Changes in total fluorescence intensity resulting from laser penetration depth in human arteries

Biqing Ye; George S. Abela M.D.

doi:10.1117/12.17512

1 July 1990 Changes in total fluorescence intensity resulting from laser penetration depth in human arteries

Biqing Ye, George S. Abela M.D.

Proceedings Volume 1201, Optical Fibers in Medicine V; (1990) https://doi.org/10.1117/12.17512
Event: OE/LASE '90, 1990, Los Angeles, CA, United States

Abstract

The dependence of total fluorescence intensity emitted from normal artery on laser excitation power (30 mw - 230 mw) at 514 nm was studied. Variations in fluorescence profile and total fluorescence intensity were explored for normal arteries (n=13) and fibrous atheromas (n=32) using 488 nm laser excitation at 30 mw and 514 nm laser excitation at 40 mw respectively. In addition to changes in fluorescence profile, the total fluorescence intensity was considerably different for normal artery specimens and fibrous atheromas. The total fluorescence from normal artery was found to be twice as great as that from fibrous atheroma. A theoretical multi-layer model based on Beer's law was developed. This analysis was used to show that changes in total fluorescence intensity may be due to the variance in laser penetration depth in tissue when an incident laser of constant intensity was used. With the known absorption coefficients for plaque and normal wall at 488 and 514 nm excitation the calculations of total fluorescence intensity were made at tissue depths when the incident beam reached 1 mw. Thus according to the model, the penetration depth in normal artery is 1.70 mm and in fibrous atheroma is 0.85 mm at 488 nm laser excitation and 30 mw. The ratio of the total fluorescence from normal artery to that from atherosclerosis was calculated to be 1.8 multiplied by the ratio of their fluorescence coefficients. Also, the laser penetration depth in normal artery increased with the increase of the laser excitation power at 514 nm. The computed total fluorescence intensity was highly correlated with the experimental results obtained from tissue fluorescence (R = 0.996). Thus experimental results obtained from fresh necropsy normal and atherosclerotic

Citation Download Citation

Biqing Ye and George S. Abela M.D. "Changes in total fluorescence intensity resulting from laser penetration depth in human arteries", Proc. SPIE 1201, Optical Fibers in Medicine V, (1 July 1990); https://doi.org/10.1117/12.17512

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