Application Study Of Diffusion Tensor Imaging In Both Normal Optic Radiation And Abnormal Optic Radiation Induced By Intracranial Neoplasms

PartⅠStudy of normal adult optic radiation by using MR diffusion tensor imagingPurpose: To investigate anisotropy of optic radiation, and elucidate changes of optic radiation during normal aging. Material and methods: 60 healthy adult volunteers (29 men, 31 women; age range, 24-66 years; mean age 42.8years) were studied using MR diffusion tensor. The FA values and MD values were measured. Results: The left side and right side of FA values of normal adult optic radiation were 0.517±0.023, 0.514±0.021 respectively; the left side and right side of MD values of normal adult optic radiation were (0.743±0.024)×10-3mm2/s, (0.740±0.025)×10-3 mm2/s respectively. There was no significant difference in FA or MD between the left and right hemisphere. FA trended to decline in optic radiation, but without significant relation. A significant MD increase with advancing age was observed in optic radiation (p=0.029). Conclusion: FA value can be used to quantitate anisotropy of optic radiation. There was a tenuous FA value reduction and MD value increase with increasing age.PartⅡApplication study of diffusion tensor imaging in abnormal optic radiation induced by intracranial neoplasmsPurpose: To evaluate the usefulness of diffusion tensor imaging in abnormal optic radiation in relation to intracranial neoplasms. Material and methods: To study 33 patients (18 men, 15 women; age range, 35-81 years; mean age 54.1 years) using diffusion tensor imaging. FA, DEC and DTT maps were obtained in all 33 patients to observe abnormality of optic radiation. FA values and MD values were measured in the regions of both abnormal radiation and contralateral radiation. Results: Abnormality of optic radiation was classified into four types: disruption+infiltration (18 cases), disruption+displacement (5 cases), infiltration+displacement (4 cases), displacement (6 cases). The FA values of optic radiation in peritumor edema regions were significantly lower than those in contralateral regions. The MD values of optic radiation in peritumor edema regions were significantly higher than those in contralateral regions. The FA values of optic radiation with peritumor edema regions in metastasis group were significantly lower than those in meningioma group. The MD values of optic radiation with peritumor edema regions in metastasis group were significantly higher than those in both glioma group and meningioma group. Conclusion: (1) Diffusion tensor imaging showed the abnormality of optic radiation. Diffusion tensor tractography allowed for visualization of optic radiation three dimensionally and was found to be beneficial in the surgical planning or prognosticating the prognosis of patient. (2) FA and MD can analyse quantitatively diffusion of optic radiation involved by the tumors.