| BackgroundThe structure of visual pathway is complex, an important function of the clinical disease, see more. With optic neuritis, atrophy of the optic nerve, optic nerve glioma, meningioma and surrounding the optic nerve lesion of optic nerve and optic chiasma related, related lesions extending to the suprasellar pituitary microadenoma, metastasis, and brain diseases affect the optic tract, optic radiation, the visual cortex can lead to visual impairment, serious impact on patientes quality of life. MRI images could more clearly display the visual pathway, especially the diffusion tensor imaging(DTI) and its three-dimensional structure like images, stereo display visual pathway and its relationship with the surrounding structures.ObjectiveTo explore the typical level of visual pathway and its typical level in the location, shape, adjacent relations and its law of change, measurement of optic nerve and optic chiasma diameter, angle, degree of agreement to study fault specimens with MRI imaging, diffusion tensor imaging(DTI) the position relation of visual pathway white matter fiber go the line and its adjacent structures, and provide the morphological evidence for the diagnosis and treatment of visual pathway lesions.Materials and methodSelected formalin fixed adult cadaveric head in 20 cases, including 15 cases of male, female 5 cases, respectively by the canthomeatal line, external door canthomeatal line, perpendicular to the midsagittal plane making head, coronary, sagittal transection specimen for the baseline.The collection of Anyang People’s Hospital room MRI, during the 2012 August to 2014 July, implementation head MRI scan of adults(≥20 years older,≤50 years older),100 cases had no clinical visual function abnormal examination, there were 50 males,50 females, aged 20-50 years old. The original image data input GE AW 4.2 workstation for image post-processing by Volume-one 1.72 software, to obtain MRI T2 weighted imaging, diffusion tensor imaging(DTI) of the directionally encoded color(DEC), take the computer automatic tracking of fiber bundles, obtain three-dimensional conformational map of white matter tracts.Results1. In the coronal sectional specimen and MRI images, the visual pathway of the optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiation and visual cortex can clearly identify, coronary tomography can clearly show the visual pathway and the adjacent relationship, and from the front to the rear of the continuous tracking observation. The orbital cavity section of optic nerve, optic canal segment and the optic chiasm mostly symmetrical distribution, there were no significant differences between the left and right side, men and women and the MRI image and sectional specimens(P>0.05). The optic nerve of orbital cavity section of the MRI image and sectional specimen of the long diameter, short diameter were (3.59±0.51) mm, (2.51±0.33) mm and (3.64±0.42) mm, (2.58±0.39) mm, optic canal segment of the MRI image and sectional specimen length to diameter, the shortest diameter were (3.48±0.41) mm, (2.50±0.33) mm and (3.50±0.47) mm, (2.44±0.39)mm, optic chiasma MRI image and sectional specimen of the long diameter, short diameter were (13.41±2.75) mm, (3.58±0.41) mm and (13.50±2.99), mm (3.51±0.49) mm.2. In the transverse sectional anatomy and MRI image, the visual pathway of the optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiation and visual cortex can clearly identify, cross-sectional can display before and after the visual pathway and around the adjacent relationship, and bottom-up continuous tracking observation, especially in the optic chiasm to the center of the upper and lower levels, can the optic nerve, optic chiasm and optic tract and other visual pathway structure at the same time display on one level, is to show the typical level of visual pathway. Left and right optic nerve and optic beam angle between the multiple symmetrical distribution, the optic chiasm and bilateral optic nerve, bilateral optic bundles, optic nerve and optic tract of the left and right side, the angle between the male and female sex and MRI image and sectional specimen showed no significant difference(P> 0.05). The optic chiasm MRI image and sectional specimens in transverse diameter, anteroposterior diameter were (13.48±2.31) mm, (7.68±1.83) mm and (13.54±3.12) mm, (7.81±1.29) mm, bilateral optic nerve, bilateral optic bundles, optic nerve and optic tract between the MRI image and sectional specimen clamping angle were (65.85±5.31)°, (111.52±10.34)°, (71.11±6.93)° and (66.91±6.10)°, (110.83±9.92)°,(71.43±6.15)°.3. In the sagittal sectional specimen and MRI images, the visual pathway of the optic nerve, optic chiasm, optic tract, lateral geniculate nucleus, optic radiation and visual cortex can clearly identify, sagittal can display before and after the visual pathway and on adjacent relationship, and since the median sagittal continued to both sides of track. The optic chiasm in men and women, and the MRI image and sectional specimens showed no significant difference(P>0.05). The optic chiasm MRI image and sectional specimens of the upper and lower diameter and anteroposterior diameter were (3.58±0.41) mm, (7.68±1.83) mm and (3.51±0.49) mm, (7.81±1.29) mm.4. The optic nerve in fractional anisotropy(FA) images showed high signal, in the directionally encoded color(DEC) images because of nerves is fore-and-aft direction is green, the optic chiasm in the directionally encoded color(DEC) images were small pieces of red signal was visible, the optic tract in the fractional anisotropy(FA) images showed high signal, in the directionally encoded color(DEC) images showed a red or green, optic radiation in fractional anisotropy(FA) images showed high signal, in the directionally encoded color(DEC) images showed high signal on the green uniform. Forward looking road fiber bundle like structure chart was "X" shape, the rear view road optic radiation is green, can be divided into 3 beams. The fractional anisotropy(FA) values were higher, up to more than 0.50, the highest close to the optic nerve, optic nerve,0.60, left and right side and the men and women of the optic tract, optic radiation degree of fractional anisotropy(FA) values and mean diffusivity(MD) values were not significantly different(P>0.05). The optic nerve, optic tract, optic radiation fractional anisotropy(FA) values and mean diffusivity(MD) values were (0.595±0.067)×10-3s/mm2, (0.531±0.062) X 10-3s/mm2, (0.509±0.029)× 10-3s/mm2 and (0.948±0.112)×10-3s/mm2, (0.944±0.131)×10-3s/mm2, (0.763±0.050)×10-3s/mm2.Conclusion1. Sectional specimens and MRI image of visual pathway is highly consistent, MRI imaging is a reliable method for diagnosis of pathological changes of visual pathway.2. Optic nerve section and orbital cavity tube section of the long and short diameter measurement, is helpful to the diagnosis of atrophy of the optic nerve and optic neuritis, measuring chiasma diameter and bilateral optic nerve, bilateral optic tract, optic nerve and optic tract between angle, contribute to the lesions of sellar region compression of the optic chiasm causes the angle of the change of imaging diagnosis.3. Diffusion tensor imaging(DTI) can better display of white matter tracts of visual pathway, accurate understanding of brain white matter fiber anisotropy and water diffusion characteristics, provides a new technical method for clinical diagnosis of brain white matter fiber bundle lesions. |
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