Introduction: Perihematomal hypoperfusion in acute intracerebral hemorrhage (ICH) has been demonstrated using CT perfusion. Although blood pressure (BP) reduction does not appear to impact perihematomal Cerebral Blood Flow (CBF), measurements using contrast are limited to a single time point. It has also been shown that up to 41% of ICH patients develop subacute diffusion-weighted imaging (DWI) lesions on MRI. Arterial Spin Labelling (ASL) is an magnetic resonance imaging (MRI) technique that allows measurement of CBF without a contrast agent, making it suitable for serial measurements. We assessed CBF in ICH patients using ASL and tested the hypothesis that perihematoma perfusion is related to BP.
Methods: Patients with CT scan confirmed ICH were prospectively recruited within 6 hours of symptom onset. Acute systolic BP (SBP) targets were randomly assigned as part of an ongoing trial. The SBP target remained blinded for this analysis. Patients were assessed with ASL at 48 hours post ICH. The perihematoma region was defined using co-registered susceptibility weighted images to delineate the hematoma border. Relative CBF (rCBF) was calculated as a ratio of the ipsilateral to contralateral ASL measurements.
Results: Perfusion was measured in 6 ICH patients, none of whom had DWI lesions, 55.38 (43.72, 59.75) hours after onset. Median 48 hour hematoma volume was 23.40 (18.10, 99.90) ml. Mean±SD SBP at 48 hours was 140.20 ± 10.64 mmHg. Mean perihematomal rCBF was 0.95±0.37. Mean hemispheric rCBF was 0.95 ± 0.17. Perihematomal and hemispheric CBF was not lower in the side of the hematoma (p>0.583). Hematoma size was unrelated to rCBF (perihematomal R=0.039, 95% CI [-0.880, 0.959], p=0.682; hemispheric R=0.00, 95% CI [-0.005, 0.006], p=0.932). Systolic BP at the time of the scan, difference between baseline SBP and SBP at the time of the scan, and time spent with SBP <140 mmHg were all not associated with perihematomal or hemispheric rCBF (p>0.170).
Conclusion: It is feasible to measure perihematoma and hemispheric perfusion in ICH patients using ASL, which may be useful for serial CBF assessment, particularly in patients with MRI evidence of ischemia.