| Purpose To investigate the diagnostic value of magnetic resonance T1-weighted DCE-PWI in predicting the pathological grade of glioma in the preoperative setting, and its relationship with tumor grade and vascular endothelial growth factor expression.Method 22 patients with glioma and 2 normal persons were investigated. Patients were aged 13-74 years, average 30.0 years, 14 cases were male and 8 were females. According to WHO criteria in 2000 for postoperative pathological classification of gliomas, three cases were of gradeâ… , 7 cases gradeâ…¡, 7 cases gradeâ…¢, 5 cases gradeâ…£. One of the lesions was infratentorial while the others were supratentorial. Conventional MR examination was first carried out in all patients, followed by DCE-PWI scan, and then routine enhancement scan. DCE-PWI scanning was done using a standard head coil with Turbo-FLASH sequence with the following parameters: TR / TE 199/1.05ms; TI 100ms; slice thickness 6mm; slice distance 1.2mm; flip angle 200; matrix 128×96; FOV 260×210. The intermediate level was selected as the largest level of glioma, and the time resolution was 4 seconds, a total of 90 time phases were scanned with an imaging time of 360 seconds. Gd-DTPA was injected from an antecubital vein with a dose of 0.4 ml/kg, using a high-pressure injection pump, at a rate of 4 ml/s. Contrast was injected during the sixth phase followed by administration of the same volume of normal saline to flush the catheter. Data was analyzed using Tofts and Kermode two-compartment pharmacokinetic model and the NORDICIC software to build Ktrans,Kep and Ve maps. Then, with T1 enhanced images as reference, the areas of greatest value of Ktrans in the tumor were chosen as regions of interest to calculate the average of the three parameters. Patients were operated within two weeks of the exam. VEGF immunohistochemical analysis was carried out after obtaining tumor samples using two-step method. One case of high-grade glioma was examined under electron microscope.Result The results showed that the permeability parameter Ktrans values of normal brain tissue was lower than glioma patients, about one tenth that of gradeâ… gliomas. Ktrans, Kep and Ve of gradeâ…¢-â…£gliomas were significantly higher than those of gradeâ… -â…¡. Ktrans and Kep of high-grade gliomas were increased four times more than in low-grade ones. Ktrans values were different between gradesâ…¡andâ…¢, but there was no difference between gradesâ… andâ…¡, and between gradesâ…¢andâ…£. Correlation of Ktrans, Kep and Ve with tumor grade was analyzed using spearman rank correlation. Correlation coefficient of Ktrans was greater (r=0.770, p<0.001) showing Ktrans values was positively correlated with tumor grade with a close relationship. In differentiating between low-grade and high-grade tumors the most appropriate Ktrans critical point ( threshold value) was 0.85 with specificity = 0.90 and sensitivity = 0.92. Using spearman rank correlation analysis of VEGF expression and Ktrans values, r = 0.551 (p = 0.008). Immunohistochemical analysis showed that VEGF expression in gradesâ… andâ…¡were mainly negative, in gradeâ…¢there was a positive rate of 85.72%, in gradeâ…£positive rate was 100%. Rank sum test gaveχ2 of 12.647 (p = 0.005). With spearman rank correlation analysis, r = 0.706 (p <0.001). Electronmicroscopy showed that in high grade glioma there was an increase in theextracellular space of endothelial cells, with a disrupted basementmembrane.Conclusion T1WI DCE-PWI is a good non-invasive quantitativemethod of analysis of microvascular permeability of glioma, especially the permeability parameter Ktrans value being closely related to the pathological grade of glioma. It can be used for the quantitative evaluation of microangiogenesis in glioma and provide a new reference for the degree of glioma malignancy. The threshold value for the differentiation between high- and low-grade glioma was 0.85 (specificity = 0.90, sensitivity = 0.92). There was a positive correlation between VEGF expression and Ktrans value.
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