Observation of Cholesterol Dissolved in Microscopic Deposits of Free   Fatty Acids in the Lumen of an Aorta of a Mouse Model for Human   Atherosclerosis
  The Raman spectrum of microscopic droplets of lipid material on the lumen of the aorta of an apolipoprotein E knock-out mouse were reported in the proceedings of an SPIE conference. Based on the absence of the carbonyl band in the spectrum, at that time it was determined that the spectrum represents free fatty acids rather than triglycerides. More recent examination of the spectrum indicates that these droplets contain dissolved cholesterol, and thus can be used as an early indicator of the atherosclerosis process in animal models during drug development. 
Fran Adar