Detection of early tumor response to abraxane using H-scan imaging: Preliminary results in a small animal model of breast cancer

Abstract

H-scan is a new ultrasound (US) technique that images the relative size of acoustic scatterers. This modality relies on matching a model of pulse-echo formation to the mathematics of a class of Gaussian-weighted Hermite polynomials (GH). Parallel convolution filters using the second (GH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) and eighth (GH <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sub> ) components are applied to the radio frequency (RF) US data to capture the low and high frequency signal components, respectively. The relative strength from each convolution is color-coded and imaged. The purpose of this study was to evaluate the potential of H-scan imaging for characterizing tumor tissue and any early response to systemic anticancer treatment. Preliminary in vivo H-scan imaging studies were performed using an animal model of breast cancer. B-scan and H-scan imaging was performed before and after injection of an anticancer drug (albumin-bound paclitaxel) to assess any early tumor response and cellular disruption. Imaging was repeated along the same tumor cross-section every 30 min for at least 2 h. The results show that there was a significant overall change in the mean H-scan image intensity (compared to baseline measurements) at 120 min (29.2 ± 0.8%, p = 0.001). At this same time point, there was also a decrease in the B-scan image intensity (18.4 ± 3.0%, p = 0.03). Preliminary examples presented suggest that H-scan imaging is a promising tissue characterization modality. Further, H-scan may provide prognostic value during monitoring of the early tumor response (or lack thereof) to anticancer treatment.