Three-Dimensional H-Scan Ultrasound Imaging of Early Breast Cancer Response to Neoadjuvant Therapy in a Murine Model

Abstract

ObjectivesThree-dimensional (3D) H-scan is a new ultrasound (US) technique that images the relative size of acoustic scatterers. The goal of this research was to evaluate use of 3D H-scan US imaging for monitoring early breast cancer response to neoadjuvant therapy using a preclinical murine model of breast cancer.Materials and MethodsPreclinical studies were conducted using luciferase-positive breast cancer–bearing mice (n = 40). Anesthetized animals underwent US imaging at baseline before administration with an apoptosis-inducing drug or a saline control. Image data were acquired using a US scanner equipped with a volumetric transducer following either a shorter- or longer-term protocol. The later included bioluminescent imaging to quantify tumor cell viability. At termination, tumors were excised for ex vivo analysis.ResultsIn vivo results showed that 3D H-scan US imaging is considerably more sensitive to tumor changes after apoptosis-inducing drug therapy as compared with traditional B-scan US. Although there was no difference at baseline (P > 0.99), H-scan US results from treated tumors exhibited progressive decreases in image intensity (up to 62.2% by day 3) that had a significant linear correlation with cancer cell nuclear size (R2 > 0.51, P < 0.001). Results were validated by histological data and a secondary longitudinal study with survival as the primary end point.DiscussionExperimental results demonstrate that noninvasive 3D H-scan US imaging can detect an early breast tumor response to apoptosis-inducing drug therapy. Local in vivo H-scan US image intensity correlated with cancer cell nuclear size, which is one of the first observable changes of a cancer cell undergoing apoptosis and confirmed using histological techniques. Early imaging results seem to provide prognostic insight on longer-term tumor response. Overall, 3D H-scan US imaging is a promising technique that visualizes the entire tumor and detects breast cancer response at an early stage of therapy.

H‐Scan Ultrasound Monitoring of Breast Cancer Response to Chemotherapy and Validation With Diffusion‐Weighted Magnetic Resonance Imaging

“…At termination (day 10), results from our study revealed that the averaged intensity of H‐scan US image was linearly proportional to nuclear size, proliferation, and apoptotic activity, which are all intimately related histological features. This observation supports previous studies that showed a linear relationship between H‐scan US image intensity and tumor cell nuclear size measurements from registered histology images 22,26,27 . In addition to mean‐value H‐scan US measurements of the segmented tumor volumes, a textural feature referred to as homogeneity was examined.…”

“…This observation supports previous studies that showed a linear relationship between H-scan US image intensity and tumor cell nuclear size measurements from registered histology images. 22,26,27 In addition to mean-value H-scan US measurements of the segmented tumor volumes, a textural feature referred to as homogeneity was examined. Recall this image feature is helpful for quantifying the spatial relationship between local US scattering within the tumor space.…”

“…The ×25 magnification was then used to optically imaging whole tissue slides for robust histological analysis (Axio Observer 7, Carl Zeiss Microscopy, White Plains, NY). Quantitative image analysis was performed using established protocols detailed previously 22 . All parameters were summarized as percent activity of tumor cross‐sectional area.…”

“…Quantitative image analysis was performed using established protocols detailed previously. 22 All parameters were summarized as percent activity of tumor cross-sectional area.…”

Photoacoustic graphic equalization and application in characterization of red blood cell aggregates

“…Output from the matched filters is then weighted and used to colorize an image to provide local discrimination between various-sized ultrasound scatterers. Several recent reports have detailed the use of in vivo H-scan ultrasound imaging for purposes ranging from the early detection of liver steatosis [18] , [19] , [20] to monitoring cancer response to treatment [21] , [22] , [23] . We envision that the H-scan ultrasound format for tissue characterization can be extrapolated for a similar analysis of PA signals.…”