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分级有关，因此需要直接测量肿瘤的血管系统和细胞密度。动态敏感性对比磁共振成像（灌注磁共振成像）可以提供相对脑血容量，因此应该是评估肿瘤血管的可靠方法。我们的第一个目的是利用梯度回声平面成像技术评估最大相对脑血容量（rCBV）与胶质瘤的组织学和血管造影血管的关系。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比例与组织学和血管造影血管状况显著相关。胶质母细胞瘤的最大rCBV比值明显高于低级别胶质瘤。灌注磁共振成像对胶质瘤分级比常规磁共振成像更有用。由于复杂的肿瘤血管生成，肿瘤血管的大小变化非常大，而梯度回声平面成像技术非常适合这一目的。接下来，我们评估了扩散加权磁共振成像与回声平面成像技术在描绘肿瘤细胞和胶质瘤分级方面的效用。用个人电脑上的NIH成像软件分析肿瘤细胞，并与表观扩散系数（ADC）进行比较。最小ADC与肿瘤分级的关系也被评估。肿瘤细胞数与胶质瘤的最小ADC值有良好的相关性。高级别胶质瘤的最小ADC明显高于低级别胶质瘤。弥散加权磁共振成像是一种评估胶质瘤细胞结构和分级的有用技术。这些信息是常规磁共振成像无法获得的，对胶质瘤的诊断和表征是有用的。

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.