Determination of cholesterol in atherosclerotic plaques using near infrared diffuse reflection spectroscopy

The aim of this investigation was to examine whether near infrared diffuse reflection spectroscopy is an acceptable tool for the determination of chol esterol content in atherosclerotic plaques. Using an FT-spectrophotometer ( lambda = 1000-2500 nm) and fiberoptic systems (d = 4 mm), the cholesterol c ontent could be determined in mixtures of the primary compounds of the aort ic wall with acceptable precision. Considering the inhomogeneous distributi on of cholesterol and cholesterol esters in atherosclerotic plaques the det ermination of total cholesterol using this method is of acceptable efficacy , even though the calibration procedure did not reflect the composition cor rectly. Using an energy dose of less than 100 mW/cm(2) to avoid damage to e ndothelial cells, arterial tissue of about 170-200 um thickness attenuates the reflected NIRS signal by up to 50%. Cholesterol levels could be determi ned accurately in atherosclerotic lesions in human aortic specimens obtaine d by autopsy. The correlation coefficient between the NIRS results and thos e of HPLC analysis calculated in the investigation of 82 different areas of 18 human aortic specimens was 0.926 (y = 0.869x +/- 0.771, external valida tion). Acceptable results were also achieved by means of a coronary-cathete rlike fiberoptic strand (d = 1 mm), despite the worsened signal/noise ratio . The results show that the development of a coronary catheter using NIRS a ppears to be possible in principle. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.