Magnetic Resonance Imaging quantitation of superior sagittal sinus flow: Correlation to cerebral blood flow measured by xenon-enhanced computed tomography

We compared measurements of venous blood flow velocity in the superior sagittal sinus (SSS) obtained by magnetic resonance imaging (MRI) and quantitative measurements of cerebral blood flow (CBF) obtained by xenon- enhanced CT, in neurosurgical patients and normal volunteers, to assess the clinical usefulness of MRI for determination of CBF. Flow measurements were obtained in 15 neurosurgical patients and 3 normal volunteers. SSS velocimetry was performed using the direct bolus imaging technique with a 1.5-tesla MRI system near the point of lambda on a sagittal MR image. Quantitative CBF was measured by xenon-enhanced CT and correlated with SSS flow velocity. We also examined the effect of surgical evacuation of a hematoma or cranioplasty in 3 patients, mannitol in 5 patients and acetazolamide in 4 patients by performing SSS velocimetry. The peak SSS flow velocity during the entire cardiac cycle was 27.2 +/- 6.3 cm sec(-1) (mean +/- SD) in normal volunteers and 23.5 +/- 8.9 cm sec(-1) in patients. The SSS flow velocity increased after surgery. Mean SSS peak flow velocity increased by 24% and 48% at 10 min after administration of mannitol and acetazolamide, respectively. SSS peak flow velocity showed significant linear correlations with both cerebral cortical (r=0.74) and hemispheric flows (r=0.73). Our results suggest that SSS flow velocity reflects CBF and that MRI assessment of SSS flow provides a simple method for assessing and monitoring global changes in cerebral hemodynamics.