Applications of Quantitative Perfusion and Permeability in the Brain

Abstract The brain is arguably the most common application area of perfusion Magnetic Resonance Imaging (MRI), and all main techniques (arterial spin labeling [ASL], dynamic contrast-enhanced [DCE], dynamic susceptibility contrast [DSC]) have been proposed for clinical applications. This chapter discusses the three most common clinical application areas of perfusion MRI in the brain: (I) Cerebrovascular diseases are a heterogeneous group of disorders that affect the blood vessels of the brain. These are subdivided into ischemic and hemorrhagic. Since they affect the blood vessels of the brain, it stands to reason that perfusion mapping may be valuable in the diagnosis and treatment of cerebrovascular disease. This chapter will focus specifically on acute ischemic stroke and chronic cerebrovascular ischemia; (II) Gliomas, specifically glioblastomas (GBMs), are the most common type of brain cancer in adults, and result in a median survival rate of 15–16 months. In the last 50 years, the survival rate of GBMs has improved slowly compared to other types of cancer owing to the aggressive and difficult-to-treat nature of these tumors. Quantitative perfusion MRI parameters may serve as important imaging biomarkers for the evaluation of new drugs as well as improving the current standard of care. (III) Dementia covers a range of progressive, chronic neurodegenerative diseases, including Alzheimer's disease (AD), frontotemporal dementia (FTD), vascular dementia, and dementia with Lewy bodies. While the precise mechanisms of neurodegeneration caused by the accumulation of these neurotoxic proteins are not well understood, it is well known that these increases are accompanied by associated decreases in metabolism. These changes in metabolism are mirrored by local changes in cerebral perfusion, which can be measured by DSC or ASL, and which may act as a surrogate for metabolic change or potentially an early predictor.