Arterial probe for OCT

#The invention relates to devices for luminal diagnostics, and in particular, to detecting vulnerable plaque.

#Atherosclerosis is a vascular disease characterized by a modification of the walls of blood-carrying vessels. Such modifications, when they occur at discrete locations or pockets of diseased vessels, are referred to as plaques. Certain types of plaques are associated with acute events such as stroke or myocardial infarction. These plaques are referred to as “vulnerable plaques.” A vulnerable plaque typically includes a lipid-containing pool separated from the blood by a thin fibrous cap. In response to elevated intraluminal pressure or vasospasm, the fibrous cap can become disrupted, exposing the contents of the plaque to the flowing blood. The resulting thrombus can lead to ischemia or to the shedding of emboli.

#One method of locating vulnerable plaque is to peer through the arterial wall with infrared light. To do so, one inserts a catheter through the lumen of the artery. The catheter includes a delivery fiber for illuminating a spot on the arterial wall with infrared light. A portion of the light penetrates the blood and arterial wall, scatters off structures within the wall and re-enters the lumen. This re-entrant light can be collected by a collection fiber within the catheter and subjected to spectroscopic analysis. This type of diffuse reflectance spectroscopy can be used to determine chemical composition of arterial tissue, including key constituents believed to be associated with vulnerable plaque such as lipid content.

#FIGS. 1A-1D are schematic diagrams of embodiments of a vulnerable plaque detection system for identifying vulnerable plaque.

#FIG. 2 is a schematic view of a probe in contact with the arterial wall.

#FIG. 3 is a cross-section of the probe of FIG. 2.

#The vulnerability of a plaque to rupture can be assessed by detecting a combination of attributes such as macrophage presence, local temperature rise, and a lipid-rich pool covered by a thin fibrous cap. Some detection modalities are only suited to detecting one of these attributes.

#FIGS. 1A-1D show embodiments 100A-100D of a vulnerable plaque detection system (VPDS) that combines two detection modalities for identifying vulnerable plaque 102 in an arterial wall 104 of a patient. The combination of both chemical analysis, using infrared spectroscopy to detect lipid content, and morphometric analysis, using sub-surface imaging (e.g., optical coherence tomography (OCT) or optical frequency domain reflectometry (OFDR)) to detect cap thickness, enables greater selectivity in identifying potentially vulnerable plaques than either detection modality alone.

#Referring to FIG. 1A, in a first embodiment, a VPDS 100A includes a probe 106 to be inserted into a selected artery, e.g. a coronary artery, of the patient. A first optical waveguide 108 (e.g., an optical fiber) extends between a distal end 110 and a proximal end 112 of the probe 106 for collecting scattered optical radiation for spectroscopic analysis of the arterial wall 104. A second optical waveguide 114 also extends between the distal end 110 and the proximal end 112 of the probe 106 and is part of an interferometer for sub-surface imaging of the arterial wall 104. Optical radiation for both sub-surface imaging and spectroscopic analysis is delivered to the arterial wall through the second optical waveguide 114. An optical delivery and collection head 115 includes one or more optical couplers in optical communication with distal ends of the first and second optical waveguides to couple light from the arterial wall into the first and second optical waveguides, as described in more detail below.