Binary Lesion scans

Hi, I have been trying to work with the tissue segmented scans and want to have the scan as a binary map indicating the voxels belonging to the lesion load. I opened the scan on MATLAB and seem to have strange noise in the back ground.

Has anybody attempted to convert this scan into a binary map?

Could you provide links to or further details about where you sourced the segmented scans and what binary map refers to in this context? It will help me to direct your question to the right person. Thanks