Ultrasound-based imaging method for real-time detection of single-heartbeats

Motion-estimation technologies play an important role in diagnosing and monitoring cardiac arrhythmias. One method called electromechanical wave imaging (EWI) is a non-invasive, ultrasound-based imaging method to monitor cardiac function. However, the technique is limited in that it depends on multiple heartbeats, such that it can only resolve periodic cardiac rhythms. Non-periodic arrhythmias such as fibrillation cannot be detected by EWI. The technology described here improves on EWI by modifying it to perform single-heartbeat ultrasound imaging. By independently controlling the motion-estimation and motion-sampling rates, the technology is able to effectively capture single-heartbeats using EWI. With this technology, clinical data on single cardiac heartbeats could be potentially processed in real time for detection of non-periodic cardiac events such as fibrillation.

Increasing frame rate and image resolution in electromechanical wave imaging gathers valuable diagnostic information from a single-heartbeat.

Existing motion-estimation technologies suffer from limitations in their ability to resolve images since they are based on equispace acquisition settings. A frame is created from an ensemble of lines, and the number of lines per frame and the frame rate determines the quality of a resulting image. However, increasing frame rates to capture more data results in a reduced line density while the converse of increasing line density causes a decrease in frame rates. Both trade-offs result in loss of data. This technology overcomes this trade-off by implementing temporally-unequispaced acquisition sequences (TUAS). This method allows for both the local line density and motion-estimation rates to be increased simultaneously, resulting in a significantly reduced acquisition time for EWI and myocardial elastography images. These modifications allow for single heartbeat acquisitions, which can be critical to the diagnosis of cardiac arrhythmias, including ventricular fibrillation. Additionally, this technology can be deployed with conventional clinical ultrasound scanners by executing the TUAS sequence.

In vivo experimentation in a paced canine model with cardiac arrhythmia verified the speed and accuracy of this motion-estimation technology.

Lead Inventor:

Elisa E. Konofagou, Ph.D.

Applications:

• Detect conduction abnormalities in the myocardium.
• Point of care diagnosis for cardiac arrhythmias in expedient situations such as emergency rooms.
• Distinguish unhealthy carotid artery walls with significant plaque buildup from healthy arteries.
• Noninvasive imaging technique for veterinary or research applications.

Advantages:

• Significantly reduces EWI image acquisition time.
• Easily integrated on conventional clinical ultrasound scanners.
• Motion-estimation and motion-sampling rate improvements allow single heartbeat data acquisition.
• Achieves a wide range of frame rates, high resolution and a large field of view to detect non-periodic events.

Patent information:

Patent Pending (US20130066211

Tech Ventures Reference: IR 2945

Related Publications:

• J. Provost, S. Thiebaut, J. Luo, E.E. Konofagou. Single-heartbeat electromechanical wave imaging with optimal strain estimation using temporally-unequispaced acquisition sequences. Physics in Medicine and Biology, Vol. 57, 2012, pp. 1095J-1112.
• J. Provost, V. Gurev, N. Trayanova, E.E. Knofagou. Mapping of cardiac electrical activation with electromechanical wave imaging: An in silico-in vivo reciprocity study. Heart Rhythm, Vol.8, Issue 5, 2011, pp.752-759.
• J. Provost, W.N. Lee, K. Fujikura, E.E. Konofagou. Electromechanical Wave Imaging of Normal and Ischemic Hearts In Vivo, Vol. 29, Issue 3, 2010, pp.625-635.