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，S X线血管造影术一直是诊断动脉狭窄的主要方法。虽然x射线血管造影术非常有用，但它是侵入性的，通常需要大剂量的肾毒性造影剂。我们开发了一种新的磁共振成像技术，它可以无创、无造影剂地产生类似于X射线血管造影术的电影。该技术涉及对众所周知的稳态自由进动(SSFP)MRI脉冲序列的特定改变。这项我们称之为“动态核磁共振选择性血管成像”(DMRSA)的新技术，包括在移动的血液中通过空间切片时激发质子，同时获取二维投影图像，以便在血液填充远端血管系统及其分支时直接显示血液。这项技术的效率本质上很高，因为激发和成像是同时进行的，而且当血液流经激发切片时，新的自旋被持续地“泵入”远端血管系统。图像是以电影(电影)格式获取的，从而脉动的血流被直接可视化。像有创血管造影术一样，DMRSA允许选择性地询问特定的血管。我们给出的初步数据表明，血液在兴奋切片外移动到16厘米后可以被可视化，并且可以直接观察到分支血管的短暂充盈。我们表明，我们已经发展了对基本物理原理的理解，足以允许我们以这样一种方式修改基本的DMRSA脉冲序列，即消除了我们早期技术实现的伪影。我们展示了一个病人的例子图像，其中主动脉和肾动脉的可视化方式与X射线血管成像中的相同。我们展示了大量的动物数据，有力地表明DMRSA可用于无创性地确定动脉狭窄的功能意义。根据我们的初步数据，我们相信这项技术具有广阔的应用前景。我们建议优化DMRSA图像质量(目标1)，检验动脉狭窄的功能意义可以通过比较药物应激状态下的血管充盈距离和静息状态下的血管充盈距离来确定的假设(目标2)，并评估DMRSA非侵入性检测冠状动脉疾病的能力(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).