The Clinical Research Of Evaluating The Pathological Grading Of Supratentorial Gliomas With Diffusion MRI

Objective: Gliomas originated from the neuroepithelial cells,they were the most common primary tumours in the nervous system.Gliomas had been reported to represent 40% of the whole intracal tumours,as well as most of them were malignant tumours.Gliomas often grew aggressively,they invaded into the local brain tissues.It was difficult to distinguish the boundaries of normal brain tissues accurately,as a consequence,radical surgical treatment of the gliomas weres difficult.Therefore the postoperative recurrence rate was extremely high.The main treatment of gliomas included surgery,radiotherapy and chemotherapy,but the prognosis of patients with gliomas was still poor.Many studies indicated that there was a close relationship between the pathological classification and its prognosis of patients with gliomas.The prognosis of patients with cerebral low-grade glioma was significantly better than them with the high-grade glioma.It was of great significance to improving the prognosis of patients that it assessed accurately the grading of glioma pathology before surgery.Because of it was able to optimize the operative and comprehensive treatment protocols.The inspection methods of gliomas relied mainly on imaging technology.Among them,magnetic resonance imaging was the most commonly used.In recent years,with the progress of magnetic resonance technology,especially the emergence of diffusion MRI,which gave us the new opportunities that it assessed accurately the grading of glioma pathology preoperatively.The issue mainly aimed to study the diffusion MRI technology,such as diffusion weighter imaging?DWI?and diffusion tensor imaging?DTI?.The topic was to explore the clinical value of preoperative pathological grading with the respective parameters of DWI and DTI,such as apparent diffusion coefficient?ADC?,fractional anisotropy?FA?,the relative ADC?rADC?,therelative FA?rFA?.ADC values,rADC values,FA values and rFA values were measured and compared in each groups and different regions.To compare the state of fiber bundle between low-grade group and high-grade group using diffusion tensor tractography?DTT?.Which was able to provide a possible new approach to accurately assess the pathological grading of gliomas.Methods: Objects of study were 32 patients of supratentorial gliomas who had been examined with conventional MRI and DWI,DTI,as well as undergone surgery from November 2014 to January 2016 at Tangshan Worker Hospital,HeBei Medical University.15 patients were female and 17 were male,with a mean age of 46.87±11.57?range 25 to 69 years?.All cases were primary,and they did not receive any treatment prior to admission.All patients in the study had been examined with conventional MRI and DWI,DTI,as well as undergone surgery.According to The 2007 WHO Classification of Tumours of the Central Nervous System,the pathological degree was determined by two pathologists with high qualification.The pathological degree of gliomas were divided into grade ? to grade ?.There were grade ? and grade ? in the low-grade gliomas,they were benign.There were grade ? and grade ? in the high-grade gliomas,they were malignant.The research objects were divided into low-grade group and high-grade group,grade ? and grade ? in the low-grade group and grade ? and grade ? in the high-grade group.ADC images,FA images and 3D fiber tracking images were reconstructed.To determine the tumour solid portion area and peritumoral edema area,contrasting T₂WI,enhanced T₁WI and Flair.ROIs were put in the tumour solid portion,peritumoral edema and in contralateral normal tissue.ADC values and FA values were measured in 3 regions: tumour solid portion,peritumoral edema and contralateral normal tissue.The ADC and FA value of the ROIs were recorded.To avoid errors,repeated each ROI measure 3 times and took the average.To calculate the rADC and the rFA,the rADC was the ratio of ADC value in tumour lesion area and in contralateral normal tissue,the rFA was the ratio of FA value in tumour lesion area and in contralateral normal tissue.To collect the parameter values for the next step data statistical processing and analysis.The data described with standard ± deviation.The data statistical analysis was performed by SPSS21.0 statistical software.To compare the ADC and FA value of the same grade group between in the tumour lesion area and in contralateral normal tissue using paired samples t test.The compairing of ADC,rADC,FA and rFA between low-grade group and high-grade group with independent sample t test.The AUC of ROC curve analysis was to evaluate the diagnostic value and accuracy of ADC and FA for glioma pathologic grading.To analyse the cutoff values of ADC and FA with ROC curve.The cutoff values for ADC and FA in differentiating low-grade group from high-grade group gliomas provided the best combination of sensitivity and specificity.To compare the state of fiber bundle between low-grade group and high-grade group with rank sum test.The inspection level of this study are 0.05.Results: 1 According to The 2007 WHO Classification of Tumours of the Central Nervous System and the postoperative pathological diagnosis report,32 cases of patients with glioma were divided into low-grade group of 12 cases and high-grade group of 20 cases;2 ADC in the same grade group comparing between the value in tumour solid portion,peritumoral edema and the one in contralateral normal tissue,differences were statistical significance,P < 0.05;3 ADC comparing between low-grade and high-grade in tumour solid portion,t=-5.603,P=0.000;ADC comparing between low-grade and high-grade in peritumoral edema,t=-5.073,P=0.000;rADC comparing between low-grade and high-grade in tumour solid portion,t=-2.143,P =0.040;rADC comparing between low-grade and high-grade in peritumoral edema,t=-2.714,P =0.011;differences were statistical significance;4 FA in the same grade group comparing between the value in tumour solid portion,peritumoral edema and the one in contralateral normal tissue,differences were statistical significance,P < 0.05;5 FA comparing between low-grade and high-grade t=-2.360,P =0.025;rFA comparing between low-grade and high-grade in tum--our solid portion,t=0.030,P =0.976;differences was not statistically ficant,P> 0.05;6 FA comparing between low-grade and high-grade in peritumoral edema,t=-2.360,P =0.025;rFA comparing between low-grade and high-grade in peritumoral edema,t=-3.533,P=0.001;differences were statistical significance,P < 0.05;7 The analysis by the ROC curve come to the conclusion that ADC value had better diagnostic value for glioma pathologic grading than FA value.The AUC of ADC value in tumour solid portion and in peritumoral edema were 0.933 and 0.885.The AUC of FA value in peritumoral edema was 0.729;8 DTT was able to show clearly the destructive degree of cerebral white matter fiber bundle.Of 12 patients in the low-grade group,cases were 7 displaced,4 Infiltrated,1 destroyed.Of 20 patients in the high-grade group,cases were 3 displaced,12 Infiltrated,5 destroyed.According to statistic analysis,the state of fiber bundle surrounding the tumour comparing between low-grade and high-grade,Z=-2.380,P=0.017,differences were statistical significance.Conclusion:1 As the parameters of MR diffusion imaging technology,ADC values and FA values could help assess the different pathological grading of supratentorial gliomas.And it come to the conclusion that ADC value had better diagnostic value for glioma pathologic grading than FA value2 The analysis by the ROC curve also come to the conclusion that ADC value had better diagnostic value for glioma pathologic grading than FA value.3 DTT was able to show clearly the destructive degree of cerebral white matter fiber bundle and display intuitively the relationship between tumour tissue and surrounding main white matter fiber tracts.