Dynamic contrast-enhanced MR imaging

用于体内成像的磁共振（MR）是生物系统研究中的既定工具。 最近，可以使用先进的MR技术询问组织功能状态。 成像组织功能的主要挑战是了解细胞生理学和MR参数之间的复杂相互作用。 磁共振物理提供了一个机会，以满足这一挑战，设计新的成像技术和更好的模型，以提取生理相关的参数。 理解组织功能的一个中心问题与脉管系统有关-组织的血液供应。 动态对比增强MR成像研究造影剂的体内分布，从而获得表征脉管系统的参数。 血管通透性是研究血管改变性疾病和药物的一个重要参数。不幸的是，由于血流等混杂因素，使用当前MR采集技术和使用现有模型无法直接访问渗透性。 我们将开发一种技术，该技术依赖于两种药物，这两种药物从血管中泄漏的倾向差异很大。 这种双示踪剂MR技术将提供血管渗透性。 同样令人感兴趣的是，水扩散成像提供了关于微米尺度上的细胞结构的信息。 我们的初步研究结果，在治疗肿瘤的扩散系数的短暂下降，不能解释目前的理解坏死过程中的组织扩散的动力学。 我们将进一步研究扩散系数的时间变化，使用不同的肿瘤模型和药物探索我们观察的普遍性，并将我们的发现与免疫组织化学，全组织切片相关联。 我们将比较来自扩散加权图像的组织灌注与来自动态对比增强成像的灌注。 将使用MR衍生和组织学衍生参数的相关性进行对两种成像方法至关重要的验证。我们已经开发了可靠的方法，相关的MR参数的组织学。

Magnetic Resonance (MR) as used for in-vivo imaging is an established tool in the study of biological systems. More recently, the tissue functional status can be interrogated using advanced MR techniques. The major challenge in imaging tissue function is to understand the complex interplay between cellular physiology and MR parameters. MR physics provides an opportunity to meet this challenge by devising new imaging techniques and better models to extract physiologically relevant parameters. A central question in understanding tissue function relates to vasculature -- the blood supply of tissue. Dynamic contrast-enhanced MR imaging studies the in-vivo distribution of contrast agents and thus gives access to parameters characterising vasculature. One parameter with important implications for studies of vasculature-changing diseases and drugs is vessel permeability. Unfortunately, permeability is not directly accessible using current MR acquisition techniques and using existing models due to confounding factors like blood flow. We will develop a technique that relies on two agents that differ greatly in their propensity to leak from blood vessels. This dual-tracer MR technique will give access to vessel permeability. Also of great interest, water diffusion imaging provides information about cellular structure on a micrometer scale. Our preliminary findings of transient decreases of diffusion coefficients in treated tumours are not explained by the current understanding of the dynamics of tissue diffusion during necrosis. We will further investigate the temporal change of diffusion coefficients, probe the universality of our observation using different tumour models and drugs, and correlate our finding to immunohistochemical, whole-tissue sections. We will compare tissue perfusion derived from diffusion-weighted images with perfusion from dynamic contrast-enhanced imaging. The validation crucial for both imaging methods will be performed using correlation of MR-derived and histology-derived parameters. We have developed reliable methods of correlating MR parameters to histology.