Abnormal cerebral blood volume in regions of contused and normal appearingbrain following traumatic brain injury using perfusion magnetic resonance imaging

Following traumatic brain injury, there may be secondary alterations in cer ebrovascular parameters leading to ischemia and further cellular damage. To assess possible subacute hemodynamic disturbances following traumatic brai n injury, we used conventional and perfusion magnetic resonance imaging (MR I) in 18 patients, on average 10 days following injury. Six of the 18 patie nts had focal contusions or edema visible on conventional MRI. These six pa tients had a significantly reduced normalized regional cerebral blood volum e (rCBV) in the regions of focal pathology compared to equivalent areas in control subjects (patients 0.47 +/- 0.20 [means +/- SD], controls 1.02 +/- 0.11, p < 0.001). In addition, four of these six patients had an increased rCBV (outside control range) in the region of normal appearing brain immedi ately surrounding the contusion. These six patients were more significantly injured and had a worse clinical outcome compared to the remaining patient s (p = 0.004, p = 0.03, respectively). There were five patients who had a r egion of reduced rCBV (outside control range) in a quadrant of normal appea ring white matter, away from any visible abnormality, who were not more sig nificantly injured than the remaining patients but went on to have a signif icantly poorer clinical outcome (p = 0.27, p = 0.01, respectively). Traumat ic brain injury is a heterogeneous insult causing a variety of pathology, n ot all of which is visible using conventional imaging methods. The current study has shown that regions of both normal appearing and contused brain ma y have an abnormal rCBV and that alterations in rCBV may play a role in det ermining the clinical outcome of patients.