Abstract
Deuterium oxide (D2O) perfusion has been used for acquiring hemodynamic images such as tissue blood flow in early studies. As a freely diffusible tracer, D2O may also be an alternative of fluorescent tracer in discovering glymphatic system which has been demonstrated as a lymphatic-like circulation system along paravascular pathway in brain tissue. In this study, a new indirect detection strategy by 1H-MRI was used to acquire D2O perfusion images with better signal-to-noise ratio on rat brain. Then a two-compartment parallel model (2CPM) was applied to analyses of D2O perfusion to extract both blood and glymphatic dynamics simultaneously. A traditional one-compartment Tofts model (1CTM) was also applied to quantify cerebral blood flow (CBF) for comparison. The results showed that both 1CTM and 2CPM could obtain CBF maps with stable and reasonable values. Moreover, the spatial distributions of the parallel flow of 2CPM were adjacent to the locations where the paravascular pathway of cerebral-spinal fluid (CSF) lies. Therefore, according to the blood irrelevant flow values and the spatial matched mapping, we have demonstrated that using 2CPM for tracing D2O might noninvasively reveal the information of CSF-dynamics which is regulated by glymphatic system. Further investigations and applications should be conducted to connect D2O tracer analysis of 2CPM with the comprehensive water passages in rat brain.