Francis W. Cutruzzola

Laser-induced fluorescence spectroscopy of human colonic mucosa: Detection of adenomatous transformation

To evaluate the potential of laser-induced fluorescence spectroscopy for the detection of premalignant lesions of the gastrointestinal tract, the hypothesis that adenomatous transformation of colonic mucosa results in an alteration of laser-induced fluorescence that enables its differentiation from normal or hyperplastic tissue was tested. A fiberoptic catheter coupled to a helium-cadmium laser (325 nm) and an optical multichannel analyzer were used to obtain fluorescence spectra (350-600 nm) from 35 normal colonic specimens and 35 resected adenomatous polyps. A score based on six wavelengths was derived by stepwise multivariate linear regression analysis of the spectra. The mean score (+/- SEM) was + 0.86 +/- 0.06 for normal mucosa and -0.86 +/- 0.06 for adenomatous polyps (P less than 0.001). Spectra from an additional 34 normal specimens, 16 adenomatous polyps, and 16 hyperplastic polyps were prospectively classified with accuracies of 100%, 100%, and 94%, respectively. The mean score for hyperplastic polyps was significantly different from adenomatous (P less than 0.001) but not from normal tissue. Thus, quantitative analysis of fluorescence spectra enables the detection of adenomatous transformation in colonic mucosa.

Development and evaluation of spectral classification algorithms for fluorescence guided laser angioplasty

The feasibility of utilizing spectral information to discriminate arterial tissue type is considered. Arterial fluorescence spectra from 350 to 700 nm were obtained from 100 human aortic specimens. Seven spectral classification algorithms were developed with the following techniques: multivariate linear regression, stepwise multivariate linear regression, principal components analysis, decision plane analysis, Bayes decision theory, principal peak ratio, and spectral width. The classification ability of each algorithm was evaluated by its application to the training set and to a validation set containing 82 additional spectra. All seven spectral classification algorithms prospectively classified atherosclerotic and normal aortas with an accuracy greater than 80% (range: 82-96%). Laser angioplasty systems incorporating spectral classification algorithms may therefore be capable of detection and selective ablation of atherosclerotic plaque.<<ETX>>

In-Vivo Fluorescence Spectroscopy Of Normal And Atherosclerotic Arteries

Laser-induced fluorescence spectroscopy can discriminate atherosclerotic from normal arteries in-vitro and may thus potentially guide laser angioplasty. To evaluate the feasibility of laser-induced fluorescence spectroscopy in a living blood-filled arterial system we performed fiberoptic laser-induced fluorescence spectroscopy in a rabbit model of focal femoral atherosclerosis. A laser-induced fluorescence spectroscopy score was derived from stepwise linear regression analysis of in-vitro spectra to distinguish normal aorta (score>0) from atherosclerotic femoral artery (score<0). A 400 u silica fiber, coupled to a helium cadmium laser and optical multichannel analyzer, was inserted through a 5F catheter to induce and record in-vivo fluorescence from femoral and aortoiliac arteries. Arterial spectra could be recorded in all animals (n=10: 5 occlusions, 5 stenoses). Blood spectra were of low intensity and were easily distinguished from arterial spectra. The scores (mean ± SEM) for the in-vivo spectra were -0.69 ± 0.29 for artherosclerotic femoral, and +0.54 ±. 0.15 for normal aorta (p<.01; p=NS compared to in-vitro spectra). In-vitro, a fiber tip to tissue distance <50 u was necessary for adequate arterial LIFS in blood. At larger distances low intensity blood spectra were recorded (1/20 the intensity of tissue spectra). Thus, fiberoptic laser-induced fluorescence spectroscopy can be sucessfully performed in a blood filled artery provided the fiber tip is approximated to the tissue.

Medical Applications of Alexandrite Laser Systems

Alexandrite laser systems have several characteristics which are necessary for laser surgical applications. The relatively long Q-switched pulsewidths allow significant amounts of energy to be transmitted through optical fibers before the onset of fiber damage. The laser output wavelength in the fundamental (720 - 800 nm) and second harmonic (360 - 400 nm) are efficiently transmitted through commercially available fused silica fibers. The alexandrite laser may therefore be the optimal choice for numerous medical applications.

Evaluation of spectral discriminant functions for guidance of laser angioplasty

Development of a clinically acceptable laser angioplasty system has been hindered by the inability to adequately guide ablative laser radiation to atherosclerotic plaque. Low power laser-induced fluorescence spectroscopy is capable of discriminating normal and atherosclerotic arterial tissue. The purpose of this investigation was to develop and evaluate several spectral classification algorithms that would enable discrimination of atherosclerotic and normal arterial tissue by a computer controlled fluorescence guided laser angioplasty system.

Evaluation Of Spectral Discriminant Functions For Guidance Of Laser Angioplasty

Development of a clinically acceptable laser angioplasty system has been hindered by the inability to adequately guide ablative laser radiation to atherosclerotic plaque. Low power laser-induced fluorescence spectroscopy is capable of discriminating normal and atherosclerotic arterial tissue. The purpose of this investigation was to develop and evaluate several spectral classification algorithms that would enable discrimination of atherosclerotic and normal arterial tissue by a computer controlled fluorescence guided laser angioplasty system.