Endoscopic ultrasound Doppler probes for velocity measurements in vessels in the upper gastrointestinal tract using a multifrequency pulsed Doppler meter

Abstract

To quantify flow velocity in vascular structures in the upper gastrointestinal tract, prototype ultrasound Doppler transducers having frequencies of 5 and 10 MHz were designed. Connected to an advanced pulse ultrasound Doppler meter via an isolation transformer for patient safety, these transducers enabled the recording of flow velocity in vessels within an surrounding the wall of the GI tract. This set up improves the endoscopic ultrasound Doppler method by extending the measurable depth-range by using two frequencies, permitting independent selection of measuring depth and sample volume length, and giving an output format which includes full spectral analysis, simultaneous ECG and capabilities of displaying two additional signals.