Abstract 2470: Comparison of H-scan ultrasound and diffusion-weighted magnetic resonance imaging of head and neck cancer undergoing neoadjuvant chemotherapy
Authors: Tai Haowei , Margolis Ryan , Li Junjie , Trinh Brian , Song Jane , Hoyt Kenneth 
Published: June 2022

Abstract
Introduction: The use of ultrasound (US) for tumor tissue characterization remains an exciting prospect. The purpose of this research project was to introduce a 3-dimensional (3-D) H-scan US imaging system, which links information in the backscattered US signals to various-sized tissue structures in volume space, and evaluate use for monitoring early response of head and neck cancer to neoadjuvant chemotherapy.
Methods: Studies were conducted using female mice (N = 20) implanted in the mammary fat pad with 1 million breast cancer cells (MDA-MB-231). Once tumors reached about 0.8 cm in size, animals were divided into three groups so that mean tumor size in each were comparable. Animals underwent H-scan US and diffusion-weighted magnetic resonance imaging (DW-MRI) at baseline and again at days 1, 3, and 7. After baseline imaging, animals were administered neoadjuvant treatment injections, namely: (1) 0.3 mg sterile saline (control), (2) 5 mg/kg of cisplatin, or (3) 25 mg/kg cisplatin. In vivo US imaging was performed using a Vevo 3100 system (FUJIFILM VisualSonics Inc) equipped with an MX201 linear array transducer. Volume acquisitions contained 400 frames of US image data spaced 50 μm apart. To generate the H-scan US images, Gaussian-weighted Hermite polynomial filters were convolved with the radiofrequency (RF) data to measure the relative strength of the backscattered US signals. In short, the lower frequency signals were assigned to a red (R) channel and the higher frequency components to a blue (B) channel. The unfiltered original RF signal was assigned to the green (G) channel to complete the RGB colormap. Animals were also imaged using a preclinical MRI scanner (BioSpec 3T, Bruker) using a DW-MRI sequence for generation of apparent diffusion coefficient (ADC) maps as a measure of intratumoral water diffusion. After the last day of imaging, animals were euthanized and tumor tissue excised for ex vivo analysis.
Results: In vivo results demonstrated that 3-D H-scan US imaging was considerably more sensitive to tumor changes after neoadjuvant treatment as compared to B-scan US. While there was no difference at baseline (p &gt; 0.60), H-scan US images from the cisplatin treated tumors exhibited increased intensity at day 7 (15.6 ± 1.9% and 17.2 ± 3.2% for low and high dosed groups, respectively; p &lt; 0.05) indicating a decrease in aggregate US scatterer size. Furthermore, longitudinal trends found using H-scan US imaging matched those from DW-MRI (p &lt; 0.05). Collectively, these observations were attributed to cancer cell nuclear condensation and apoptotic activity as confirmed by histological analysis.
Conclusions: 3-D H-scan US imaging is a promising new tool for monitoring cancer response to neoadjuvant therapy. In vivo results matched those found using DW-MRI, which is an established modality for assessing anticancer treatment using apoptosis-inducing drugs.
Citation Format: Haowei Tai, Ryan Margolis, Junjie Li, Brian Trinh, Jane Song, Kenneth Hoyt. Comparison of H-scan ultrasound and diffusion-weighted magnetic resonance imaging of head and neck cancer undergoing neoadjuvant chemotherapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 2470.