Non-invasive ultrasound detection of cerebrovascular changes in a mouse model of TBI

carotid arteries of mice exposed to a controlled cortical impact. Focusing on the first harmonics of the reflected waves, the impedance phase was increased ipsilaterally in impacted mice compared to shams whereas the magnitude of the impedance was unchanged. In contrast, PI was reduced bilaterally. Interestingly, PI and the first harmonic magnitude of input impedance in the carotid artery were correlated on the contralateral but not ipsilateral side. We investigated the use of these metrics to classify mice as sham or TBI, finding an area under the ROC curve ipsilaterally of 0.792 (CI: 0.648 – 0.936) for correct classification with first harmonic impedance magnitude and phase as predictors and 0.716 (CI: 0.553 – 0.879) using carotid artery PI and diameter as predictors. Overall, the findings support the use of wave reflection analysis as a more specific measure of vascular changes following TBI and motivate the translation of this approach for monitoring vascular changes in humans affected by TBI.