California Institute of Technology

University of Southern California

Other

Robert H Selzer

Howard N Hodis

David H Blankenhorn

Donald W Crawford

Samuel H Brooks

A standardized acquisition methodology assists operators to accurately replicate high resolution B-mode ultrasound images obtained over several spaced-apart examinations utilizing a split-screen display in which the arterial ultrasound image from an earlier examination is displayed on one side of the screen while a real-time 'live' ultrasound image from a current examination is displayed next to the earlier image on the opposite side of the screen. By viewing both images, whether simultaneously or alternately, while manually adjusting the ultrasound transducer, an operator is able to bring into view the real-time image that best matches a selected image from the earlier ultrasound examination. Utilizing this methodology, dynamic material properties of arterial structures, such as IMT and diameter, are measured in a standard region over successive image frames. Each frame of the sequence has its echo edge boundaries automatically determined by using the immediately prior frame's true echo edge coordinates as initial boundary conditions. Computerized echo edge recognition and tracking over multiple successive image frames enhances measurement of arterial diameter and IMT and allows for improved vascular dimension measurements, including vascular stiffness and IMT determinations.

Split-screen display system and standardized methods for ultrasound image acquisition and multi-frame data processing

High resolution B-mode ultrasound images of the common carotid artery are obtained with an ultrasound transducer using a standardized methodology. Subjects are supine with the head counter-rotated 45 degrees using a head pillow. The jugular vein and carotid artery are located and positioned in a vertical stacked orientation. The transducer is rotated 90 degrees around the centerline of the transverse image of the stacked structure to obtain a longitudinal image while maintaining the vessels in a stacked position. A computerized methodology assists operators to accurately replicate images obtained over several spaced-apart examinations. The methodology utilizes a split-screen display in which the arterial ultrasound image from an earlier examination is displayed on one side of the screen while a real-time 'live' ultrasound image from a current examination is displayed next to the earlier image on the opposite side of the screen. By viewing both images, whether simultaneously or alternately, while manually adjusting the ultrasound transducer, an operator is able to bring into view the real-time image that best matches a selected image from the earlier ultrasound examination. Utilizing this methodology, measurement of vascular dimensions such as carotid arterial IMT and diameter, the coefficient of variation is substantially reduced to values approximating from about 1.0% to about 1.25%. All images contain anatomical landmarks for reproducing probe angulation, including visualization of the carotid bulb, stacking of the jugular vein above the carotid artery, and initial instrumentation settings, used at a baseline measurement are maintained during all follow-up examinations.

System and method for improving ultrasound image acquisition and replication for repeatable measurements of vascular structures

A standardized acquisition methodology assists operators to accurately replicate high resolution B-mode ultrasound images obtained over several spaced-apart examinations. The methodology utilizes a split-screen display in which the arterial ultrasound image from an earlier examination is displayed on one side of the screen while a real-time 'live' ultrasound image from a current examination is displayed next to the earlier image on the opposite side of the screen. A computerized echo edge recognition and tracking methodology automatically identifies ultrasound echo boundaries of the intima-media complex and automatically extracts IMT and arterial dimension measurements, without introducing human measurement error. Measurement accuracy is enhanced by use of sub-pixel resolution for echo edge boundary definition. Utilizing this methodology, measurement of vascular dimensions, such as carotid arterial IMT and diameter, the coefficient of variation is substantially reduced to values approximating from about 1.0% to about 1.25%. Dynamic material properties of arterial structures are measured in a standardized region in accordance with a standardized methodology in order to promote measurement repeatability.

Split-screen display system and standardized methods for ultrasound image acquisition and processing for improved measurements of vascular structures

An image acquisition system and method for generating a subtracted image motion picture as an imaging device moves relative to a subject includes an imaging device for first generating a sequence of first image frames as the imaging device moves along an imaging path under operator control and later generating a sequence of second image frames as the imaging device automatically moves along the same imaging path under processor control. Motion along the imaging path can be duplicated by sensing and storing information indicative of the position of the imaging device relative to the subject as a function of time and later commanding servo motors connected to the imaging device using that position information. Each frame in the first and second sequence of frames has position information stored therewith identifying the location along the imaging path at which each frame was generated. The first and second sequence of frames may then be aligned using the position information and subtracted on a frame-by-frame basis to obtain a subtraction image motion picture essentially free of background interference to detect change over time. The first and second motion pictures may be made at different points of time under similar circumstances either with or without the use of a contrast medium, and subtracted to obtain a difference picture to highlight changes over time.

System and method for dynamic background subtraction

A method and apparatus for angiography in which information contained within multiple serial images of contrast medium flowing through a blood vessel is combined to form a single image having improved vessel edge delineation. More specifically, a method is disclosed whereby a contrast medium opaque to X-rays is injected into a blood vessel distant from an artery section of interest, preferably injected into a vein, whereby the contrast medium is mixed with blood prior to its passing through the artery section. Multiple X-ray images are obtained as the contrast medium and blood mixture flows through the artery section. These multiple images are registered with respect to each other according to a landmark contained within the patient, the landmark having a predetermined relationship to the vessel of interest. The landmark could be a bone, catheter or any other material opaque to X-rays. Density measurements are made with respect to each corresponding image segment or element of the multiple images and are combined to synthesize a composite image. The synthesized image has an edge uncertainty equal to that of one of the individual images divided by the square root of the total number of images utilized.

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Los Angeles, CA, United States of America

Robert H Selzer