Diffusion Tensor Imaging-based Fiber Tracking Of The Optic Radiation In Extracerebral Lesions

Background: The optic radiation can be infiltrated or damaged in brain lesions。Little is known about optic radiation injury in patients with extracerebral lesions besidethe optic radiation.Objective: Magnetic resonance diffusion tensor imaging can clearly detectextracerebral lesions beside the optic radiation. This study showed that alteredanisotropy values correspond with bilateral optic-radiation shape, size and location.Methods: Totally18preoperative-Meningioma and10postoperative-EpiduralHematoma patients completed the whole experiment. Three-dimensional radioactivetracing and conventional magnetic resonance imaging of optic-radiation fiber bundles in18meningioma patients before surgery using iPlan2.6software. Optic radiationinvolving tissues observed by magnetic resonance-diffusion tensor imaging usingDTI-Studio software. Optic radiation involving tissues and postoperative-EpiduralHematoma patients in10postoperative-epidural hematoma patients observed bymagnetic resonance-diffusion tensor imaging using DTI-Studio software.Results: The results of conventional MRI, FA, color-coded tensor maps andthree-dimensional white-matter tracing were compared.Patients were classified into fourintervals of the ratio of the FA value for the affected side to that for the healthy side.Patients in the first interval, having a ratio less than25%, had complete destruction ofthe optic radiation; patients in the second interval, having a ratio of25%–50%, hadmoderate damage; patients in the third interval, having a ratio of50%–75%, had ashifted optic radiation; and patients in the fourth interval, having a ratio greater than75%, had a normal or nearly normal optic radiation. In the group ofpreoperative-Meningioma patients, there was one case of complete destruction of theoptic radiation, with an FA value ratio of the affected side to the contralateral side of10.5%; three cases of shift and moderate destruction, with FA value ratios of46.3%, 40.5%and37.4%;11cases of slight shifting, with the FA value ratio having a mean of69.6%; and three normal or nearly normal cases, with an FA value ratio greater than75%.In the group of postoperative-Epidural Hematoma patients, there was2case ofcomplete destruction of the optic radiation; three cases of shift and moderate destruction;4cases of slight shifting; and one normal or nearly normal cases.Conclusion: Employing magnetic resonance diffusion tensor imaging,three-dimensional white-matter imaging and conventional magnetic resonance imagingcan demonstrate the extracerebral lesions and compression on surrounding brain tissue.A color-coded tensor map and three-dimensional tracer diagram were applied to clearlydisplay the optic-radiation location, course and damage. Results show that the alteredanisotropy values of extracerebral lesions patients correspond with optic-radiation shape,size and position on both sides. Experimental findings indicate that the magneticresonance diffusion tensor imaging technique is a means of tracing and clearlyvisualizing the optic radiation.