Systems and methods for acoustic radiation force imaging with enhanced performance
Methods and systems for ultrasound imaging are presented. The method includes configuring a plurality of apertures in a transducer array of an ultrasound imaging device, where the apertures include one or more transducer elements. Further, one or more reference pulses are delivered to a plurality of target regions to detect corresponding initial positions. Additionally, a pushing pulse is delivered to at least two of the plurality of target regions through at least two of the plurality of apertures. The plurality of apertures is focused at specific target regions in the plurality of target regions using a compound delay profile. Subsequently, one or more tracking pulses are delivered to the plurality of target regions for detecting corresponding displacements of at least the specific target regions. Further, ultrasound imaging methods that deliver a plurality of short pushing pulse segments and/or tracking pulses to corresponding target regions in an interleaving manner are described.
1. An ultrasound imaging method, comprising:
configuring an overall transmit aperture comprising a plurality of apertures in a transducer array of an ultrasound imaging device, wherein the plurality of apertures comprises one or more transducer elements in the transducer array;
delivering one or more reference pulses to a plurality of target regions to detect initial positions of the plurality of target regions, wherein the plurality of target regions corresponds to two or more regions of a target object having different depth values, different lateral locations, or a combination thereof;
determining a compound delay profile that distributes acoustic power corresponding to a single pushing pulse in an acoustic radiation force impulse imaging sequence to at least two distinct regions in the plurality of target regions to achieve multiple foci operation in a single transmit event using a compound focus;
wherein the compound focus comprises at least two of the plurality of apertures corresponding to distinct portions of the overall transmit aperture;
wherein the at least two distinct regions have different depths, different spatial locations, or a combination thereof; and
wherein the compound delay profile distributes the acoustic power to the two distinct regions so as to achieve a plurality of desired peaks in axial pressure along the plurality of target regions to displace a larger region in the target object and improve uniformity of beam intensity and displacement of the plurality of target regions as compared to a displacement and a beam intensity achieved using a single focus;
delivering the pushing pulse to the two distinct regions in the plurality of target regions using the compound delay profile; and
delivering one or more tracking pulses to the plurality of target regions for detecting corresponding displacements of at least the two distinct regions in the plurality of target regions.
2. The method of claim 1 , further comprising computing the delay profile based on the geometry of the transducer array and a desired depth of field.
3. The method of claim 2 , wherein configuring a plurality of apertures in a transducer array comprises:
selecting the two distinct regions in the plurality of target regions, wherein each of the two distinct regions has a particular depth corresponding to a desired depth of field;
grouping the one or more transducer elements in the transducer array into the plurality of apertures; and
computing the compound delay profile for configuring the plurality of apertures to deliver the pushing pulse to each of the two distinct regions having the particular depth.
4. The method of claim 2 , wherein computing the delay profile comprises continually varying a delay between the one or more transducer elements positioned at the center of the transducer array and the one or more transducer elements positioned at an edge of the transducer array for focusing the one or more transducer elements positioned at the center of the transducer array at a first depth in the desired depth of field, and focusing the one or more transducer elements positioned at the edge of the transducer array at a second depth in the desired depth of field, wherein the second depth is greater than the first depth.
5. The method of claim 2 , wherein computing the delay profile comprises continually varying a delay between the one or more transducer elements as a function of distance of the one or more transducer elements from the center of a corresponding aperture.
6. The method of claim 2 , wherein computing the delay profile comprises selecting the delay profile using an exhaustive search, a directed search, or a combination thereof, of possible discrete delays to achieve the desired peak axial pressure and improve the uniformity of the achieved peak axial pressure along the desired depth of field.
7. The method of claim 1 , further comprising delivering the one or more reference pulses, the one or more tracking pulses, or a combination thereof, in an interleaving manner.
8. The method of claim 1 , wherein detecting the displacements comprises using speckle tracking, a sum of absolute differences, an iterative phase zeroing technique, a direct strain estimation, a cross-correlation, an auto-correlation, or combinations thereof, for detecting the displacement of at least the two distinct regions over a determined period of time.
9. The method of claim 1 , further comprising determining one or more characteristics of the plurality of target regions using data corresponding to the one or more tracking pulses, wherein the one or more characteristics of the plurality of target regions comprises a stiffness, a strain, a velocity, a displacement at a specified instant of time, a peak displacement, a time to reach peak displacement, a time of decay from peak displacement, or combinations thereof.
10. The method of claim 1 , wherein the plurality of target regions comprises a biological tissue or a compressible portion of an object for industrial inspection.