In-vivo imaging of cell migration using contrast enhanced MRI and SVM based post-processing

The migration of cells within a living organism can be observed with magnetic resonance imaging (MRI) in combination with iron oxide nanoparticles as an intracellular contrast agent. This method, however, suffers from low sensitivity and specificty. Here, we developed a quantitative non-invasive in-vivo cell localization method using contrast enhanced multiparametric MRI and support vector machines (SVM) based post-processing. Imaging phantoms consisting of agarose with compartments containing different concentrations of cancer cells labeled with iron oxide nanoparticles were used to train and evaluate the SVM for cell localization. From the magnitude and phase data acquired with a series of -weighted gradient-echo scans at different echo-times, we extracted features that are characteristic for the presence of superparamagnetic nanoparticles, in particular hyper- and hypointensities, relaxation rates, short-range phase perturbations, and perturbation dynamics. High detection quality was...活体内细胞的迁移行为，可通过结合以氧化铁纳米颗粒作为细胞内对比剂的磁共振成像（Magnetic Resonance Imaging，MRI）技术进行观测。然而该方法存在灵敏度与特异性不足的问题。为此，本研究开发了一种定量无创的活体细胞定位方法，该方法采用对比增强多参数磁共振成像技术，并结合基于支持向量机（Support Vector Machines，SVM）的后处理流程。本研究制备了以琼脂糖为基质、内部带有不同腔室的成像体模，各腔室中包含不同浓度的经氧化铁纳米颗粒标记的癌细胞，以此对用于细胞定位的支持向量机模型进行训练与评估。通过在不同回波时间下开展的一系列T2*加权梯度回波扫描所获取的幅值与相位数据，我们提取出可表征超顺磁纳米颗粒存在特征的多项特征参数，具体包括高信号与低信号、弛豫速率、短程相位扰动以及扰动动力学特性。本方法具备优异的检测质量……