Value of Dynamic Susceptibility Contrast Magnetic Resonance Imaging and Diffusion-weighted MR Imaging in the Evaluation of Brain Tumors

肿瘤的恶性程度通常与肿瘤的分级有关，需要直接测量肿瘤的血管和细胞密度。动态磁化率对比磁共振成像(MR灌注成像)能提供相对脑血容量，是评价体内肿瘤血管形成的可靠方法。我们的第一个目的是用梯度回波平面成像技术评价脑胶质瘤的最大相对脑血容量(RCBV)比值与组织学血管和血管造影的关系。我们还评估了rCBV图对胶质瘤分级的有效性。胶质瘤的最大rCBV比值与组织学和血管造影的血管显着相关。胶质母细胞瘤的最大rCBV比值显著高于低级别胶质瘤。磁共振灌注成像对胶质瘤的分级比常规磁共振成像更有价值。由于复杂的肿瘤血管生成，肿瘤血管的大小非常不同，梯度回波平面成像技术非常适合于这一目的。其次，评价磁共振弥散加权成像结合回声平面成像技术在显示肿瘤细胞密度和胶质瘤分级中的作用。用个人计算机上的NIH成像软件分析肿瘤细胞密度，并与表观扩散系数(ADC)进行比较。并评价最小ADC值与肿瘤分级的关系。肿瘤细胞密度与胶质瘤的最小ADC值有很好的相关性。高级别胶质瘤的最小ADC值明显高于低级别胶质瘤。磁共振弥散加权成像是评估肿瘤细胞密度和胶质瘤分级的有用技术。这些信息是常规磁共振成像所不能获得的，对胶质瘤的诊断和定性有帮助。

The degree of tumor malignancy generally correlates to tumor grade, and the direct measurement of tumor vasculature as well as cellular density is desired. Dynamic susceptibility contrast magnetic resonance imaging (perfusion MR imaging) can provide relative cerebral blood volume and, therefore, should be reliable methods to evaluate tumor vasculature in vivo. Our first purpose was to evaluate the relationship between the ratio of maximum relative cerebral blood volume (rCBV) and histologic and angiographic vascularities of gliomas using the gradient-echo echo-planar imaging technique. We also evaluated the usefulness of rCBV maps for grading gliomas. The maximum rCBV rations of the gliomas significantly correlated with both histologic and angiographic vascularities. The maximum rCBV ratios of the glioblastomas were significantly higher than those of low-grade gliomas. Perfusion MR imaging was more useful for grading glioma than conventional magnetic resonance imaging. Tumor vessel size is extremely variable due to complex tumor angiogenesis, and the gradient-echo echo-planar imaging technique was well suited for this purpose. Next, the utility of diffusion-weighted MR imaging with echo-planar imaging technique in depicting the tumor cellularity and grading of gliomas was evaluated. Tumor cellularity, analyzed with NIH imaging software on a personal computer, was compared with the apparent diffusion coefficient (ADC). The relationship of the minimum ADC to the tumor grade was also evaluated. Tumor cellularity correlated well with the minimum ADC value of the gliomas. The minimum ADC of the high-grade gliomas was significantly higher than that of the low-grade gliomas. Diffusion-weighted MR imaging was a useful technique for assessing the tumor cellularity and grading of gliomas. These informations were not obtained with conventional magnetic resonance imaging and were useful for the diagnosis and characterization of gliomas.