Association between PET-MR imaging measures of blood-brain barrier leakage and immune cell activation in acute intracerebral hemorrhage

Intracerebral hemorrhage is a severe form of stroke. Secondary injury involves a cascade of pathophysiological changes thought to begin with microglial activation and result in blood-brain barrier(BBB) breakdown and edema formation. In this study, patients underwent dynamic contrast-enhanced MRI and [11C](R)-PK11195 PET, which measure BBB leakage and binding to the translocator protein 18kDa (TSPO) expressed on activated microglia, respectively. BBB leakage and TSPO binding were elevated in the edema. Mean co-localisation of BBB leakage and TSPO binding was 5.6%; drugs targeting inflammation may cross the BBB into 0-28% of target tissue. Modified Rankin Scale scores negatively correlated with BBB leakage.