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Subharmonic aided pressure estimation (SHAPE) is based on the inverse relationship between the subharmonic amplitude of contrast microbubbles (obtained by transmitting at the fundamental frequency fo and receiving at fo/2) and the ambient pressure (see fig.1).

A noninvasive ultrasound based pressure estimation procedure would be a major development in the diagnosis of portal hypertension and less invasive than the current catheter-based hepatic venous pressure gradient (HVPG) measurement.

The hypothesis of this study was that portal vein pressures can be monitored and quantified noninvasively in humans using SHAPE.

First selected waveforms were optimized in vitro and in canines, then SHAPE was correlated with measured HVPG in patients undergoing a transjugular liver biopsy (TJLB).

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Gastroenterology | Medicine and Health Sciences | Radiology

Pulse Shaping for Improved Diagnosis of Portal Hypertension Using Subharmonic Aided Pressure Estimation