Ultrasound localization microscopy of renal tumor xenografts in chicken embryo is correlated to hypoxia

Abstract

Ultrasound localization microscopy (ULM) permits the reconstruction of super-resolved microvascular images at clinically relevant penetration depths, which can be potentially leveraged to provide noninvasive quantitative measures of tissue hemodynamics and hypoxic status. We demonstrate that ULM microbubble data processing methods, applied to images acquired with a Verasonics Vantage 256 system, can provide a non-invasive imaging surrogate biomarker of tissue oxygenation status. This technique was applied to evaluate the microvascular structure, vascular perfusion, and hypoxia of a renal cell carcinoma xenograft model grown in the chorioallantoic membrane of chicken embryos. Histological microvascular density was significantly correlated to ULM measures of intervessel distance (R = −0.92, CI 95 = [−0.99,−0.42], p = 0.01). The Distance Metric, a measure of vascular tortuosity, was found to be significantly correlated to hypoxyprobe quantifications (R = 0.86, CI 95 = [0.17, 0.99], p = 0.03). ULM, by providing non-invasive in vivo microvascular structural information, has the potential to be a crucial clinical imaging modality for the diagnosis and therapy monitoring of solid tumors.

The Chicken Chorioallantoic Membrane Tumor Assay as a Relevant In Vivo Model to Study the Impact of Hypoxia on Tumor Progression and Metastasis

“…Due to the high metabolic demand and inadequate vasculature of such tumors, hypoxia is also a dynamic state that fluctuates according to the rapid cancer cell proliferation rate and the generation of new blood vessels within the tumor [ 48 , 57 ]. Previous reports have shown the presence of hypoxia in HT-1080 human fibrosarcoma and Renca mouse renal adenocarcinoma CAM xenografts [ 37 , 58 ]. Here we demonstrate that hypoxia is present within multiple cancer cell line-derived xenografts, as well as patient-derived ccRCC xenografts, when grown on the CAM.…”

Super-Resolution Imaging with Ultrasound for Visualization of the Renal Microvasculature in Rats Before and After Renal Ischemia: A Pilot Study

“…Other ultrasound techniques and imaging modalities are competing with the SR imaging setup presented in this paper. Ultrasound plane-wave techniques are commonly used to obtain SR images at a higher framerate [ 8 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. To facilitate a faster implementation of SR imaging in the clinic, we used focused beam transmission which is an established technology in commercial ultrasound platforms.…”

“…The healthy microvasculature of rodent organs and tissues has been visualized with SR imaging [ 8 , 9 , 10 , 11 , 12 , 13 ]. SR imaging can also visualize and quantify the pathological microvascular patterns in rodent and chicken embryo tumors [ 14 , 15 , 16 ] and the later stages of acute kidney injury in mice [ 17 ]. With a rich and anatomically distinctive vasculature [ 18 ], the kidneys are attractive organs for SR imaging.…”

Short Acquisition Time Super-Resolution Ultrasound Microvessel Imaging via Microbubble Separation

“…Ultrasound in-phase quadrature (IQ) data were acquired separately from the longitudinal view of the flow channel at four different flow rates (1.89 ml/min, 2.83 ml/min, 3.77 ml/min and 4.71 ml/min, corresponding to average flow speed of 10 mm/s, 15 mm/s, 20 mm/s and 25 mm/s, respectively, and corresponding to peak flow speed of 20 mm/s, 30 mm/s, 40 mm/s and 50 mm/s, respectively assuming parabolic flow profile) using a Verasonics Vantage ultrasound system (Verasonics Inc.,Kirkland, WA, USA) and a GE 9 L linear array probe (GE Healthcare, Ex ovo CAM preparation. We followed the CAM preparation and tumor engraftment procedures outlined in 28,29 , with slight modification to facilitate co-registered acoustic-optical imaging. Fertilized chicken eggs were obtained from Hoover's Hatchery (Rudd, IA) and placed into a turning humidified incubator (Digital Sportsman Cabinet Incubator 1502, GQF).…”