Assessment of Global Hemodynamic Alterations in Patients after Subarachnoid Hemorrhage Using Perfusion MRI

Perfusion MRI (P-MRI) in subarachnoid hemorrhage (SAH) was found sensitive to detect focal disturbances of cerebral hemodynamics. Though vasospasm may be the major reason for disturbances of cerebral perfusion, also other factors, e.g. increase of intracranial pressure, brain edema etc., alter cerebral hemodynamics. The depiction and analysis of possible global changes of cerebral perfusion in patients after SAH was the aim of this study. 16 patients between day 6–11 after acute SAH who were suspected of suffering from vasospasm due to increased flow velocities in transcranial Doppler sonography were examined with P-MRI. After calculation of standardized time to peak (stdTTP) parameter maps the results were compared to age-matched controls using an adapted morphometrical evaluation procedure, which was designed to assess common cerebral perfusion alterations in the tested SAH group. Volumes showing decreased stdTTP values could be related to proximal vessel segments also exhibiting increased flow velocities in transcranial Doppler sonography. Volumes suffering from hemodynamic stress, as defined by an increase of stdTTP values, were detected in the periventricular parenchyma and the borderzones in both hemispheres. The results are suggestive of global perfusion disturbances, which mainly affect the distal cerebral vessel segments, additionally to the main effects of vasospasm, in patients after SAH.