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Published on: June 3, 2021
Altered flow territories after extracranial-intracranial bypass surgery
Jeroen Hendrikse1, Albert van der Zwan, Lino M P Ramos
1Department of Radiology, University Medical Center, Utrecht, The Netherlands. j.hendrikse@azu.nl
Insights
High-flow extracranial-intracranial bypass surgery restores cerebral blood flow after internal carotid artery occlusion. Postoperative imaging confirms adequate perfusion despite smaller bypass flow territories.
Area of Science:
- Neurosurgery
- Vascular Surgery
- Neuroradiology
Background:
- High-flow extracranial-intracranial (EC-IC) bypass surgery is performed to prevent stroke in internal carotid artery (ICA) occlusion and augment cerebral perfusion.
- Postoperative monitoring shows lower bypass flow than contralateral ICA, raising questions about tissue perfusion versus flow territory size.
Purpose of the Study:
- To investigate the cause of reduced postoperative flow in EC-IC bypasses.
- To assess regional cerebral blood flow and flow territory volume after EC-IC bypass.
Main Methods:
- Seven patients with ICA occlusion undergoing high-flow EC-IC bypass were studied.
- Arterial spin labeling perfusion MRI was used to measure cerebral blood flow.
- Selective arterial spin labeling MRI mapped flow territories of the bypass, contralateral ICA, and posterior circulation.
Main Results:
- Cerebral blood flow was comparable between the bypass hemisphere, contralateral hemisphere, and healthy controls.
- A 15% reduction in flow territory volume was observed on the side of the EC-IC bypass compared to the contralateral side.
Conclusions:
- Selective arterial spin labeling MRI is feasible for clinical follow-up of EC-IC bypass patients.
- This technique provides information on both flow territories and regional cerebral blood flow levels post-surgery.
Objective:
To prevent stroke after carotid sacrifice and to augment cerebral perfusion in patients with internal carotid artery (ICA) occlusion, high-flow extracranial-intracranial (EC-IC) bypass operations are performed. Although the function and efficacy of the bypass is monitored during surgery, the postoperative flow through the bypass is significantly lower than the flow in the contralateral ICA. Thus far, it is unknown whether decreased bypass flow is caused by a low tissue perfusion or by a relatively small flow territory.
Methods:
Seven patients, four with an atherosclerotic ICA occlusion and three with a giant aneurysm of the ICA, were investigated; each underwent a high-flow EC-IC bypass and permanent occlusion of the ICA. Cerebral blood flow was measured with arterial spin labeling perfusion magnetic resonance imaging. Separate flow territory mapping of the EC-IC bypass, contralateral ICA, and posterior circulation was performed with selective arterial spin labeling magnetic resonance imaging.
Results:
No significant difference was found in cerebral blood flow between the hemisphere ipsilateral to the EC-IC bypass (70.9 +/- 11.3 ml/min/100 g tissue), contralateral to the EC-IC bypass (71.9 +/- 14.3 ml/min/100 g tissue), and comparable findings in 50 healthy control participants (69.1 +/- 17.5 ml/min/100 g tissue). Paired analysis of the individual flow territories demonstrated a 15% volume reduction (P = 0.018) in flow territory of the EC-IC bypass compared with the contralateral side.
Conclusion:
In the present study, we demonstrate the feasibility of selective arterial spin labeling magnetic resonance imaging for clinical follow-up of patients after high-flow EC/IC bypass surgery, providing both information on flow territories and the level of regional cerebral blood flow.
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