Transmission versus reflectance spectroscopy for quantitation.

The objective of this work was to compare the accuracy of analyte concentration estimation when using transmission versus diffuse reflectance spectroscopy of a scattering medium. Monte Carlo ray tracing of light through the medium was used in conjunction with pure component absorption spectra and Beer-Lambert absorption along each ray's pathlength to generate matched sets of pseudoabsorbance spectra, containing water and six analytes present in skin. PLS regression models revealed an improvement in accuracy when using transmission compared to reflectance for a range of medium thicknesses and instrument noise levels.

In vivo validation of a catheter-based near-infrared spectroscopy system for detection of lipid core coronary plaques: initial results of the SPECTACL study.

Objectives: To determine whether catheter-based near-infrared spectroscopy (NIRS) signals obtained with a novel catheter-based system from coronaries of patients are similar to those from autopsy specimens and to assess initial safety of NIRS device.

Background: An intravascular NIRS system for detection of lipid core-containing plaques (LCP) has been validated in human coronary autopsy specimens. The SPECTACL (SPECTroscopic Assessment of Coronary Lipid) trial was a parallel first-in-human multicenter study designed to demonstrate the applicability of the LCP detection algorithm in living patients.

Detection of lipid core coronary plaques in autopsy specimens with a novel catheter-based near-infrared spectroscopy system.

Objectives: This study sought to assess agreement between an intravascular near-infrared spectroscopy (NIRS) system and histology in coronary autopsy specimens.

Background: Lipid core plaques cannot be detected by conventional tests, yet are suspected to be the cause of most acute coronary syndromes. Near-infrared spectroscopy is widely used to determine the chemical content of substances.

Frequency and distribution of thin-cap fibroatheroma and ruptured plaques in human coronary arteries: a pathologic study.

Objectives: Our purpose was to quantify the frequency and distribution of suspected vulnerable lesions, defined as thin-capped fibroatheroma (TCFA) and ruptured plaque, in human coronary artery autopsy specimens.

Background: Most acute coronary events and sudden death are believed to arise from rupture of a TCFA followed by thrombosis. Although there is general agreement that clinical events are usually caused by focal lesions, there is considerable debate over the relative importance of focal versus systemic factors in the pathogenesis of atherosclerosis.

Hyperperfusion syndromes: insight into the pathophysiology and treatment of hypertensive encephalopathy.

Hypertensive encephalopathy is one of the manifestations of a hypertensive crisis. It is not the absolute value of the blood pressure that causes the encephalopathy, rather the presence of an abrupt rise in pressure. In terms of clinical and radiographic findings, there are many similarities among a group of entities, including hypertensive encephalopathy, eclampsia, and immunosuppressant neurotoxicity.