Advances in imaging techniques of the blood-brain barrier and clinical application.

The blood-brain barrier (BBB) is an important structure that maintains the normal function of the central nervous system (CNS). The functional structure of BBB is closely related to diseases of CNS, including degenerative diseases, brain tumours, traumatic brain injury, stroke, etc. Imaging methods were commonly used to monitor the integrity of BBB, such as DCE-MRI, DSC-MRI, and PET, this contributes to understand the process of related diseases and develop appropriate treatment options. In recent years, many studies had shown that the MRI methods (ASL, IVIM, CEST, etc.) could evaluate blood-brain barrier function, which use endogenous contrast agents and become an increasingly great concern. Another image methods (FUS, uWB-eMPs) can open up the normal BBB, allowing macromolecular drugs across the locally opening BBB, which could be beneficial to the treatment of some brain diseases. In this review, we briefly introduce the theory of BBB imaging modalities and its clinical application.