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Magnetic resonance angiographic assessment after extracranial-intracranial bypass surgery
S S Praharaj1, A Coulthard, A Gholkar
1Department of Surgery (Neurosurgery), Medical School, University of Newcastle upon Tyne, UK.
Insights
Magnetic resonance angiography (MRA) effectively assesses extracranial-intracranial (EC-IC) bypass patency, offering insights into flow dynamics. This technique complements conventional cerebral angiography for evaluating cerebral circulation augmentation.
Area of Science:
- Neurosurgery
- Vascular Surgery
- Diagnostic Imaging
Background:
- Extracranial-intracranial (EC-IC) bypass surgery augments cerebral blood flow.
- Postoperative bypass patency is crucial for successful outcomes.
- Conventional cerebral angiography is the standard for assessment.
Observation:
- Six patients with EC-IC bypasses underwent assessment using magnetic resonance angiography (MRA).
- Indications included intracavernous carotid aneurysms, skull base tumors, and internal carotid artery occlusion.
- Three patients also had conventional cerebral angiography for comparison.
Findings:
- MRA demonstrated reasonable correlation with conventional cerebral angiography in assessing bypass patency.
- Conventional angiography showed superior detail for small vessels.
- MRA provided additional information on relative flow contribution and direction using presaturation pulses.
Implications:
- MRA is a valuable non-invasive tool for evaluating EC-IC bypass patency.
- MRA offers functional flow information not available with conventional angiography.
- These findings support MRA's role in the postoperative management of EC-IC bypass patients.
Abstract:
Extracranial-intracranial (EC-IC) bypass operation may be performed to augment the distal cerebral circulation. The bypass patency is usually assessed postoperatively with conventional cerebral angiography. Six patients are reported in whom the bypass patency was assessed using magnetic resonance angiography (MRA): Two had intracavernous carotid aneurysms, three had base of skull tumours encompassing the internal carotid artery, and one had occlusion of the right internal carotid artery with poor collateral reserve as confirmed by an acetazolamide stimulation test. Postoperative conventional cerebral angiography was also obtained in three patients for comparison. The MRA correlated reasonably well with conventional cerebral angiography in showing bypass patency, although conventional cerebral angiography was superior in demonstrating small vessels; MRA has the added advantage of showing the relative flow contribution and flow direction under physiological conditions by using targeted presaturation pulses.