Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1999-06-17
2001-04-03
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S443000
Reexamination Certificate
active
06210328
ABSTRACT:
This invention relates to ultrasonic diagnostic imaging systems and, in particular, to ultrasonic diagnostic imaging systems which produce spatially compounded images by combining a variable number of received images.
Spatial compounding is an imaging technique in which a number of ultrasound images of a given target that have been obtained from multiple vantage points or angles (look directions) are combined into a single compounded image by combining the data received from each point in the compound image target which has been received from each angle. Examples of spatial compounding may be found in U.S. Pat. Nos. 4,649,927; 4,319,489; and 4,159,462. Real time spatial compound imaging is performed by rapidly acquiring a series of partially overlapping component image frames from substantially independent spatial directions, utilizing an array transducer to implement electronic beam steering and/or electronic translation of the component frames. The component frames are combined into a compound image by summation, averaging, peak detection, or other combinational means. The acquisition sequence and formation of compound images are repeated continuously at a rate limited by the acquisition frame rate, that is, the time required to acquire the full complement of scanlines over the selected width and depth of imaging.
The compounded image typically shows lower speckle and better specular reflector delineation than conventional ultrasound images from a single viewpoint. Speckle is reduced (i.e. speckle signal to noise ratio is improved) by the square root of N in a compound image with N component frames, provided that the component frames used to create the compound image are substantially independent and are averaged. Several criteria can be used to determine the degree of independence of the component frames (see, e.g., O'Donnell et al. in IEEE Trans. UFFC v.35, no.4, pp 470-76 (1988)). In practice, for spatial compound imaging with a steered linear array, this implies a minimum steering angle between component frames. This minimum angle is typically on the order of several degrees.
The second way that spatial compound scanning improves image quality is by improving the acquisition of specular interfaces. For example, a curved bone-soft tissue interface produces a strong echo when the ultrasound beam is exactly perpendicular to the interface, and a very weak echo when the beam is only a few degrees off perpendicular. These interfaces are often curved, and with conventional scanning only a small portion of the interface is visible. Spatial compound scanning acquires views of the interface from many different angles, making the curved interface visible and continuous over a larger field of view. Greater angular diversity generally improves the continuity of specular targets. However, the angular diversity available is limited by the acceptance angle of the transducer array elements. The acceptance angle depends on the transducer array element pitch, frequency, and construction methods.
One of the problems associated with real time spatial compound imaging is that several image acquisitions are needed to produce each new compound image frame. The time needed to acquire a spatial compound image consisting of N component frames is approximately N times longer than that of each individual component frame. It is generally desirable to acquire a large number of component frames to maximize the image quality of the compound image. However, it is also generally desirable to maintain high compound image frame rates of display to facilitate real time examination, leading to a tradeoff between compound image quality and compound image frame rate.
In accordance with the principles of the present invention, the number of different look directions of a target which are compounded is variable in accordance with changes in ultrasound system operating parameters, either singly or in combination, which improves the performance of the spatial compounding system. These parameters include image display depth, acquisition rate, number of scanlines or line density, number of transmit focal zones, amount of deadtime per pulse repetition interval (PRI), number of transmissions per image line, depth of region of greatest compounding, clinical application, number of simultaneous modes, size of region of interest, and mode of operation (e.g., survey or target mode). In accordance with a preferred embodiment of the present invention, the steering angle(s) of the look directions are varied in response to changes in the image depth. In a constructed embodiment an ultrasonic transducer scans a target from a number of different perspectives. For example, several sector images can be sequentially acquired by a phased array transducer, each with an apex located at a different point in relation to the array. As a second example a steered linear array can be used to image the target with a sequence of groups of beams, each group steered at a different angle with respect to the axis of the array. Thirdly, beams having no particular relationship to a frame or image format can interrogate targets in a region of the body from multiple directions, by the transmission of individual beams or multiple beams simultaneously. In either case the received images are processed in the usual way by beamforming and detection and stored in a memory. To form the compound image the component frames or target echoes to be combined are spatially aligned (if not already aligned by a common beam steering reference) by scan conversion or resampling. The common spatial locations in the image field are then compounded by averaging or summing and the resultant compound image is displayed.
REFERENCES:
patent: 4070905 (1978-01-01), Kossoff
patent: 4159462 (1979-06-01), Rocha et al.
patent: 4649327 (1987-03-01), Fehr et al.
patent: 4649927 (1987-03-01), Fehr et al.
patent: 4751846 (1988-06-01), Dousse
patent: 5538004 (1996-07-01), Bamber
patent: 5566674 (1996-10-01), Weng
patent: 5623928 (1997-04-01), Finger et al.
patent: 5655535 (1997-08-01), Teo et al.
patent: 5779641 (1998-07-01), Hatfield et al.
patent: 5782766 (1998-07-01), Weng et al.
patent: 5885218 (1999-03-01), Teo et al.
patent: 5908390 (1999-06-01), Matsushima
Feigenbaum, Echocardiography, Lea & Febiger, 1976 at pp 32-34, Philadelphia, PA.
Carpenter et al., Technical Note—A Multimode Real Time Scanner, Ultrsound in Med. & Biol., vol. 6, pp 279-284, Pergamon Press Ltd. 1980, Great Britain.
Berson et al., Compound Scanning With a Electrically Steered Beam, Ultrasonic Imaging 3, pp 303-308, Academic Press, Inc. 1981.
Shattuck et al., Compound Scanning With a Phased Array, Ultrasonic Imaging 4, pp 93-107, Academic Press, Inc. 1982.
Jesperson et al., Multi-Angle Compound Imaging, Ultrasonic Imaging 20, pp 81-102, Dynamedia, Inc. 1998.
McCann et al., “Multidimensional Ultrasonic Imaging for Cardiology,” Proceedings of the IEEE, U.S., IEEE. New York, vol. 76, No. 9, Sep. 1988 (1988-09) pp 1063 -1072.
Entrekin Robert R.
Jago James R.
Robinson Andrew L.
ATL Ultrasound
Lateef Marvin M.
Patel Maulin
Yorks, Jr. W. Brinton
LandOfFree
Ultrasonic diagnostic imaging system with variable spatial... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultrasonic diagnostic imaging system with variable spatial..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultrasonic diagnostic imaging system with variable spatial... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2533295