A novel technique directed toward risk assessment of a patient's plaque vulnerability, wherein clinical events may be caused by internal plaque components affecting a lumen within an artery. A surface area projection or shadow of one or more plaque components onto a lumen can be measured and assessed. Optionally, a total volume projection onto the lumen can also be measured and assessed to refine the determination of risk to a patient and to monitor the progression of atherosclerosis over time.