Diffusion- and perfusion-weighted imaging in vasospasm after subarachnoid hemorrhage

Area of Science:

• Neuroradiology
• Cerebrovascular Imaging
• Medical Diagnostics

Background:

• Subarachnoid hemorrhage (SAH) necessitates improved methods for assessing cerebral perfusion and detecting ischemic injury.
• Vasospasm following SAH poses a significant risk for secondary ischemic complications.
• Current diagnostic tools may not fully capture the extent of hemodynamic compromise in SAH patients.

Purpose of the Study:

• To evaluate the utility of combined diffusion-weighted (DW) and hemodynamically weighted (HW) MRI in identifying tissue ischemia and early ischemic injury in SAH patients with vasospasm.
• To investigate the relationship between hemodynamic abnormalities and diffusion-weighted imaging findings in the context of vasospasm.

Main Methods:

• Utilized combined DW and HW MRI techniques in patients with SAH and varying degrees of vasospasm.
• Assessed cerebral blood volume (rCBV), cerebral blood flow (rCBF), and mean transit time (tMTT) using contrast bolus passage analysis.
• Hypothesized that HW imaging abnormalities would exceed DW imaging abnormalities in symptomatic vasospasm.

Main Results:

• Symptomatic vasospasm patients exhibited small DWI lesions surrounded by extensive areas of reduced rCBF and increased tMTT.
• Hemodynamic abnormalities on MRI correlated with the territories of angiographic vasospasm or their watershed areas.
• Neurological deficits in patients corresponded to significantly larger areas of abnormal tMTT compared to DWI abnormalities.

Conclusions:

• Combined DW/HW MRI effectively detects extensive hemodynamic alterations in symptomatic vasospasm, encompassing early ischemic foci.
• This advanced MRI technique shows promise as a valuable clinical tool for managing SAH patients.
• Further research is warranted to fully establish its role in patient care.