The present invention is directed to a method and apparatus of scoring an arterial obstruction. The present invention includes identifying a particular group of pixels corresponding to a calcified region of coronary artery of a patient and based on the satisfaction of a number of thresholds connectivity criteria, determining a calcification score of that calcified region as indicative of the patient's risk of cardiovascular disease including atherosclerosis, heart attack, heart failure, and stroke. The present invention further includes determining the scaling factor unique to a particular imaging slice of data to provide a value of calcium weight and volume that is indicative of the true obstruction and true volume of the calcified region.