1. Computer-implemented segmentation and quantification method using an intravascular optical coherence tomography (OCT) system having an OCT signal emitting and receiving instrument comprising: obtaining an OCT image set comprising one or more images of a portion of a blood vessel; segmenting a lumen portion of at least one of the one or more images; segmenting an OCT signal emitting and receiving instrument portion of the at least one of the one or more images; segmenting a vessel wall portion of the at least one of the one or more images; wherein the segmenting a vessel wall portion step comprises obtaining at least one texture mapping by processing at least one of the one or more images with at least one Gabor filter; and, determining a contour having maximum texture difference inside and outside the contour by applying active contour processing to the at least one texture mapping; obtaining an initial contour for the active contour processing from a boundary determined in the segmenting the lumen portion step; and segmenting a calcified plaque portion of the at least one of the one or more images.