Objective To determine whether the different pathological types of astrocytic tumours can be differentiated by diffusion tensor MR imaging. Methods In this study, diffusion tensor MR imaging was performed preoperatively in 67 patients with different pathological types of astrocytic tumours. Furthermore , T1WI, T2WI, FLAIR and T1WI enhancement scanning by GD-DTPA were performed preoperatively in all patients. The Mean diffusivity (ADC) values in the tumor parenchyma and normal white matter from different pathological types of astrocytic tumours were measured and analyzed. The ADC with the tumor parenchyma and normal white matter from the tumours were statistically analyzed by SPSS 19.0. The results were expressed as ± s and P < 0.05 was regarded as statistically significant differences. Results There were many differences with ADC (< 10-9 mm2/s) in the tumor parenchyma between fibrillary astrocytoma (1.48 ± 0.12、0.72 ± 0.05) from fat cell astrocytoma (1.31 ± 0.07, 0.69 ± 0.03), There were also many differences with ADC ( < 10-9 mm2/s) in the tumor parenchyma between fibrillary and fat cell astrocytoma from anaplastic astrocytoma (1.06 ± 0.11, 0.71 ± 0.04) and giant cell glioblastoma (0.98 ± 0.09, 0.73 ± 0.04). There were not differences with ADC in the tumor parenchyma between anaplastic astrocytoma from giant cell gliobastona. Conclusion Measurement of tumor parenchyma′s ADC values can identify different pathological types of astrocytic tumours , but not between anaplastic astrocytoma and giant cell glioblastoma. DTI is essential to preoperative evalution of astrocytic tumours.

Objective To investigate the value of intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) based on ISHIM sequence in the grading of astrocytic tumor.Methods We collected excised tumors confirmed by histological diagnosis from 42 patients including high-grade astrocytic tumors (10 WHO grade Ⅲ,18 WHO grade Ⅳ),and 14 low-grade astrocytic tumors (1 WHO grade Ⅰ and 13 WHO grade Ⅱ).All patients underwent conventional MR imaging,ISHIM IVIM-DWI,and contrast-enhanced MR imaging.Parameters of tumor parenchyma region,peripheral edema regions and the contralateral normal brain white matter sites were measured,and the statistical analysis was conducted.Results The D value in tumor parenchyma region was significantly lower,but the D* and f values were higher in high-grade astrocytic tumor when compared with lowgrade one and all had statistical significance;in tumor peripheral edema region,D value was lower in high-grade astrocytic tumor than that in low-grade one,and the difference had statistical significance but there was no significant difference in terms of the D* and f values.There was no significant difference of the D,D* and f values in contralateral normal brain white matter sites in both high-and low-grade astrocytic tumor.Conclusion The D,D* and f values measured by ISHIM IVIM-DWI are helpful to the judgment of tumor grade and it has greatapplication value in the differential diagnosis of high-and low-grade astrocytic tumor.

Objective To investigate the value of magnetic resonance (MR)diffusion kurtosis imaging (DKI)in diagnostic classi-fication of astrocytic tumors.Methods 31 patients with astrocytic tumors confirmed by operation and pathology were collected,in-cluding low-grade tumors (WHO gradeⅠ and Ⅱ)in 14 and high-grade ones (WHO grade Ⅲ and Ⅳ)in 1 7.Routine MRI and DKI scan were preoperatively conducted using Siemens 3.0T MR scanner.Mean kurtosis (MK),radial kurtosis (RK)and axial kurtosis (AK)values were calculated in the solid portion of the tumors and the contralateral normal white matter.Results The MK,RK and AK values in tumors were lower than those in contralateral normal white matter,and were significantly higher in high-grade tumors than those in low-grade ones (P <0.05).Conclusion The MK,RK and AK values obtained by DKI reflect the histological structure changes of the astrocytic tumors.DKI is helpful for the diagnostic classification of astrocytic tumors,exhibiting more value in optimi-zing the treatment.