Lowerison, Matthew R.

Performing 3D ultrasound imaging at a real-time volume rate (e.g., >20 Hz) is a challenging task. While 2D array transducers remain the most practical approach for real-time 3D imaging, the large number of transducer elements (e.g., several thousand) that are necessary to cover an effective 3D field-of-view impose a fundamental constraint on imaging speed. Although solutions such as multiplexing and specialized transducers, including sparse arrays and row-column-addressing arrays, have been developed to address this limitation, they inevitably compromise imaging quality (e.g., SNR, resolution) in favor of speed. Coupled with the high equipment cost of 2D arrays, these compromises hinder the widespread adoption of 3D ultrasound imaging technologies in clinical settings. In this presentation, we introduce an innovative transducer clip-on device comprising a water-immersible, fast-tilting electromechanical acoustic reflector and a redirecting reflector to enable real-time 3D ultrasound imaging using common 1D array transducers. We will first introduce the principles underlying our novel technique, followed by validation studies incorporating simulation and experimental data. We will also demonstrate the feasibility of using the clip-on device to achieve a high 3D imaging volume rate that is suitable for advanced imaging modes such as shear wave elastography, blood flow imaging, and super-resolution ultrasound localization microscopy.

Objective . To develop a 3D shear wave elastography (SWE) technique using a 2D row column addressing (RCA) array, with either external vibration or acoustic radiation force (ARF) as the shear wave source. Impact Statement . The proposed method paves the way for clinical translation of 3D SWE based on the 2D RCA, providing a low-cost and high volume rate solution that is compatible with existing clinical systems. Introduction . SWE is an established ultrasound imaging modality that provides a direct and quantitative assessment of tissue stiffness, which is significant for a wide range of clinical applications including cancer and liver fibrosis. SWE requires high frame rate imaging for robust shear wave tracking. Due to the technical challenges associated with high volume rate imaging in 3D, current SWE techniques are typically confined to 2D. Advancing SWE from 2D to 3D is significant because of the heterogeneous nature of tissue, which demands 3D imaging for accurate and comprehensive evaluation. Methods . A 3D SWE method using a RCA array was developed with a volume rate up to 2000 Hz. The performance of the proposed method was systematically evaluated on tissue-mimicking elasticity phantoms and in an in vivo case study. Results . 3D shear wave motion induced by either external vibration or ARF was successfully detected with the proposed method. Robust 3D shear wave speed maps were reconstructed for phantoms and in vivo . Conclusion . The high volume rate 3D imaging provided by the 2D RCA array provides a robust and practical solution for 3D SWE with a clear pathway for future clinical translation.

RXRA is an endothelial- and early stage–predominant therapeutic target for treating anthracycline-induced cardiotoxicity.

ABSTRACT The adult zebrafish is an emerging vertebrate model for studying human cardiomyopathies; however, whether the simple zebrafish heart can model different subtypes of cardiomyopathies, such as dilated cardiomyopathy (DCM), remains elusive. Here, we generated and characterized an inherited DCM model in adult zebrafish and used this model to search for therapeutic strategies. We employed transcription activator-like effector nuclease (TALEN) genome editing technology to generate frame-shift mutants for the zebrafish ortholog of human BCL2-associated athanogene 3 (BAG3), an established DCM-causative gene. As in mammals, the zebrafish bag3 homozygous mutant (bag3e2/e2) exhibited aberrant proteostasis, as indicated by impaired autophagy flux and elevated ubiquitinated protein aggregation. Through comprehensive phenotyping analysis of the mutant, we identified phenotypic traits that resembled DCM phenotypes in mammals, including cardiac chamber enlargement, reduced ejection fraction characterized by increased end-systolic volume/body weight (ESV/BW), and reduced contractile myofibril activation kinetics. Nonbiased transcriptome analysis identified the hyperactivation of the mechanistic target of rapamycin (mTOR) signaling in bag3e2/e2 mutant hearts. Further genetic studies showed that mtorxu015/+, an mTOR haploinsufficiency mutant, repaired abnormal proteostasis, improved cardiac function and rescued the survival of the bag3e2/e2 mutant. This study established the bag3e2/e2 mutant as a DCM model in adult zebrafish and suggested mtor as a candidate therapeutic target gene for BAG3 cardiomyopathy.

