Method and apparatus to produce ultrasonic images using multiple apertures
A combination of an ultrasonic scanner and an omnidirectional receive transducer for producing a two-dimensional image from received echoes is described. Two-dimensional images with different noise components can be constructed from the echoes received by additional transducers. These can be combined to produce images with better signal to noise ratios and lateral resolution. Also disclosed is a method based on information content to compensate for the different delays for different paths through intervening tissue is described. The disclosed techniques have broad application in medical imaging but are ideally suited to multi-aperture cardiac imaging using two or more intercostal spaces. Since lateral resolution is determined primarily by the aperture defined by the end elements, it is not necessary to fill the entire aperture with equally spaced elements. Multiple slices using these methods can be combined to form three-dimensional images.
1. An ultrasound imaging method comprising:
transmitting first ultrasonic energy into a target object to be imaged from a first transducer array positioned in a first acoustic window;
receiving first echoes of the first ultrasonic energy with a first single element of a second transducer array positioned in a second acoustic window;
obtaining first position information describing a first position of the first single element relative to the first transducer array;
constructing a first image of the target object from the first echoes and the first position information;
transmitting second ultrasonic energy into the target object to be imaged from the second transducer array positioned in the second acoustic window;
receiving second echoes of the second ultrasonic energy with a second single element of the first transducer array;
obtaining second position information describing a second position of the second single element relative to the second transducer array;
constructing a second image of the target object from the second echoes and the second position information; and
averaging the first image and the second image.
2. The method of claim 1 , further comprising:
storing the first echoes in a computer memory before constructing the first image.
3. The method of claim 1 , wherein the target object is human tissue.
4. The method of claim 1 , wherein the first transducer array is separated from the second transducer array by a gap.
5. The method of claim 1 , wherein the first transducer array and the second transducer array are aligned with and configured to transmit first and second ultrasonic energy in a common scan plane.
6. The method of claim 1 , wherein the first transducer array and the second transducer array are mounted in a rigid probe.
7. The method of claim 1 , wherein the first transducer array and the second transducer array are mounted in an adjustable, extendable hand held probe.
8. The method of claim 1 , wherein the first transducer array and the second transducer array are mounted in a fixture with articulated joints and sensors configured to measure relative positions of the first transducer array and the second transducer array.
9. The method of claim 1 , wherein the first ultrasound energy comprises a first sector scan.
10. An ultrasound imaging system comprising:
a first transducer array positioned in a first acoustic window and aligned with a scan plane, the first transducer array configured to transmit first ultrasonic energy focused in the scan plane in a target object to be imaged;
a second transducer array positioned in a second acoustic window and aligned with the scan plane, the second transducer array configured to transmit second ultrasonic energy focused in the scan plane in the target object to be imaged;
a computer in electronic communication with the first transducer array and the second transducer array, the computer having hardware and software configured to control the first transducer array and the second transducer array to:
transmit first ultrasonic energy from the first transducer array into the target object in the scan plane;
receive first echoes of the first ultrasonic energy with a first single element of the second transducer array;
obtain first position information describing a first position of the first single element relative to the first transducer array;
construct a first image of the target object from the first echoes and the first position information;
transmit second ultrasonic energy from the second transducer array into the target object in the scan plane;
receive second echoes of the second ultrasonic energy with a second single element of the first transducer array;
obtain second position information describing a second position of the second single element relative to the second transducer array;
construct a second image of the target object from the second echoes and the second position information; and
average the first image and the second image.
11. The system of claim 10 , further comprising a computer memory, and wherein the computer is further configured to store the first echoes in the computer memory before constructing the first image.
12. The system of claim 10 , wherein the target object is human tissue, and wherein the first acoustic window is selected from the group consisting of a first parasternal intercostal space, a second parasternal intercostal space, a suprasternal notch, a substernal position, a subcostal window, an apical view, a first intercostal space adjacent the sternum, and a second intercostal space adjacent the sternum, and wherein the second acoustic window is selected from the same group.
13. The system of claim 10 , wherein the first transducer array is separated from the second transducer array by a gap.
14. The system of claim 10 , wherein the first transducer array and the second transducer array are mounted in a rigid probe.
15. The system of claim 10 , wherein the first transducer array and the second transducer array are mounted in an adjustable, extendable hand held probe.
16. The system of claim 10 , wherein the first transducer array and the second transducer array are mounted in a fixture with articulated joints and sensors configured to measure relative positions of the first transducer array and the second transducer array.
17. The system of claim 10 , wherein the first ultrasound energy comprises a first sector scan.