High-Resolution Ultrasound in Research of Mouse Orthotopic Glioma and Ultrasound-Guided Cell Implant

The purpose is to evaluate the feasibility of imaging mouse brain with high resolution ultrasound (HiRes US), and generation of mouse brain tumor (glioma) model under HiRes US guided implantation of glioma cells. Normal mouse brain was imaged with 30 MHz HiRes US in six pups and ten adult nude mice. Glioma model was developed by injecting human glioma cells (5 × 105), U-87MG-luc, under HiRes US guidance, in three pups and five adult mice. Bioluminescence imaging, magnetic resonance imaging, and HiRes US were used for in vivo tumor imaging. In addition, brain imaging ex vivo with HiRes US were also performed in three tumor bearing and five normal brains. The brain parenchyma was seen as a homogeneous low echo on HiRes US without locoregional echo differences. An inverted U shaped linear echo structure (fissure) differentiated the telencephalon from the diencephalon. Bilaterally budding structure at the base of the skull represented the trigeminal nerve. The inserted needle, used to implant the glioma cells, was seen as a high linear echogenic reflection. Brain tumor on ex vivo HiRes US was well demarcated, homogeneous and hyperechoic compared to the surrounding healthy brain. In conclusion, imaging the brain with HiRes US in small animal model like mouse is possible and convenient. Real-time guiding is possible to perform any intervention from tumor implantation to percutaneous therapeutic procedures. Ex vivo, HiRes US is extremely useful to study the detailed anatomical features.