Abstract INTRODUCTION AND OBJECTIVES: Patient responses to cancer immunotherapy such as checkpoint inhibitor drugs vary greatly between patients and there remains no biomarker to predict sensitivity to these drugs. We describe a patient derived xenograft (PDX) avatar system that predicts cancer immunotherapy responses in the context of tumor heterogeneity within 8-10 days. This avatar model preserves the original tumor microenvironment and tumor infiltrating lymphocytes (TILs) at a high tumor take rate for evaluation of various immunotherapy drugs. This prediction model also involves tumor infiltrating lymphocyte isolation and primary cell generation for confirming the immunotherapy response in vitro. This PDX avatar platform generates rapid actionable information and readily identifies patients that would maximally benefit from checkpoint inhibitor therapies in a phenotype-based manner. METHODS: Tissue from patients that underwent a nephrectomy for RCC or metastasectomy were engrafted into the chorioallantoic membrane of avian embryos with a portion used for TIL isolation and primary cell generation. PD-1 and PD-L1 checkpoint inhibitors were intravenously injected and high frequency ultrasound imaging and immunophenotyping was used to quantitate changes in tumor volume, vascularity, and TIL expansion in all treatment groups. Isolated TILs were expanded and co-cultured with respective primary cells to confirm and examine immunotherapy response at a molecular level. RESULTS: Patient PDXs demonstrated heterogeneous responses to immunotherapy that relates to presence and expansion of TILs after checkpoint inhibitor injection. Patient #1 demonstrated the greatest response with a >50% reduction in tumor volume and 4X expansion of T-cells over 8 days of treatment. Patient #2 demonstrated intratumoral heterogeneities in terms of tumor volume change after checkpoint inhibitors treatment despite TIL expansion in all treatment groups. Patient #3 showed no response that correlated to lack of TILs in the PDX. In vitro expansion of TILs and co-culture with primary cell line demonstrated a specific immune response via INF-gamma release and changes in immunomodulatory molecules. CONCLUSIONS: This PDX system preserves TILs and permits rapid large scale prediction of tumor specimens to various systemic therapy agents such as checkpoint inhibitors without the need for humanized models. This avatar system is a useful tool to rapidly predict and examine response to checkpoint inhibitors on a per-patient basis to improve the assignment of cancer immunotherapies to specific RCC patients. Citation Format: Mario Cepeda, Matthew Lowerison, Cindy Liu, Yarolslav Fedyshyn, Vidhu Joshi, Paras Shah, John Cheville, R. Houston Thompson, Boorjian Stephen, Bradley Leibovich, Haidong Dong, Hon S. Leong. Rapid patient derived xenograft avatars that consider tumor heterogeneity for prediction of cancer immunotherapy responses in metastatic renal cell carcinoma patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-155.

During contrast-enhanced ultrasound (CEUS) imaging of tumor microvascular perfusion, nearby arteriole enhancement can be a dominant feature of the wash-in kinetics that obscures the perfusion characteristics of the capillary bed. This presentation demonstrates that statistical wash-in curves generated using our compound CEUS speckle model1 exhibit two distinct phases corresponding to “fast-flow” and “slow-flow” enhancement that can be detected by fitting a linear combination of two monoexponential functions with different time constants. CEUS cine loops were acquired from a patient-derived xenograft model of renal cell carcinoma, where fresh tumor fragments were engrafted into the chicken embryo chorioallantoic membrane. Subharmonic CEUS images were acquired at 18 MHz using a destruction-replenishment protocol. Enhancement of manually segmented tumor cross-sections was analyzed offline in MATLAB. The CEUS cine loops from this xenograft model frequently exhibited in-plane arteriole enhancement. The two-phase fit discriminated a slow-flow component in 26.6% of time-intensity wash-in curves and 62.9% of the statistical wash-in curves, leading to a decrease in estimated tumor blood volume by 22.1% and 24.7%, respectively, compared to a simple monoexponential fit. These results suggest that conventional CEUS processing may frequently overestimate capillary blood volume. 1M.R. Lowerison et al., Med. Phys. 44, 99-111 (2017).