Method and apparatus to produce ultrasonic images using multiple apertures

Inventors

Specht, Donald F.

Abstract

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.

Core Innovation

The invention relates to an ultrasound imaging method that uses a first transducer array positioned in a first acoustic window and a second transducer array positioned in a second acoustic window. Ultrasonic energy is transmitted into a target object from the first transducer array, and echoes are received with a first single element of the second transducer array positioned in the second acoustic window. Position information for the first single element relative to the first transducer array is obtained by constructing x1 and y1 position data from a first time at which the first echoes are received at the first transducer array and a second time at which the first echoes are received at the second transducer array.

Second ultrasonic energy is transmitted into the target object from the second transducer array positioned in the second acoustic window, and second echoes are received with a second single element of the first transducer array. Second position information describing a second position of the second single element relative to the second transducer array is obtained by constructing x2 and y2 position data from a third time when the second echoes are received at the second transducer array and a fourth time when the second echoes are received at the first transducer array. A z offset is computed between the x1 and y1 position data and the x2 and y2 position data, and a minimum error squared error estimate of the first and second position information is obtained.

The method adjusts a geometric delay created by a speed of sound difference on an echo return path to the first and second transducer arrays using the minimum error squared error estimate. Related implementations described include separating transmit and receive roles between an insonifying probe and omni-directional receive transducers placed in different acoustic windows, storing echoes and re-mapping them into a two-dimensional sector scan image using depth/time-of-flight based on omni position, and combining image content across omni probes to improve signal-to-noise and lateral resolution while compensating for ultrasound velocity and delay differences.

Claims Coverage

The independently claimed method covers an ultrasound imaging method using two transducer arrays in two acoustic windows to estimate relative position information (x1, y1 and x2, y2), compute a z offset, obtain a minimum error squared error estimate, and adjust geometric delay due to a speed of sound difference. The independent claim contains four core inventive features.

Across the independent claim, the inventive coverage is directed to cross-window echo timing to construct x1/y1 and x2/y2 position information, compute a z offset and a minimum error squared error estimate, and use that estimate to adjust geometric delay created by a speed of sound difference on an echo return path.

Stated Advantages

Documented Applications