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Quantification of the living human visual system using MRI methods has

Quantification of the living human visual system using MRI methods has been challenging but several applications demand a reliable and time-efficient data acquisition protocol. with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high spatial resolution DTI protocol with FACT algorithm we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm optic tract optic radiations free of contamination from neighboring white matter tracts. quantification and visualization of human visual pathways at high spatial resolution on 3T in clinically acceptable scan time. We also showed the ability MPEP HCl to quantify the tract volume and corresponding diffusion tensor metrics of optic tract and optic radiations as well as distinguishing the optic radiations from your major neighboring pathways such as the ILF IFOF OPT and PTR. The middle longitudinal fasciculus is usually another association tract coursing above the ILF and connecting the temporal lobe with substandard parieto-occipital confluence (not shown) which was discussed in detail MPEP HCl elsewhere [61]. Distinguishing the adjacent connections of the occipital cortex is usually useful to unravel the neural network of complex visual functions. For example distinguishing MYT1 the OPT will be beneficial in the study of visuomotor coordination involving the occipito-ponto-cerebellar tracts [62]. Our DTI acquisition protocol applied high MPEP HCl spatial resolution and thinner slice thickness using higher magnetic field strength that resulted in reduction in both partial volume averaging in the voxel and magnetic field gradients. This provided higher and more detectable tensor anisotropy within deep gray matter nuclei such as the LGN [4. It allowed us to trace the optic MPEP HCl tract and optic radiation synapsing in the thalamus. The current MRI data were acquired using anisotropic voxel sizes (i.e. 2 x 2 x 1 mm interpolated in k-space to 1 1 x 1 x 1 mm). In our experience [48 61 22 the acquisition protocol and analysis strategy were adequate for tracing the fibers coursing along the direction of higher resolution (craniocaudally oriented fibers running along the thinner dimensions in the axial plane). This acquisition paradigm also resulted in less contamination from craniocaudally oriented crossing fibers within the voxel and less intravoxel inhomogeneity with resultant improved resolution and traceability of fibers running along other dimensions (for example the visual pathways coursing in the anterior-posterior direction). For example the current data also enabled the tracing of finer pretectal fibers (Fig. 3f) and the arching route of the Meyer’s loop (Figs. 3a) [7]. Using high-resolution 3D fiber tract reconstruction has several advantages over studying 2D ROIs. First unlike 2D ROI placement 3 DTT has a better ability to demonstrate the integrity of the fiber tracts by lesions [11 12 13 Second combining high spatial resolution and smaller slice thickness 3D tractography with cMRI data increases the validity of results obtained from 3D fiber reconstruction. Third by using multiple ROIs in different planes (sagittal and coronal) contamination and partial volume effects from adjacent tracts for example the PTR or OPT was avoided. We delineated the ORs from adjacent major fiber tracts such as the IFOF ILF OPT and PTR which have been a major source of confusion in the occipital lobe on prior DTI studies. Our quantitative analysis demonstrates a left-sided laterality of the FA values of the optic radiations. This has been reported in prior DTI studies and might be due to developmental asymmetry of the optic radiations the significance of which remains unclear. All 5 study subjects were right-handed young adult males. However dominant vision sidedness was not investigated in our MPEP HCl subjects which might have MPEP HCl a role in the laterality styles of the visual pathways. The number of subjects used in the current study is usually small to arrive at a more comprehensive quantitative assessment of the effects of side gender and age. Our results also demonstrate a marked difference in mean diffusivity between the optic tract and optic radiations (MD is usually markedly higher in optic tract ~ 1.25×10?3 mm2/sec compared to the optic radiation ~ 0.86 x10?3 mm2/sec). Since the MD values differ due to the level of.