Abstract:
An ultrasound imaging system includes an ultrasound probe having an array of transducer elements divided into a plurality of contiguous transmit sub-apertures. A plurality of transmitters coupled to the sub-apertures of the ultrasound transducer apply respective transmit signals to the sub-apertures at different frequencies and with delays that cause respective transmit beams emanating from the sub-apertures to overlap each other in a region of interest. A multiline beamformer coupled to the transducer elements processes signals corresponding to ultrasound echoes to output image signals. A processor receives the image signals from the multiline beamformer and outputs image data corresponding to the image signals. The image data are processed by an image processor to output corresponding display signals that are applied to a display.
Abstract:
The invention relates to a method for detecting and imaging ultrasound echo signals returned from a target object comprising microbubbles, said microbubbles being characterized by a resonance frequency, said method comprising the steps of irradiating said target object with at least a first and second successive excitation signals, said first excitation signal being a sweep of increasing frequency with time, and said second excitation signal being a sweep of decreasing frequency with time, detecting echo signals of said first and second excitation signals from said target object, and, combining said echo signals. The maximum frequencies of said first and second excitation signals are lower than said resonance frequency. The invention also relates to an imaging apparatus.
Abstract:
An ultrasonic diagnostic imaging system and method are described for performing nonlinear echo signal imaging with harmonic and intermodulation product (sum or difference frequency) components. Both the harmonic and the intermodulation products are produced by nonlinear effects of tissue or contrast agents and both are advantageously separated from the fundamental transmit components of the echo signals by pulse inversion processing. The use of both nonlinear components can improve the signal to noise ratio of the ultrasonic images, and the two types of components can be blended or used in different regions of an image to offset the effects of depth dependent attenuation.
Abstract:
An ultrasound system (1) is disclosed that comprises a probe (10) including an array (110) of CMUT (capacitive micromachined ultrasound transducer) cells (100), each cell comprising a substrate (112) carrying a first electrode (122), the substrate being spatially separated from a flexible membrane (114) including a second electrode (120) by a gap (118); and a bias voltage source (45) coupled to said probe and adapted to provide the respective first electrodes and second electrodes of at least some of the CMUT cells with a monotonically varying bias voltage including a monotonically varying frequency modulation in a transmission mode of said probe such that the CMUT cells are operated in a collapsed state and transmit at least one chirped pulse during said transmission mode. Such a system for instance may be an ultrasound imaging system or an ultrasound therapeutic system. An ultrasonic pulse generation method using such as system is also disclosed.
Abstract:
An ultrasound system is disclosed wherein an encoded signal is emitted into a patient. A B-mode image is formed by decoding a harmonic of an echo signal and the Doppler image is formed by decoding the fundamental of the echo signal. Decoding includes convolving the echo signal with a time-reversed fundamental or harmonic of the code used to generate the encoded signal. The code may be a linear frequency modulated pulse.
Abstract:
An acoustical imaging system (10) for producing high resolution medical images provides a method and apparatus for obtaining accurate velocity characterizations of samples within the human body, and for obtaining high resolution images of the samples by utilizing the velocity characterizations of the samples within the human body. The acoustical imaging system (10) also provides a method and apparatus for efficient use of switching channels whereby for a transducer array (11) having a plurality of transducer elements, a set of receiver channels (18) which number less than the number of tranducer elements in the array (11) are assigned to a selected portion of the plurality of transducers in the array, wherein for any predetermined set of transducers symmetrically located about a selected transducer, the predetermined set equal in number to the number of receiver channels (18) in the system, each receiver channel in the set of receiver channels (18) is only assigned to one transducer in said predetermined sampling set.
Abstract:
A method and system of producing an ultrasound image of an imaging region of a body, the image comprising pixels, the method comprising: ° a) transmitting time-varying ultrasound into the imaging region, over a time interval, from a surface of the body, the transmitted ultrasound simultaneously having an angular spread in the imaging region corresponding to a plurality of the pixels of the image; and ° b) receiving echoes of the transmitted ultrasound, and recording re ceived signals of the echoes; ° c) combining the received signals at the different sub-intervals of the time interval based on said time varying, according to expected ultrasound propagation times to scatterers localized at different pixels, to find image densities at the pixels.
Abstract:
When an ultrasound transducer is driven by a signal that contains a relatively wide range of frequencies, the frequency-dependent attenuation characteristics of the subject being imaged can be relied on to simultaneously provide, using only a single pulse per line of the image, (a) a return from the deeper portions of the image that is dominated by lower frequencies and (b) a return from the shallower portions of the image that is dominated by higher frequencies. These returns are processed into an image with higher resolution in the shallower parts, and lower resolution with adequate SNR in the deeper parts.