Methods and apparatus for analyzing the chemical composition of vulnerable
plaques with an intravascular catheter having a near-infrared light
source, a fiber-optic probe, a mechanism for directing the light from the
light source into a blood vessel, and detectors for detecting light
reflected or scattered by the tissue. The light source may be a tunable
laser, and may transmit an incident beam having a wavelength ranging from
1400 to 4100 nm. A computer may be included to receive and process the
spectral data in the analysis of the vulnerable plaques. A catheter system
may be configured to provide near-IR spectrometric imaging of arteries to
non-destructively locate and determine lipid pool and fibrous cap size and
composition. Additionally, mediators and cellular components may be also
determined that are typically associated with vulnerable plaques which
have an increased risk of rupture. The lipid pool, fibrous cap, and
inflammatory response may serve as an in vivo marker for vulnerable
atherosclerotic plaques. Methods are further provided for prospectively
identifying and characterizing vulnerable plaques which may include the
steps of focusing near-IR light onto a blood vessel wall; detecting the
scattered light in the region; and analyzing the resulting spectra across
the full preselected wavelength range, particularly in the ranges that
include identifying peaks for vulnerable plaque constituents.
