Perfusion-weighted MRI to evaluate cerebral autoregulation in aneurysmal subarachnoid haemorrhage

Area of Science:

• Neuroimaging
• Cerebrovascular Physiology
• Radiology

Background:

• Aneurysmal subarachnoid hemorrhage (SAH) can lead to delayed cerebral ischemia due to cerebral vasospasm (CVS).
• Evaluating autoregulatory mechanisms in SAH is crucial for understanding and managing this condition.
• Perfusion-weighted magnetic resonance imaging (PW-MRI) offers a method to assess cerebral blood flow and volume.

Purpose of the Study:

• To evaluate autoregulatory mechanisms in different vascular territories within the first week after SAH.
• To correlate regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) with the degree of CVS.
• To assess the functionality of vascular autoregulation using PW-MRI.

Main Methods:

• PW-MRI and digital subtraction angiography were performed in 51 SAH patients approximately 5 days post-SAH.
• rCBF and rCBV were analyzed in anterior cerebral artery (ACA), middle cerebral artery (MCA), and basal ganglia territories.
• Correlations between rCBF, rCBV, and CVS were statistically analyzed.

Main Results:

• CVS was detected in 22 of 51 patients.
• Decreased rCBV and rCBF were observed with increasing CVS severity across all territories.
• Severe CVS in ACA territories was associated with significantly lower rCBF compared to controls and patients without CVS.
• Basal ganglia showed significantly higher rCBF and rCBV in controls compared to SAH patients without or with moderate CVS.

Conclusions:

• PW-MRI demonstrated a simultaneous decrease in rCBF and rCBV in SAH patients.
• The lack of rCBV increase to maintain rCBF in territories with CVS indicates dysfunctional vascular autoregulation.
• Microvascular vasospasms, evidenced by decreased rCBF and rCBV, were most prominent in the basal ganglia, even in SAH patients without overt CVS.