The Application Of BOLD-fMRI And Diffusion Tensor Imaging In Diseases Of Visual Pathways

The brain structure and the function relations have been the basic problems of the research for modern imaging technology, especially the development of the Neurosciences and Magnetic Resonance Imaging (MRI).People was not confined to research the pure autopsy and the animal studies,but more focus on through the non-invasive way to realizes the living specimen brain structure and the function research.Functional magnetic resonance imaging (fMRI) as a kind of special imaging technology,which is conform to this demand produces.This kinds of fMRI studies is based on the blood oxygenation level dependent (BOLD) (i.e. local area caused by brain activity in the blood concentration changes in deoxyhemoglobin Indirectly reflects the brain activity),it can comprehensive brain function,imageology and anatomical three aspects information of the human brain, achieve reach the each purpose function non-invasive positioning. Diffusion tensor imaging (DTI) are developed on diffusion weighted imaging (DWI),that basis on non-invasive observation living brain white matter fiber who′s macro and micro structure, and can through quantitative index response characteristics of white matter fiber bundles.In order to discuss the visual pathways lesions patient's brain white matter structure change and cortex function changes, the correlation among the assist clinical formulate operation program. We had analyzes 21 patients of different visual pathways lesions and 10 cases of normal volunteers BOLD - fMRI and DTI show, and in conjunction with the relevant references, hoping to great extent protection function and the structure of the whole sex, improve after the survival of patients who underwent the quality.Methods:We had collected 21 patients with visual pathways lesions for different properties, and 10 normal volunteers. They all underwent conventional MR imaging, BOLD-fMRI and DTI respectively. As for anatomic localization sagittal T1WI (t1-a MPR-ns-sag-p2-iso), TR: 1900ms, TE: 2.5 ms, the flip angle 9°. BOLD-fMRI adopts the GRE-EPI sequence, TR: 3000ms, TE: 30ms, the flip angle 90°, the corner scanning time 3min8s. The DTI adopts EPI sequence, 64 diffusion gradient direction, b 1000s/mm2, TR: 6315ms, TE: 93ms, NEX: 2. The BOLD-fMRI primitive image carries on processing after the spm5 software may observe the visual cerebral cortex to activate the area distributed situation and the activation volume (VOXELs), and calculates always activates the volume and the patient relative activation volume (rVOXELs, trouble side and healthy side vision cerebral cortex activates volume ratio). The anatomical image, BOLD-fMRI and DTI together the original image input Siemens workstation Neuro 3D software.The software automatically generated anatomical image, BOLD, DTI overlay maps and integration of visual cortex activation signal (in red and yellow warm color represents ) of the DEC map, ADC map. Uses"the seed sport"in the DEC map to reconstruct the optic radiation fibrous bundle,Which respectively lateral genieulate nucleus(LGN) and the visual cerebral cortex activates area as two positions.Then, observed the position relations between of the optic radiation , lesion and visual cortex activation area; And optic radiation fiber damage and visual cortex the distribution of inactive signal. In DEC map select the area of optic radiation relatively intact as areas of interest (ROI) measurement FA value, and then selected the corresponding position in the contralateral optic radiation. Each ROI was the diameter 3.0mm circle, altogether selected 4 group of ROI, this system might can also automatically the corresponding ADC values within the ROI;Calculates the double sidelong glance to emit ROI in the unit area the average FA value, the average ADC value and patient's relative FA value (rFA , trouble side and healthy side average FA value ratio).To the rFA and the rVOXELs data carries on the Pearson relevance analysis.Results:BOLD-fMRI performance: normal volunteer bilateral vision cerebral cortex obviously activates obviously,who performance for flake and symmetric distribution.Comparison the anatomy,BOLD and the DTI superposition map ,we can see activates many by the Brodmann17 area, the Brodmann18 next best, the Brodmann19 area are least; And the left and right both sides vision cerebral cortex activates the volume quite not to see the obvious difference (p>0.05). This experiment patient group eliminates the topping to move false shade big, enters the group 20 examples finally. Lesions of patients with different active region due to the location varied, but the overall distribution of active regions the same trend with the normal group. Patient group is less than the total volume of visual cortex activation normal group (p<0.05), and ipsilateral activation of the visual cortex total volume is less than the average healthy side (p<0.05). 1 case of pituitary adenoma patients with bilateral visual cortex activation volume than the normal group, the average activation volume decreased (p<0.05), but the left and right sides of the visual cortex have no significant difference in activation volume, and the activation area roughly symmetrical distribution. 1 cases of pituitary patients who′s right side of the optic chiasm was pressured significantly,and have no activation in the right visual cortex. 