It is believed that more than 80% of sudden heart attacks are caused by rupture of vulnerable plaques leading to the formation of blood clots and subsequent coronary stenosis and infarction. As opposed to a stable calcified plaque, the unstable plaque is atherosclerotic and consists of fatty lipids covered by a thin fibrous cap. By standard angiography it is possible to identify stenotic regions in the coronaries. Based upon the severity of the stenosis, the treatment is decided. This may be balloon angioplasty, stenting, or by-pass shunting. Angiography does not distinguish atherosclerotic vulnerable plaques from stable, and a decision to intervene which is based upon the degree of stenosis is not based upon a major issue, a vulnerable or a stable plaque. Many mildly stenotic vulnerable plaques will therefore be left untreated at a significant risk for the patient. Additional techniques which could distinguish between plaques of different kind is therefore of great interest. This is what is going to be investigated in this project.