The study of FA and ADC values by diffusion tensor imaging at 3.0T on malignant cerebral astrocytoma

Objective:To investigate the value of FA and ADC values of diffusion tensor MR imaging on malignant cerebral astrocytoma. Methods:14 patients with malignant cerebral astrocytoma proved by surgery and pathology underwent MRI plain and contrast-enhanced scanning,diffusion tensor MR imaging and 1H-MRS before operation. We defined tumor center as an area containing the highest choline/creatine and choline/N-actetyl aspartate ratios,contrast enhancement,and abnormal T2 signal intensity. Tumor border was defined as tissue with abnormal Cho/Cr and Cho/NAA ratios,no enhancement,and high T2 signal intensity. Peritumoral edema area was defined as tissue with normal MRS,no enhancement,and high T2 signal intensity. Normal white matter was assumed if tissue had normal proton MR spectra,no enhancement,and normal T2 signal intensity in the hemispheres ipsilateral or contralateral to tumor. FA and ADC maps were calculated and regions of interest were manually placed over areas of tumor center,tumor border,peritumoral edema,and normal tissue. The values of FA and ADC in 4 regions narrated above were measured as FA1-4 and ADC1-4,respectively. Comparisons were made by analysis of variance.Results:The average FA values of tumor center,tumor border,peritumoral edema,and normal white matter were FA1:0.1822±0.0583,FA2:0.2947±0.0786,FA3:0.1769±0.0942,FA4:0.6668±0.0817. There were significant differences between FA1-3 and FA4(P=0.000),and between FA2 and FA1,FA3 (P0.005),whereas there were no significant differences between FA1 and FA3(P0.05). The average ADC values of tumor center,tumor border,peritumoral edema,and normal white matter were ADC1:11.132±4.101,ADC2:11.175±2.983,ADC3:14.939±2.857,ADC4:7.265±0.914(10-3mm2/s). There were significant differences between ADC1-3 and ADC4(P0.005),and between ADC1,ADC2and ADC3(P0.005),while,there were no significant between ADC1 and ADC2(P0.05).Conclusion:The values of FA and ADC are helpful to detemine the bound of malignant cerebral astrocytoma.