DIFFUSION ENHANCED MAGNETIC RESONANCE IMAGING MICROSCOPE

磁共振成像(MRI)已成为金标准技术 用于临床解剖的非侵入性体内可视化。然而，这是 对于MRI在显微可视化中的应用还不能说 生物组织和单细胞。标准的磁共振成像技术是有限的 在各种因素的分辨率中，最重要的是扩散， 磁化率差异和本征核磁共振线宽。它是 普遍认为，扩散是影响 限制了核磁共振在生物样品中的分辨率。大多数计算 将标准MRI技术的实际限制设置在(10)量级 微摩尔)3。 我们提出了一种核磁共振显微镜，它可以分辨细胞，无论是单个细胞还是 在组织内，以及亚细胞结构中。这是基于 扩散增强信号强度和分辨率(Desire)实验 由Lauterbur和他的同事描述的，使用了微观效果 以从小于以下体积的体积放大MRI信号 使用标准的磁共振成像技术是可能的。 在Desire技术中，自旋通过一个小区域扩散到 它们的周围将磁化存储在体素之外，并使用 信号从小体积提高信噪比。 计算表明，在有利条件下，信号放大为 可能高达6个数量级。小型平版印刷术- 构建的磁共振表面线圈将用于实施此实验 利用扫描隧道技术发展起来的定位技术 显微镜。 本提案的目标是构建和测试Desire MRI 生物显微镜分辨率约为(1微摩尔)3 样本。

Magnetic resonance imaging (MRI) has become the gold-standard technique for non-invasive in-vivo visualization of clinical anatomy. However this cannot be said for MRI's application to microscopic visualization of biological tissues and single cells. Standard MRI techniques are limited in resolving power by a variety of factors, most importantly diffusion, magnetic susceptibility differences, and intrinsic NMR linewidth. It is generally agreed that diffusion is the most egregious of the factors to limiting the resolution of MRI in biological samples. Most calculations place a practical limit on standard MRI techniques on the order of ( 10 micromole)3 in these samples. We propose a MRI microscope which will resolve cells, both singly or within tissues, as well as sub-cellular structures. This is based on the DESIRE (Diffusion-Enhanced Signal Intensity and REsolution) experiment described by Lauterbur and colleagues which uses the microscopic effects of diffusion to amplify the MRI signal from volumes smaller than those possible with standard MRI techniques. In the DESIRE technique, diffusion of spins through a small region to their surroundings stores magnetization outside the voxel and uses that signal to enhance the signal-to-noise ratio from the small volume. Calculations show that for favorable conditions signal amplification as high as 6 orders of magnitude may be possible. Small lithographically- constructed MRI surface coils will be used to implement this experiment utilizing positioning technology developed in scanning tunnelling microscopy. The goal of this proposal is the construction and testing of a DESIRE MRI microscope capable of about (1 micromole)3 resolution on a biological sample.