Optical imaging of blood circulation velocities
First Claim
1. A method of measuring blood velocity in tissue, comprising the steps of:
- illuminating a tissue surface with laser energy;
reflecting laser energy from the tissue surface and from near surface levels of the tissue;
receiving the reflected and scattered laser energy on a detector array;
detecting spatial distribution of speckle pattern of the reflected and scattered laser energy;
analyzing the detected energy for laser energy scattering;
computing the effects of multiple scattering induced by the movements of red blood cells and incorporating multiple scattering effects into the analysis of laser speckle statistics, and;
evaluating the laser speckle to obtain a function of blood velocity distribution;
and thereby determining blood velocity and perfusion, and viability of tissue in skin flaps, grafts and organs.
2 Assignments
0 Petitions
Accused Products
Abstract
New devices and methods are provided for noninvasive and noncontact real-time measurements of tissue blood velocity. The invention uses a digital imaging device such as a detector array that allows independent intensity measurements at each pixel to capture images of laser speckle patterns on any surfaces, such as tissue surfaces. The laser speckle is generated by illuminating the surface of interest with an expanded beam from a laser source such as a laser diode or a HeNe laser as long as the detector can detect that particular laser radiation. Digitized speckle images are analyzed using new algorithms for tissue optics and blood optics employing multiple scattering analysis and laser Doppler velocimetry analysis. The resultant two-dimensional images can be displayed on a color monitor and superimposed on images of the tissues.
143 Citations
30 Claims
-
1. A method of measuring blood velocity in tissue, comprising the steps of:
-
illuminating a tissue surface with laser energy; reflecting laser energy from the tissue surface and from near surface levels of the tissue; receiving the reflected and scattered laser energy on a detector array; detecting spatial distribution of speckle pattern of the reflected and scattered laser energy; analyzing the detected energy for laser energy scattering; computing the effects of multiple scattering induced by the movements of red blood cells and incorporating multiple scattering effects into the analysis of laser speckle statistics, and; evaluating the laser speckle to obtain a function of blood velocity distribution; and thereby determining blood velocity and perfusion, and viability of tissue in skin flaps, grafts and organs. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. Apparatus for determining blood velocities in tissues, comprising:
-
a laser for producing a laser beam; a beam expander in optical alignment with the laser for expanding the laser beam for illuminating an area of a tissue with the laser beam; a receiver for receiving reflected and scattered laser energy from the tissue; the receiver having a detector array, for detecting spatial distribution of speckle pattern of surface reflection and scattering of the laser energy from the tissue; an analyzer connected to the detector array for analyzing laser speckle related to red blood cell velocities in the illuminated tissue area; and wherein the analyzer analyzes spatial distribution of speckle intensity. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
-
-
21. Apparatus for assessing blood velocities in tissues, comprising:
-
a mount; a laser on the mount for producing a laser beam; a beam expanding system such as a lens on the mount in optical alignment with the laser for expanding the laser beam and for directing the laser beam to a tissue to be examined for blood velocities; a receiver on the mount for receiving reflected and scattered laser energy from the tissue; the receiver having a laser filter for blocking entry of ambient light; a field stop in optical alignment with a detector for controlling the depth of field of receiving the reflected and scattered laser energy from the tissue; a shutter in optical alignment with the field stop for controlling the length of time for receiving reflected and scattered laser energy from the tissue; a detector comprising an array, in optical alignment with the field stop, the filter, and the shutter for detecting spatial distribution of speckle pattern of reflected and scattered laser energy; a light collecting system such as a multiple-element collecting lens in optical alignment with the filter, the field stop, and the shutter for collecting reflected and scattered laser energy from the tissue and matching the size of the image to the detector array. - View Dependent Claims (22, 23)
-
-
24. A method of determining blood velocity in tissue, comprising:
-
turning on a laser; setting shutter speed, detector gain, and aperture; triggering a shutter; interrogating a detector; obtaining a laser speckle image from the detector; and
computing speckle contrast from a spatial distribution of speckle pattern of the laser speckle image data obtained from the detector;and determining blood velocity and perfusion and viability of tissue in skin flaps, grafts and organs. - View Dependent Claims (25)
-
-
26. A method of obtaining tissue blood velocity data comprising:
-
turning on a laser; aiming the laser at a tissue surface; setting shutter speed; setting detector gain; setting aperture; triggering a shutter; interrogating a detector; obtaining a laser speckle image; determining if any pixels in the image are saturated; when pixels are saturated, resetting shutter speed, detector gain, and aperture; triggering the shutter; interrogating the detector; obtaining detector data; obtaining a laser speckle image; determining if pixels in the image are saturated; if no pixels are saturated, computing speckle contrast from a spatial distribution of speckle pattern of the laser speckle image obtained from the detector data; using multiple scattering correction; obtaining characteristic velocity; mapping the characteristic velocity on the visual image; displaying the velocity mapping; and archiving data; and determining blood velocity and perfusion, and viability of tissue in skin flaps, grafts and organs. - View Dependent Claims (27)
-
-
28. A method of measuring blood velocities in tissues comprising:
-
opening a shutter; illuminating an area of a tissue with a laser for a predetermined exposure time; concurrently receiving reflected and scattered laser energy from the tissue; detecting spatial distribution of speckle pattern of the laser energy with a detector array; closing the shutter; examining spatial distribution of intensity fluctuation time averaged over the exposure time; and determining blood velocities and perfusion in the tissue and viability of the tissue according to the time averaged spatial distribution of intensity fluctuation. - View Dependent Claims (29, 30)
-
Specification