Spinal Cord Penumbra Restoration Monitoring during Chronic Phase Using Ultrasound Localization Microscopy

Spinal cord injury (SCI) often results in a lifelong sensation loss or even paralysis. A major mechanism is no timely intervention on vasculature disruption after primary insult, which causes further expansion of infarction core and irreversible injury of penumbra zone. Techniques used foe brain penumbra including Positron Emission Tomography (PET), Diffusion-Weighted Imaging (DWI), Perfusion-Weighted Imaging (PWI), and Computed Tomography (CT) are limited in resolution. Digital subtraction angiography (DSA) and magnetic resonance angiography (MRA) are still the standard methods in clinics. Recently developed ultrasound localization microscopy (ULM) enables to map the microvasculature of small animal in deep tissue with a resolution of tens of microns. With the advantages of non-radiation, portability and super-resolution, it has become an attractive alternative for angiography and could potentially meet the needs of comprehensive intraoperative examination and prognosis tracking. In this study, ULM was performed on a standardized rat model of spinal cord compression for in vivo penumbra imaging. Basso, Beattie, Bresnahan (BBB) locomotor rating scale was applied for model validation. The high consistency between ultrasonic vascular quantification including morphology and density and animal behavioral tests was observed during penumbra development.