Macrophage Imaging within Human Cerebral Aneurysm Wall Using Ferumoxytol-Enhanced MRI: Pilot StudyKeywords: aneurysm, biomarker, magnetic resonance imaging, vascular, neuropathologyInteractive Manuscript
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What is the background behind your study?
Macrophages play a critical role in cerebral aneurysm formation and progression to rupture.
What is the purpose of your study?
The purpose of this study is to determine the optimal parameters to image macrophages within human cerebral aneurysm wall using ferumoxytol-enhanced MRI.
Describe your patient group.
18 unruptured aneurysms in 12 patients were imaged using T2* GE MRI sequence.
Describe what you did.
Two protocols were utilized. Protocol A: infusion of 2.5 mg/kg of ferumoxytol and imaging at day 0 and 1. Protocol B: infusion of 5 mg/kg of ferumoxytol and imaging at day 0, 1, 3 and 5. All images were reviewed independently by two neuroradiologists to assess for ferumoxtyol-associated loss of signal intensity. Aneurysm dome tissue was harvested from patients infused with ferumoxytol and controls (no ferumoxytol) and stained with CD68 to detect macrophages and Prussian Blue to detect iron oxidize nanoparticles.
Describe your main findings.
Five out of 10 (50%) aneurysms in protocol A showed ferumoxytol-associated signal changes in aneurysm walls. Eight out of 8 (100%) aneurysms in protocol B showed clear ferumoxytol-associated MRI signal changes in the aneurysm wall at 72 hours post infusion. Aneurysm tissue harvested from patients infused with ferumoxytol stained positive for both CD68+ and Prussian Blue. Tissue harvested from control aneurysms stained positive for CD68+ but not Prussian Blue.
Describe the main limitation of this study.
This study evaluated a small sample of aneurysms.
Describe your main conclusion.
Infusion dosing of 5mg/kg of ferumoxytol and imaging at 72 hours post injection using T2* GE MRI demonstrated maximal uptake of ferumoxytol in aneurysm wall, corresponding to regions of macrophages infiltrate.
Describe the importance of your findings and how they can be used by others.
Further studies are needed to correlate the use of this technique and risk-stratification of unruptured intracranial aneurysms.
Macrophages play a critical role in cerebral aneurysm formation and progression to rupture.
The purpose of this study is to determine the optimal parameters to image macrophages within human cerebral aneurysm wall using ferumoxytol-enhanced MRI.
18 unruptured aneurysms in 12 patients were imaged using T2* GE MRI sequence.
Two protocols were utilized. Protocol A: infusion of 2.5 mg/kg of ferumoxytol and imaging at day 0 and 1. Protocol B: infusion of 5 mg/kg of ferumoxytol and imaging at day 0, 1, 3 and 5. All images were reviewed independently by two neuroradiologists to assess for ferumoxtyol-associated loss of signal intensity. Aneurysm dome tissue was harvested from patients infused with ferumoxytol and controls (no ferumoxytol) and stained with CD68 to detect macrophages and Prussian Blue to detect iron oxidize nanoparticles.
Five out of 10 (50%) aneurysms in protocol A showed ferumoxytol-associated signal changes in aneurysm walls. Eight out of 8 (100%) aneurysms in protocol B showed clear ferumoxytol-associated MRI signal changes in the aneurysm wall at 72 hours post infusion. Aneurysm tissue harvested from patients infused with ferumoxytol stained positive for both CD68+ and Prussian Blue. Tissue harvested from control aneurysms stained positive for CD68+ but not Prussian Blue.
This study evaluated a small sample of aneurysms.
Infusion dosing of 5mg/kg of ferumoxytol and imaging at 72 hours post injection using T2* GE MRI demonstrated maximal uptake of ferumoxytol in aneurysm wall, corresponding to regions of macrophages infiltrate.
Further studies are needed to correlate the use of this technique and risk-stratification of unruptured intracranial aneurysms.
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