Relevance of cerebral microbleeds with leaky blood brain barrier in traumatic brain injury and protective role of interferon-gamma: A cohort study.

Objectives: Cerebral microbleeds (CMBs), which present as foci of hypointensities on T2*-weighted Magnetic Resonance Imaging (MRI) are associated with weakened vessel walls. CMBs are also a frequent finding in traumatic brain injury (TBI) in association with poor outcome. We investigated whether a combination of susceptibility weighted imaging (SWI) and dynamic contrast enhanced (DCE) MRI could accurately identify characteristics of CMBs that are most relevant to TBI. Materials and Methods: Thirty TBI patients were recruited from a neurosurgical unit. We acquired structural three-dimensional T1-weighted, T2-weighted dark fluid, SWI, and DCE-MRI images on a 3T MRI. DCE-MRI data was fitted for a linear graphic (Patlak-Gjedde) model to calculate voxel-wise volume transfer constant (Ktrans) maps. Ktrans ranges of normal-appearing brain (NAB) areas were quantified and two sub-classes of CMBs-leaky and non-leaky CMBs-were identified. Characteristics and spatial distribution of the quantified imaging metrics and the immunological blood panel results were then compared across mild versus moderate-severe TBI groups, as classified by Glasgow Coma Scale. Results: More severe TBI was associated with CMBs exhibiting leaky BBB as quantified by DCE-MRI. Higher blood levels of interferon gamma (IFN-γ) were associated with lower number of CMBs in TBI patients at more than 8 days post-TBI. Discussion: combined DCE-MRI and SWI confirmed that CMBs with leaky BBBs are more prevalent in moderate-severe TBIs compared. Higher levels of IFN-γ appeared to have been associated with fewer CMBs in the sub-acute stage of TBI.