This novel catheter-based NIRS system accurately identified lipid core plaques through blood in a prospective study in coronary autopsy specimens. It is expected that this novel capability will be of assistance in the management of patients with coronary artery disease.

The controlled release of growth factors from porous, polymer scaffolds is being studied for potential use as tissue-engineered scaffolds. Biodegradable polymer microspheres were coated with a biocompatible polymer membrane to permit the incorporation of the microspheres into tissue-engineered scaffolds. Surface studies with poly(D,L-lactic-co-glycolic acid) [PLGA], and poly(vinyl alcohol) [PVA] were conducted. Polymer films were dip-coated onto glass slides and water contact angles were measured. The contact angles revealed an initially hydrophobic PLGA film, which became hydrophilic after PVA coating. After immersion in water, the PVA coating was removed and a hydrophobic PLGA film remained. Following optimization using these 2D contact angle studies, biodegradable PLGA microspheres were prepared, characterized, and coated with PVA. X-ray photoelectron spectroscopy was used to further characterize coated slides and microspheres. The release of the model protein bovine serum albumin from PVA-coated PLGA microspheres was studied over 8 days. The release of BSA from PVA-coated PLGA microspheres embedded in porous PLGA scaffolds over 24 days was also examined. Coating of the PLGA microspheres with PVA permitted their incorporation into tissue-engineered scaffolds and resulted in a controlled release of BSA.

A noncontact optical detection system is developed for the in vivo identification and localization of high-grade cervical intraepithelial neoplasia (CIN 2,3). Diagnostic scans of the entire human cervix are performed following acetic acid application employing three integrated optical measurements: laser-induced fluorescence spectroscopy, white light diffuse reflectance spectroscopy, and video imaging. Full cervical scans comprising 499 interrogation locations at 1-mm spatial resolution are completed in 12 s. Diffuse reflectance and fluorescence spectra with signal-to-noise ratios of better than 100-to-1 are collected between 360 and 720 nm in increments of 1 nm, with an inherent spectral resolution of 8 nm. Glare reduction and optical vignetting are handled with a novel illumination scheme and subsequent spectral arbitration algorithms. The system is designed and found to be well below acceptable safe optical exposure levels. Typical reproducibility across multiple systems is approximately 5%, providing reliable and accurate detection of in vivo cervical neoplasia in normal clinical use.

Although heart disease remains the leading cause of death in the industrialized world, there is still no method, even under cardiac catheterization, to reliably identify those atherosclerotic lesions most likely to lead to heart attack and death. These lesions, which are often non-stenotic, are frequently comprised of a necrotic, lipid-rich core overlaid with a thin fibrous cap infiltrated with inflammatory cells. InfraReDx has developed a scanning, near-infrared, optical-fiberbased, spectroscopic cardiac catheter system capable of acquiring NIR reflectance spectra from coronary arteries through flowing blood under automated pullback and rotation in order to identify lipid-rich plaques (LRP). The scanning laser source and associated detection electronics produce a spectrum in 5 ms at a collection rate of 40 Hz, yielding thousands of spectra in a single pullback. The system console analyzes the spectral data with a chemometric model, producing a hyperspectral image (a Chemogram, see figure below) that identifies LRP encountered in the region interrogated by the system. We describe the system architecture and components, explain the experimental procedure by which the chemometric model was constructed from spectral data and histology-based reference information collected from autopsy hearts, and provide representative data from ongoing ex vivo and clinical studies.

A catheter-based near infrared spectroscopy (NIRS) system has recently been cleared by the FDA for detection of lipid core containing plaques of interest (LCP) and lipid core burden index (LCBI) in patients undergoing coronary arteriography. NIRS data are plotted as a map (chemogram) of pullback distance versus rotation, with yellow indicating lipid (see below). Analyses for LCP were based on a 2mm block chemogram and LCBI. An algorithm has been developed to perform automated enhancement of the chemogram and facilitate calculation of the number of LCPs (nLCP) in a segment of artery. The goal is to determine if the enhanced algorithm performs as well as the previously validated LCP and LCBI measures, as determined by histology in human coronary autopsy specimens. NIRS data were obtained from 181 segments from 78 hearts and compared with histology at 2 mm intervals. The image analysis was applied to the chemogram and the nLCP calculated. The ROC analysis of the nLCP versus presence of fibroatheroma in each segment yielded an AUC of 0.84 (95% CI 0.77– 0.89). When one or more LCP was detected, 87% sensitivity and 70% specificity were observed for detection of fibroatheroma. The Spearman correlation between nLCP and LCBI was 0.83 (p-value ≤0.0001). The correlation coefficient of nLCP between repeat pullbacks was 0.83 (p-value ≤0.0001). The number of NIRS-detected LCP in chemograms identified with image enhancement correlates well with previously validated measures and the presence of fibroatheroma by histology. This method has the potential to enhance the clinical utility of the chemogram.