Article
Detection of mural iron accumulation (MIA) in cerebral aneurysms as a marker for instability – A prospective comparative analysis of T2*-weighted and susceptibility-weighted imaging
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Authors
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Marguerite Müller
- Institut für Diagnostische und Interventionelle Neuroradiologie, RWTH Aachen, Germany
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Omid Nikoubashman
- Institut für Diagnostische und Interventionelle Neuroradiologie, RWTH Aachen, Germany
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Martin Wiesmann
- Institut für Diagnostische und Interventionelle Neuroradiologie, RWTH Aachen, Germany
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Arno Reich
- Neurologische Klinik, RWTH Aachen, Germany
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Hans Clusmann
- Klinik für Neurochirurgie, RWTH Aachen, Germany
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Gerrit Alexander Schubert
- Klinik für Neurochirurgie, RWTH Aachen, Germany
| Published: | June 8, 2016 |
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Outline
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Objective: Mural iron accumulation (MIA) within the aneurysm is thought to indicate instability and impending rupture, implying an important role for rupture risk stratification. To detect MIA, previous investigations had to resort to ultra-high field MR imaging (≥7T). However, the applicability of these results to routine clinical practice is limited. It is the purpose of this investigation to analyse the determinability of iron deposition within the aneurysm wall using T2*-weighted and susceptibility-weighted imaging (SWI) sequences in a customary 3T MRI scanner (Magnetom Prisma, Siemens Healthcare).
Method: A total of 19 patients (mean age 51.5 ± 15.6yrs) with 27 previously untreated cerebral aneurysms (mean diameter 6.1 ± 6.9mm) were prospectively identified and scanned using a standardized protocol for T2*-weighted and susceptibility-weighted imaging (SWI) sequences at 3T. MR images were reviewed by two experienced neuroradiologists and a reference standard for statistical analysis was obtained in a consensus reading. Scans were analyzed for iron-detection and possible confounding factors such as adjacent or distant sulcal hemosiderin deposition, location, proximity to bone and sinuses, as well as aneurysm size.
Results: Overall determinability of MIA was significantly higher for SWI than for T2*-weighted images (48.5% vs. 13.9%, p<0.01). Distorting hemosiderin deposition was only observed in very few cases (3% vs. 2.8%, ns). For SWI sequences, interpretation tended to improve further in larger aneurysms (≥5mm, 69,2% vs. 31.6%; p=0.07) and aneurysms located distant to pneumatized compartments (i.e. sphenoid sinus) such as MCA or basilar artery aneurysms vs. Acom or proximal ICA aneurysms (63,2% vs. 28.6%; p=0.08). In aneurysms ≥5mm and distant to air-filled compartments determinability of MIA increased to 100%. Proximity of bone did not affect evaluation quality in either modality (T2*, SWI).
Conclusions: Detection of MIA as an important marker for instability in cerebral aneurysms is feasible in routine clinical practice. In our prospective cohort, SWI at 3T featured superior determinability for MIA when compared to T2*-weighted images. Even outside experimental, ultra-high field scanning facilities, SWI can achieve excellent assessability (particularly in aneurysm of 5mm and larger, located distant to sinuses), supporting its role for aneurysm analysis.
