System and method for shear wave elastography by transmitting ultrasound with subgroups of ultrasound transducer elements
Systems and methods for performing shear wave elastography using push and/or detection ultrasound beams that are generated by subsets of the available number of transducer elements in an ultrasound transducer. These techniques provide several advantages over currently available approaches to shear wave elastography, including the ability to use a standard, low frame rate ultrasound imaging system and the ability to measure shear wave speed throughout the entire field-of-view rather than only those regions where the push beams are not generated.
1. A method for measuring a mechanical property of an object using an ultrasound system that includes an ultrasound transducer, the steps of the method comprising:
a) inducing at least one shear wave in the object;
b) acquiring elastography data from the object using at least one subgroup of transducer elements by:
i) after inducing the at least one shear wave in the object, successively imaging a plurality of regions in the object using different pulse-echo acquisitions;
ii) detecting shear wave signals associated with the at least one shear wave induced in the object in step a) at each of the plurality of regions; and
iii) processing the shear wave signals to compensate for time grid differences associated with the shear wave signals acquired at different ones of the plurality of regions being acquired at different times after the at least one shear wave was induced in the object in step a);
c) calculating a mechanical property of the object from the compensated shear wave signals;
wherein step b)iii) includes interpolating the shear wave signals from different ones of the plurality of regions to a common time grid in order to align and synchronize time grids associated with each shear wave signal to the common time grid, thereby compensating for the time grid differences in the elastography data.
2. The method as recited in claim 1 , wherein calculating the mechanical property in step c) includes using at least one of a time-to-peak method, a cross-correlation method, a direct inversion method, and a frequency dependent analysis method.
3. The method as recited in claim 1 , wherein a different ultrasound beam is generated for each of the plurality of different regions by using a different subgroup of the transducer elements for each different region.
4. The method as recited in claim 1 , wherein the at least one subgroup of transducer elements comprises a plurality of subgroups of transducer elements, and wherein at least some of the plurality of subgroups of transducer elements contain overlapping transducer elements.
5. The method as recited in claim 1 , wherein steps b)i) and b)ii) include imaging a region by forming a plurality of ultrasound imaging lines in parallel from a single pulse-echo acquisition.
6. The method as recited in claim 1 , wherein the at least one shear wave is induced in step a) using at least one of an ultrasound radiation force, physiological motion, or a mechanical vibration.
7. The method as recited in claim 1 , wherein steps b)i) and b)ii) include repeatedly imaging multiple regions, wherein each of the multiple regions is imaged in a same sequential order.
8. The method as recited in claim 1 , wherein step c) includes applying a directional filter to the elastography data acquired in step b) such that interference between shear waves propagating in different directions is substantially mitigated.