A digital multigate doppler method for high frequency ultrasound

2014-2015 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Embedded system for real-time digital processing of medical Ultrasound Doppler signals

Ultrasound (US) Doppler systems are routinely used for the diagnosis of cardiovascular diseases. Depending on the application, either single tone bursts or more complex waveforms are periodically transmitted throughout a piezoelectric transducer towards the region of interest. Extraction of Doppler information from echoes backscattered from moving blood cells typically involves coherent demodulation and matched filtering of the received signal, followed by a suitable processing module. In this paper, we present an embedded Doppler US system which has been designed as open research platform, programmable according to a variety of strategies in both transmission and reception. By suitably sharing the processing tasks between a state-of-the-art FGPA and a DSP, the system can be used in several medical US applications. As reference examples, the detection of microemboli in cerebral circulation and the measurement of wall _distension_ in carotid arteries are finally presented

Development of a method for calculation of cardiac output using Doppler ultrasound

Cardiac output is the amount of blood pumped by the heart in one minute. The Doppler effect can be used to measure cardiac output by measuring the peak frequency, which is directly proportional to the velocity of blood flowing in the aorta, associated with the Doppler shift signal when an ultrasound beam is incident on the aorta. Stroke volume is the product of the cross sectional area of the aorta and the integration of peak velocity over time. Stroke volume times the heart rate is the cardiac output. This project attempts to develop an algorithm that would automatically calculates the peak frequency from the shift signal and derive the cardiac output. The difference in the power levels in the FFT of the signal in the presence and absence of blood flow is the major discriminating factor used in the peak frequency detection. Eventually, this algorithm will be used to analyze data for understanding the mechanism for a cardiovascular abnormality called the orthostatic intolerance, which is found in astronauts returning from space as well as people on earth