Recent advances for OCT imaging of vascular tissue

A feasibility for OCT in the identification of vulnerable plaque. tile plaques which lead to most heart attacks, has been previously demonstrated (Circulation 93,1206-1213, 1996, Heart 77:397-404, 1997, Heart 82:128-133, 1999). However, poor imaging through blood remains the most significant disadvantage for OCT for vascular imaging. Since blood scatters primarily due to a mismatch in the refractive index between the cytoplasm and the serum, the refractive index of the serum was raised to increase the transparency of blood. Dextran and IV contrast were the test compounds used, which significantly increased penetration. The effect was not due to changes in the red cell concentration or red cell size, at least in the case of dextran, because changes were not significantly different then the saline control. Therefore, this study suggests a feasibility of index matching for increasing OCT imaging through blood.