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:
Provided herein are compositions comprising a microbubble contrast agent, wherein at least 20% by volume of the microbubbles in the contrast agent has a size of less than 1 micron, wherein the contrast agent produces non-linear scattering when contacted by ultrasound at a frequency above 20 MHz. Provided herein are compositions comprising a microbubble contrast agent, wherein at least 10% by volume of the microbubbles in the contrast agent has a size of less than 500 nanometers, wherein the contrast agent produces non-linear scattering when contacted by ultrasound at a frequency above 20 MHz. Provided herein are compositions comprising a microbubble contrast agent, wherein at least 5% by volume of the microbubbles in the contrast agent has a size of less than 200 nanometers, wherein the contrast agent produces non-linear scattering when contacted by ultrasound at a frequency above 20 MHz. The disclosed contrast agents can be targeted contrast agents. Further provided are methods of using the compositions disclosed herein. Specifically provided are methods for producing an ultrasound image comprising: administering contrast agent to a laboratory animal; generating ultrasound at a frequency of at least 20 MHz; transmitting ultrasound at a frequency of at least 20 MHz into the subject; receiving non-linear ultrasound from the contrast agent in the subject; processing the received ultrasound to provide an image.
Abstract:
An ultrasonic diagnostic imaging system and method are presented in which the balance between image resolution and frame rate (Res/Speed) and the balance between image resolution and penetration (Pen/Gen/Res) are automatically adjusted in response to image content. A motion detector analyzes the relative motion between successive images. If the motion content is relatively high, the imaging parameters are changed in favor of relatively greater frame rate and reduced resolution. A low motion content causes the opposite adjustment. The electronic noise between successive images is also computed with a relatively high noise content (low correlation) in the far field resulting in an adjustment to penetration as by lowering the transmit frequency. A relatively low noise content causes an adjustment in favor of increased resolution.
Abstract:
A system and method for synchronized persistence with ultrasonic harmonic imaging of both tissue and tissue perfused with a contrast agent are disclosed. The ultrasonic harmonic imaging system comprises a frame memory, a frame processor, a persistence actuator, and a persistence controller. In a preferred embodiment, the persistence actuator disables persistence filtering in response to contrast agent destructive ultrasonic transmissions. A method for observing an ultrasonic response of a contrast agent may be performed by: introducing a contrast agent into tissue targeted for imaging; insonifying the tissue with a first ultrasound transmit signal suited to observe the contrast agent and the tissue; modifying a transmit signal parameter to destroy a substantial portion of the contrast agent; disabling persistence filtering while the modified transmit signal is actuated; and enabling persistence filtering while observing the re-perfusion of the tissue.
Abstract:
An ultrasonic diagnostic imaging system and method are presented to determine low rates of blood flow using contrast agents. Pairs of differently modulated pulses are transmitted in several beam directions to acquire echoes which can be combined to separate harmonic frequencies by pulse inversion. The pulses of each pair are transmitted in rapid succession to minimize motional artifacts. The transmission in the different beam directions is time-interleaved, resulting in the sampling of each beam direction over a long ensemble time for the detection of low rates of flow.
Abstract:
A method and apparatus are described for ultrasonically imaging tiny blood vessels with the aid of a contrast agent. The locations of microbubbles of the contrast agent are detected in a series of images as the microbubbles move through the blood vessels. These images are temporally processed to identify the moving microbubbles, and persistence processed to depict images which show the tracks followed by the microbubbles through the blood vessels. A maximum intensity persistence can be used to show the steady buildup of microbubble tracks through the vasculature, or a slow decay employed so that the tracks will fade to black over time.
Abstract:
The present invention is directed to a method for detecting an ultrasound contrast agent in a soft tissue and quantitating blood perfusion through regions of tissue by detecting the contrast agent in the tissue.
Abstract:
A method and apparatus for performing harmonic imaging. Each transmit focal zone in the near-field is interrogated by two or more transmit firings of different phase, while each transmit focal zone in the far-field is interrogated by a single transmit firing. On receive, the respective near-field vectors are summed, thereby substantially cancelling the fundamental signal components while isolating the (sub)-harmonic signal components. In the far-field, the single transmit firing has a fundamental frequency f0. A filter isolates the signal component having a passband centered at a (sub)-harmonic frequency, e.g., 2f0. The near-field and far-field receive vectors at each scan angle are then stitched together to form a composite vector.