My undergraduate research is in the Biomedical field dealing with fluid mechanics in the brain. The perivascular space (PVS) are small concentric spaces around blood vessels is hard to see with the ventricles. The MRI scans are viewed in three dimensions with segmentation programs such as MATLAB, ITK Snap, and ImageJ. The objective is to segment out the ventricles to pronounce images of PVS. To segment the ventricles, I am creating a 4D matrix in MATLAB of the MRI slices. Each slice is segmented using a freehand or flood fill tool to create a logical mask of where the ventricle is located on that slice of the brain. Inverting the logical matrix and multiplying it element wise with the original MRI brain creates a new mask. Using ITK Snap I segment out the ventricles in three dimensions from a thresholding and flood fill technique. I write a script in MATLAB to concatenate the 3D matrix from the MATLAB freehand to the ITK snap flood fill segmentation to create a 4D matrix showing the mask with the ventricles segmented out in red, green, or blue. The colors depend on if the ventricle was segmented with the freehand, flood fill, or both.