A system and method for dual energy CT spectral imaging that provides for accurate blood vessel stenosis visualization and quantification is disclosed. The CT system includes an x-ray source configured to project x-rays toward a region-of-interest of a patient that includes a blood vessel in a stenosed condition and having a plaque material therein. The CT system also includes an x-ray detector to receive x-rays emitted by the x-ray source and attenuated by the region-of-interest, a data acquisition system (DAS) operably connected to the x-ray detector, and a computer programmed to obtain a first set of CT image data for the region-of-interest at a first chromatic energy level, obtain a second set of CT image data for the region-of-interest at a second chromatic energy level that is higher than the first chromatic energy level, and identify plaque material in the region-of-interest by analyzing the second set of CT image data.