The Appliance Of DTI In Intracranial Tumors And The Correlation Between FA And Microarchitecture

Objective: To study the difference in DTI parameters among intracranial tumors including meningioma, glioma, metastatic tumor, and schwannoma and the value of diagnosis and differential diagnosis. To analyze the characteristics of microarchitecture in different tumors and the correlation between FA and tumor microarchitecture.Methods:1. Diffusion tensor imaging: Eighty patients with intracranial tumor ( 34 meningiomas, 24 gliomas, 12 schwannomas, and 10 metastatic tumors) were performed axial diffusion tensor imaging by GE Signa Excite Ⅱ 3.0T MR scanner. The eight-channel head coil and SE EPI sequence were collected. The thickness was 5mm with no gap and 26 slices were selected. The data of every slice were collected in twenty-five non collinear directions. B values were 0 s/mm~2 and 1000 s/mm~2. TR and TE were 6000ms and minimum respectively. FOV was 240× 240mm~2, and image matrix was 128×128, and NEX was 2. The total scanning time was 2 minutes and 48 seconds. In the host computer, postprocessing were undertook in the original data using DTI private facilities of functool 3.0. First of all, the original data were corrected by a certain procedure to reduce image artifact and distortion. Then the threshold including the brain tissue and excluding the noise was set. After having the FA, VRA, EA, ADC, and II images done, ROIs in the parenchyma and necrosis within the tumor and peritumoral edema were selected. And then the parameter values were recorded for quantitative analysis.2. Immunohistochemistry method: The paraffin sections of these tumors were stained with VEGF and CD34 using immunohistochemistry method. PBS, replacing VEGF or MVD, was used in the negative control group. Hematoxylin was used to afterstain nucleus. The VEGF, MVD, celluar density, and relative cell diameter of every slides were recorded.3. Statistical method: SPSS 11.0 statistical package was used, and one-Way ANOVA was selected to analyze the difference among the tumors and Pearson correlation analysis to the correlation between FA and VEGF, MVD, tumorous cellular density and relative cell diameter.Results:1. DTI difference among different tumors:1.1 DTI difference in tumor parenchyma: FA and VRA in meningioma ? is obviously higher than glioma and metastatic tumor, and glioma is significantly higher than metastatic tumor. VRA in meningioma is also obviously higher than schwannoma. EA in meningioma is significantly higher than glioma and schwannoma. ADC in glioma and schwannoma are statistically higher than meningioma.1.2 DTI difference in the region of tumor necrosisADC in the necrosis of meningioma is obviously lower than glioma and metastatic tumor.1.3 DTI difference in the peritumoral edemaFA, VRA, and EA in the peritumoral edema of meningioma is statistically higher than glioma. EA in the peritumoral edema of meningioma, glioma, and metastatic tumor is obviously higher than schwannoma. ADC in the peritumoral edema of schwannoma is significantly higher than glioma, metastatic tumor and meningioma.ADC in glioma is significantly higher than meningioma. Aside from these, II in the peritumoral edema appears different among different tumors, that is, schwannoma is lower than meningioma, glioma and metastatic tumor.2. Cellular density and the proportion of VEGF positive expression and have no significant difference among the four intracranial tumors. MVD in glioma is obviously higher schwannoma and meningioma, and metastatic tumor is obviously higher than meningioma. The relative cell diameter in glioma and metastatic tumor is significantly bigger than meningioma. The relative cell diameter in metastatic tumor is obviously bigger than schwannoma. The proportion of VEGF positive express,MVD, and cellular density have the tendency to increase according to the increased grade in gliomas, and the difference is significant.3. From the Pearson correlation analytic results, FA has positive correlation to VEGF, MVD, and cell density (R=0.768, P=0.002; R=0.868, P=0.000; R=0.825, P=0.000) in gliomas with different grade and FA has negative correlation to relative cell diameter in intracranial tumors(R=0.676, /*=0.008).Conclusion: There is difference among different intracranial tumors in DTI. FA has significant correlation to VEGF, MVD, cell density, and relative cell diameter. As a new imaging method, DTI can reveal the microarchitecture in the tumor and provide valuable information for intracranial tumor diagnosis and differention.