距离药理学应力下的休息（目标2），并评估DMRSA的能力，以非侵入性检测冠状动脉疾病（目标3）。

DESCRIPTION (provided by applicant): Heart disease and stroke are caused primarily by arterial stenoses. Since the 1950's X-ray angiography has been the primary method of diagnosing the presence and significance of arterial stenoses. While extremely useful, x-ray angiography is invasive and often requires large doses of nephrotoxic contrast agents. We have developed a new MRI technique which produces cine movie analogous to those of x-ray angiography noninvasively and without a contrast agent. The technique involves specific changes to the well-known steady state free precession (SSFP) MRI pulse sequence. This new technique, which we term "Dynamic Magnetic Resonance Selective Angiography" (DMRSA), involves exciting protons within moving blood as they travel through a slice in space and, simultaneously, acquiring two-dimensional projection images which allow direct visualization of the blood as it fills the distal vasculature and its branches. The efficiency of the technique is intrinsically high both because excitation and imaging are performed simultaneously and because new spins are continuously "pumped" into the distal vasculature as blood flows through the excitation slice. The images are acquired in cine (movie) format such that pulsatile blood flow is directly visualized. Like invasive angiography, DMRSA allows specific blood vessels to be selectively interrogated. We show preliminary data demonstrating that blood can be visualized after traveling up to 16 cm outside the excitation slice, and that temporal filling of branch vessels is directly observed. We show that we have developed an understanding of the underlying physical principles sufficient to allow us to modify the basic DMRSA pulse sequence in such a way that artifacts characteristic of our early implementations of the technique are eliminated. We show example images in a patient in which the aorta and renal arteries are visualized in the same manner as in x-ray angiography. We show large animal data strongly suggesting that that DMRSA can be used to noninvasively determine the functional significance of arterial stenoses. Based on our preliminary data we believe this technique has wide potential application. We propose to optimize DMRSA image quality (Aim 1), to test the hypothesis that the functional significance of arterial stenoses can be determined by comparing vessel filling distances under pharmacologic stress to those at rest (Aim 2), and to evaluate the ability of DMRSA to non-invasively detect coronary artery disease (Aim 3).