Estimation of Tumor Angiogenesis With Contrast Enhanced Subharmonic Ultrasound Imaging

摘要

New contrast-specific imaging modalities such as harmonic imaging (HI) may improve the accuracy of breast ultrasound. Unfortunately, HI suffers from reduced blood-to-tissue contrast resulting from second harmonic generation and accumulation in tissue. As an alternative we propose using subharmonic imaging (SHI) by transmitting at the double the resonance frequency (f0/2) and receiving at the subharmonic (f0). Hence, the current project proposes to increase the ability of breast ultrasound to differentiate between benign and malignant lesions by combining injection of an ultrasound contrast agent with SHI. A dual-transducer pulse-echo system was built to perform in vitro SHI measurements and experiments were conducted in a perfusion phantom with realistic neovascular flow velocities (around 2 mm/s). Up to 12 dB of subharmonic signal components were measured. In vivo animal experiments comparing SH in canines to perfusion showed good correlation r = 0.57; p.