Abstract 124: Quantifying Intracranial Aneurysm Wall Permeability for Risk Assessment Using Dynamic Contrast Enhanced MRI: A Pilot Study
Introduction: Aneurysmal subarachnoid hemorrhage is the leading cause of non-traumatic hemorrhagic strokes. We propose a technique for assessing intracranial aneurysm (IA) rupture risk by quantifying wall permeability with dynamic contrast enhanced (DCE) MRI. We determine the correlation between IA wall permeability and established metrics of rupture risk.
Methods: Twenty aneurysms in 19 patients were imaged with DCE-MRI and wall permeability parameters (kTrans and vL) were quantified adjacent to the aneurysm wall using Tofts’ permeability model (Figure 1). The DCE time course (1a), the AIF (red), and observed signal, S(t) (white) are measured. The permeability signal, P(t) (c) is modeled and fitted using Toft’s equation allowing quantitation of kTrans (d), shown superimposed on the DCE image. Three risk paradigms based on size indices (size, aspect ratio) and clinical criteria (progression to rupture, symptomatic presentation, dome irregularities) were used to split aneurysms into high and low-risk groups. Mean kTrans and vL were calculated in each risk group for each paradigm and compared using a student’s t-test. In addition, correlation analysis was used to compare kTrans and vL against size and aspect ratio.
Results: In all IAs, there was pronounced increase in wall permeability compared to a paired healthy normal vessel (kTrans - 0.0922 vs. 0.0096 min-1, p<0.001; vL - 11 vs. 0.30 %, p<0.001). KTrans is significantly larger in high versus low risk aneurysms when risk is based on size (0.13 min-1 vs 0.06 min-1, p=0.01) and clinical endpoints (0.12 min-1 vs 0.05 min-1, p <0.01), but vL did not differ significantly. KTrans correlated strongly with size (p=0.005, r2=0.57) but vL did not (p=0.08, r2=0.19).
Conclusions: Increased wall-permeability in intracranial aneurysms correlates with rupture risk and may indicate instability, growth, or remodeling. Further studies with histological correlation on harvested IA wall specimens are necessary.
Author Disclosures: P. Vakil: None. S.A. Ansari: None. C.S. Eddleman: None. B. Bendok: None. H.H. Batjer: None. T.J. Carroll: None.
- © 2014 by American Heart Association, Inc.