No abstract

We describe an advanced real-time high-speed echocardiographic system with live display while scanning. Images are acquired at rates up to 1000 per second for adult cardiac applications and are stored in computer memory. Images may be played back in slow motion or frame by frame to analyze cardiac motion at the millisecond time scale. Images are acquired using the T5 Duke University Phased Array Scanner that allows 32:1 hardware parallel processing in receive and uses a defocused transmit beam. Clinical scans of 70 patients at rates of 240 to 1000 fps showed adequate image quality for diagnostic purpose. We anticipate that high temporal resolution cardiac images will enable the realization of more accurate and new quantitative descriptors of cardiac function in disease and health.

Recently, we have developed a high frame rate echocardiographic imaging system capable of acquiring images at rates up to 2500 per second. High imaging rates were used to quantify longitudinal strain parameters in patients with echocardiographic normal function. This data can serve as a

This study aims to describe a feature tracking algorithm tailored to estimate circumferential strain on high frame rate ultrasound (HFR-US) images. The algorithm used the Hungarian assignment algorithm for tracking a basic feature descriptor. A second order Kalman model was used to recursively describe regional myocardial displacement along the myocardial contour, and the strain was calculated using these displacements. HFR-US images at 360 fps were acquired from a patient with left bundle branch block (LBBB) in the parasternal short axis view with a biventricular (BiV) pacer turned off and on. There was a large variation in the onset and end of mechanical contraction for each individual myocardial region when the BiV pacer was turned off. The variation reduced immediately when the BiV pacer was turned on. The presented algorithm can estimate circumferential strain using high frame rate ultrasound images. The circumferential strain does suffer from high intra-and inter-operator variance due to the lack of landmarks making it difficult to reproduce results. However, as circumferential and longitudinal strain offer two different, but somehow interrelated, descriptors of complex mechanical movement of the heart. The observed variance reduction may be indicative for a positive BiV response in LBBB patients.

No abstract