Ultrasonic imaging with multi-scale processing for grating lobe suppression
Aspects of the invention include ultrasound systems that suppress grating lobe artifacts arising due to high frequency operation of an array transducer probe which is operated at a frequency higher than its pitch limitation.
1. An ultrasonic diagnostic imaging system which suppresses grating lobe artifacts comprising:
an ultrasound array adapted to acquire ultrasonic echo signals such that the ultrasonic diagnostic imaging system is adapted to produce, using the ultrasonic echo signals, low frequency and high frequency ultrasound images;
a spatial low pass filter adapted to separate low spatial frequency content of each of the low frequency and high frequency ultrasound images;
a signal separator adapted to separate high frequency content of each of the low frequency and high frequency ultrasound images;
a combiner adapted to combine the low spatial frequency content of the low frequency ultrasound image and the high spatial frequency content of the high frequency ultrasound image; and
a display adapted to display an ultrasound image of the combined low spatial frequency and high frequency content of the low and high frequency ultrasound images in which grating lobe artifacts are suppressed.
2. The ultrasonic diagnostic imaging system of claim 1 , wherein the ultrasound array is adapted to acquire the low frequency ultrasound image in response to the transmission of low frequency ultrasound energy, and to acquire the high frequency ultrasound image in response to the transmission of high frequency ultrasound energy.
3. The ultrasonic diagnostic imaging system of claim 2 , wherein the ultrasound array is adapted to acquire the low frequency ultrasound image and the high frequency ultrasound image by interleaved transmission of pulses of low and high frequency ultrasound energy.
4. The ultrasonic diagnostic imaging system of claim 1 , wherein the ultrasound array is adapted to acquire broad band ultrasonic echo signals for the ultrasound image; and further comprising
a filter adapted to separate the broad band ultrasonic echo signals into signals for a low frequency ultrasound image and a high frequency ultrasound image.
5. The ultrasonic diagnostic imaging system of claim 1 , wherein the spatial low pass filter further comprises a Gaussian filter of a given kernel size.
6. The ultrasonic diagnostic imaging system of claim 1 , wherein the spatial low pass filter further comprises a filter of a given kernel size, wherein the given kernel size comprises a plurality of first pixels around a center pixel and a plurality of second pixels neighboring the plurality of first pixels, wherein the filter is adapted to provide a negative weight for the plurality of first pixels and an increased weight for the plurality of second pixels.
7. The ultrasonic diagnostic imaging system of claim 1 , wherein the spatial low pass filter further comprises a pair of spatial low pass filters adapted to operate on the low frequency and high frequency ultrasound images, respectively.
8. The ultrasonic diagnostic imaging system of claim 1 , wherein the signal separator further comprises a subtractor adapted to subtract the low spatial frequency content produced by the spatial low pass filter from the ultrasound image operated upon by the spatial low pass filter.
9. The ultrasonic diagnostic imaging system of claim 8 , wherein the subtractor further comprises a pair of subtractors adapted to subtract the low spatial frequency content produced by a pair of spatial low pass filters from the ultrasound images operated upon by the spatial low pass filters.
10. The ultrasonic diagnostic imaging system of claim 1 , wherein the combiner further comprises an adder adapted to combine the low spatial frequency content of the low frequency ultrasound image and the high spatial frequency content of the high frequency ultrasound image.
11. The ultrasonic diagnostic imaging system of claim 1 , wherein the ultrasound array further comprises a plurality of transducer elements,
wherein the array is further adapted to acquire ultrasonic echo signals for the high frequency ultrasound image by transmitting ultrasound signals exhibiting a wavelength which is smaller than twice the pitch of the transducer elements.
12. The ultrasonic diagnostic imaging system of claim 11 , wherein the ultrasound array is further adapted to acquire ultrasonic echo signals for the low frequency ultrasound image by transmitting ultrasound signals exhibiting a wavelength which is greater than or equal to twice the pitch of the transducer elements.
13. The ultrasonic diagnostic imaging system of claim 1 , further comprising a log compressor having an input coupled to receive signals produced by the ultrasound array and an output coupled to the spatial low pass filter.
14. The ultrasonic diagnostic imaging system of claim 1 , wherein the combiner is further adapted to select pixels for the displayed ultrasound image in accordance with the low spatial frequency content of the low and high frequency images which exhibits the minimal value.
15. The ultrasonic diagnostic imaging system of claim 1 , wherein the combiner is further adapted to select pixels for the displayed ultrasound image in accordance with a pixel value of the low frequency and high frequency ultrasound images which exhibits the minimal value.
16. The ultrasonic diagnostic imaging system of claim 1 , wherein the ultrasound array is adapted to acquire broad band ultrasonic echo signals for the ultrasound image; and further comprising
a filter adapted to separate the broad band ultrasonic echo signals into signals for a low frequency ultrasound image and a broadband ultrasound image.