Neural network and conventional classifiers for fluorescence-guided laser angioplasty

Abstract

In laser angioplasty, fluorescence spectra of targeted tissue may be used to classify the tissue as atherosclerotic or normal and guide selective laser ablation of atherosclerotic plaque. Here, the ability of the back-propagation and K-nearest neighbors techniques to classify arterial fluorescence spectra is investigated. Both methods are competitive with other classification schemes. The relative performance of variations on both techniques is used to make inferences about the geometry of the classification task.

Discrimination of Human Coronary Artery Atherosclerotic Lipid-Rich Lesions by Time-Resolved Laser-Induced Fluorescence Spectroscopy

“…These morphocompositional differences have been reported to be reflected on the spectral emission trends of the 2 types of arterial tissue. 13,24 Higher values of the emission intensity were reported 18,37 for normal aortic wall (intensity in the red range: Ϸ80% of main peak value) relative to those found for normal coronary artery (Ϸ65%) in this study. Also, the time-dependent emission of normal aorta was shorter (Ϸ11 ns at the main peak region) than that of normal coronary artery (Ϸ14 ns).…”

“…The spectral emission of coronary artery has been reported for both ex vivo 9,10,23,24 and in vivo 12,13 investigation and for various excitation wavelengths: 308 nm, 12 325 nm, 23,24 337 nm, 10 and 476 nm. 9 The time-integrated spectra of normal coronary artery described by our study are in agreement with the emission spectra reported by the research groups that used 337 nm and 325 nm for excitation.…”

“…These results are in agreement with the histopathological analysis of arterial samples as well as with the early interpretation of the origin of arterial wall fluorescence. 24 Also, it is known that both types I and III collagen are the major collagen types in the arterial wall. Immunological studies 36 have shown that type III collagen is localized in the subendothelial space of the normal intima, but no type I collagen was found at that location.…”

“…9 The time-integrated spectra of normal coronary artery described by our study are in agreement with the emission spectra reported by the research groups that used 337 nm and 325 nm for excitation. 10,24 Their emission was characterized by a broad spectrum (360-to 550-nm range; peak 380 to 390 nm), modulated by a valley at Ϸ415 nm. Furthermore, Andersson-Engels et al 10 and Gindi et al 24 showed that the emission of atherosclerotic lesions was reduced at longer wavelengths compared with the emission of normal coronary arterial wall.…”

“…10,24 Their emission was characterized by a broad spectrum (360-to 550-nm range; peak 380 to 390 nm), modulated by a valley at Ϸ415 nm. Furthermore, Andersson-Engels et al 10 and Gindi et al 24 showed that the emission of atherosclerotic lesions was reduced at longer wavelengths compared with the emission of normal coronary arterial wall. Our results confirm these early findings by displaying a gradual decrease of the intensity at wavelengths Ͼ420 nm from normal tissue to type V lesions.…”