Abstract
Mild traumatic brain injury (mTBI) is a silent epidemic worldwide that causes suffering from the long-term effects on behavior changes and the peripheral organs system, especially in the pediatric population. The current diagnostic assessment for mTBI has not covered those traces of the disease that do not appear when using CT-scan and MRI imaging techniques. Moreover, shades of evidence showed that TBI is associated with cardiac dysfunction, but the pathophysiology is still unclear. The combination of photoacoustic imaging (PAI) and high-resolution ultrasound (US) makes it possible to assess the oxygen saturation (sO2) of organs and to measure cardiac function accurately. The objective of our work was to longitudinal assess and monitor brain-to-heart interactions with PAI and US imaging for measuring sO2 and cardiac function in a juvenile mTBI model. The mTBI was induced by a single impact of closed-head injury. We introduced PAI to assess transient brain hypoxia. The two-and four-dimensional ultrasound (2DUS and 4DUS) detected progressively cardiac diastolic dysfunction with preserved ejection fraction. During dobutamine stress test the animals exhibited cardiac systolic dysfunction and impaired oxygen consumption of the myocardium. The correlations between brain hypoxia and cardiac dysfunction enlightened brain-heart interactions after mTBI. Moreover, animal status post-mTBI correlated with behavior changes in learning and motor performance defects in the long term. In conclusion, PAI, 2D, and 4D imaging techniques revealed that mTBI in the juvenile model leads to transient brain hypoxia, eliciting cardiac dysfunction and behavior alterations in the long term. This study gives a new promise to improve early assessment for mTBI with non-invasive, non-ionizing radiation and a rapid approach.