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Image Analysis Service
Diffusion tensor imaging data processing
This service performs diffusion tensor calculation and includes:
• Image co-registration and gradient table recalibration
• Image quality check and reporting
• Tensor calculation and generation of the following maps;
• Eigenvalues (parallel and perpendicular diffusivity)
• Trace (apparent diffusion constant (ADC) or mean diffusivity (MD))
• Westines linear (CL) and planar (CP) indices
• Color-coded orientation maps for three eigenvectores
Image pre-processing for multi-modal analysis
This pre-processing is necessary for subsequent detailed quantitative analyses.
• Image orientations, brain locations, and orientations will be all adjusted to the MNI template (ICBM152) or one of the contrasts within the same data by rigid alignment.
• The skull will be removed by one of the automated methods. Please note that automated skull removal often leaves dura attached to the brain. We recommend manual touch-up if precise cortical measurements such as cortical thickness measurements will be subsequently performed.
Whole-brain normalization-based image analyses I
We transform images to our brain atlas (JHU-DTI-MNI-ss) (lbam.med.jhmi.edu) using an advanced non-linear technique. The brain is automatically segmented to 118 anatomical regions. Size and various MR parameters such as FA, T2, MTR, and trace are reported as a list for each segmented structure. The shape-normalized images are ready for pixel-by-pixel statistical analyses.
Whole-brain normalization-based image analyses II
After whole brain normalization-based analysis, in which white matter is segmented to 118 structures, the brain is further segmented to 176 structures. This includes the cortex and associated peripheral white matter areas.
ROI-based detailed regional shape analysis
This analysis offers the sophisticated shape analysis of a single brain structure hand-segmented from each subject. Examples include the hippocampus of AD patients and the caudate of HD patients, in which we have a priori hypothesis about targeted brain areas.