| Glioma is the most common type of brain tumor. Radiotherapy is one of the most important means to treat the glioma. Nowdays, all radiotherapy plans are based on CT images or CT fusion with MR SE sequence. However a lot of important structures or pathology of the central nervous system are unable to distinguish CT and MRI SE images. But new functional Magnetic Resonance Imaging(f MRI) technologys such as Diffusion Tensor Imaging(DTI) and Fiber Tractography(FT) can make the study of normal microstructure and pathological state for the nervous system come into a microscopic level.The study has solved three problems existed in the radiotherapy of glioma via using the f MRI and its information:1. Using Fractional Anisotropy(FA) and FA Ratio to identify the glioma cells’ invasion of the peripheral fiber. Compare the FA and FA ratio of high grade glioma(HGG), peripheral fiber of the high grade glioma, low grade glioma(LGG) and peripheral fiber of the low grade glioma. After analysis 4 HGG cases and 3 LGG cases results, it proved that FA is not useful to identify the invasion of glioma cells.2. Using Diffusion Weighted Imaging(DWI) and Apparent Diffusion Coefficient(ADC) assist contouring of the HGGs’ CTV. Compare with the conventional contouring of the CTV, using ADC and DWI information will reduce the volume of the CTV. That will change the strategy of the HGG radiotherapy.3. Use DTI and its information to contour the nervous nucleus as Organ at Risk(OAR). Subventricular zone(SVZ) and subgranular zone(SGZ) are considered as contain most of the Neural Stem Cells of adults. Reducing the dose to neural stem cell compartments can prevent the radiation-induced cognitive impairments. The study use FA and FT to assist contouring of SVZ and SGZ. The new OARs will change the strategy of the LGG radiotherapy to improve the quality of life.The paper summarizes the accomplished work of the f MRI in glioma radiotherapy, and predicts the future work for f MRI using in radiotherapy. |
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