18 patients (2 patients occipital brain vascular malformations, occipital gliomas and metastatic tumors of the 7 cases, 1 case temporal-occipital and 1 case of tempora meningioma) patients the ipsilateral visual cortex activation volume was reduced or even disappear, the activation area distribution is more scattered.Activation of the contralateral visual cortex, area distribution loss of symmetry.And 3 patients (occipital gliomas 2 case, occipital metastatic tumors 1 case) and 3 patients (occipital gliomas 1 case, occipital metastatic tumors 2 case) were showed no visual cortex were activated on bilateral and unilateral separately.DTT performance: normal optic radiation fibers is given by the LGN of the green fanshaped fiber bundle, who had go back next to the posterior horn of lateral ventricle and ends at the active region under the occipital cortex. Form of bilateral optic radiation fibers symmetrical, form and structure complete well. One case of pituitary tumors patient was seen the bilateral optic radiation and optic chiasm fibers form and running well, only to see fiber optic chiasm were slightly sparse than contralateral; 1 case of pituitary tumor′s right half optic chiasm fiber was compression shift and most of the interruption.The right side optic radiation fibers sparse than contralateral, but the form and running well. 16 (occipital cerebral vascular malformations in 2 cases, occipital 7 cases of glioma and metastatic tumors separately) patients′the affected side compared with the contralateral optic radiation fibers was sparse ,structure is not complete and locally interrupted,discontinuous or even remote structure disappeared. Compressive residual fiber displacement, and can be seen in some patients taking the line of local fiber orientation change. 1 cases of meningioma can be seen compared with the contralateral optic radiation fibers sparse, the proximal optic radiation fibers affected by lesions in deformation, displacement, and to change the accumulation of fiber bundles;Another 1 case of meningioma patients is only part of the optic radiation fibers showed that the lesion effects were not change the direction of walk the line, and its shape can still be a slight displacement, fiber bundles sparse accumulation. These patients′anatomy,BOLD- fMRI and the DTI superposition map are visible residual fiber of optic radiation fibers penetrate the active region. Application of Pearson correlation analysis showed that the experimental visual pathway lesions in patients with optic radiation and visual cortex rVOXELs rFA value there is no correlation between (P> 0.05).DEC performance: normal radiation can be seen as the thin green strip of high signal, bilateral symmetry, form a complete and clear boundary . Optic radiation issued by the LGN, who running as the fan and convex outward . Optic radiation to the rear side by the posterior horn of lateral ventricle to terminate in the occipital visual cortex activation area. 2 cases of bilateral optic radiation in patients with pituitary tumors morphology and form like with the normal,slightly lower FA values, ADC values increased slightly; One of them was pressured with the right of optic chiasm, the right optic radiation slightly narrower than the opposite.16 (occipital cerebral vascular malformations in 2 cases, occipital 7 cases of glioma and metastatic tumors separately) patients′compared with the contralateral optic radiation narrowing of the affected side and the asymmetric shape of the lateral view of radiation, slightly lower FA values, ADC values increased slightly. Some patients the direction of optic radiation had changed, that showed blue-green color mixed. The boundary between the lesion and the optic radiation is not clear, the optic radiation structure disappeared within the lesion . The residual optic radiation had deformation and shifting. 2 cases of meningioma patients compared with the contralateral optic radiation narrowing of the affected ,slightly lower FA values, ADC values increased slightly side; The proximal of optic radiation had deformation and shifting, fiber bundles to change (the color to blue-based). These patients, DEC maps performence the end of radiation associated with different degrees of activation areas. The average FA value of the ipsilateral optic radiation significantly lower than the healthy side (p <0.001), mean ADC value was slightly higher than the healthy side, but no significant difference (p> 0.05); while the normal group, left and right sides The average FA value of the optic radiation, the average ADC values were no significant differences (p> 0.05). Application of Pearson correlation analysis showed that the experimental visual pathway lesions in patients with optic radiation rFA and visual cortex rVOXELs value there is no correlation between the r = 0.244, (P> 0.05).Conclusion:(1) The application BOLD-fMRI and DTI can be showen range of lesions and the location of the visual cortex activation relationship , and can be showen visualize the optic radiation and the different nature of the relationship between the visual pathway lesions and damage: including pushing and shoving, the displacement, some damaged and severely damaged other.That all can help develop protection to remove the tumor while minimizing the visual cortex of the surgery program.(2) DEC plans to provide more information and anisotropic dispersion fiber degree of change information, and enhance the FA value of the measurement region of interest location accuracy.(3) Their combination can be visualized as the area of radiation and visual cortex activation is connected .That is,the visual cortex and visual pathway functional integrity are closely related.