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Wall Contrast Enhancement of Thrombosed Intracranial Aneurysms at 7T MRI - AJNR News Digest
July-August 2020
ADULT BRAIN

Wall Contrast Enhancement of Thrombosed Intracranial Aneurysms at 7T MRI

Wrede picture

Karsten H. Wrede

Sato picture

Taku Sato

Since 2009, our ultra-high-field 7T MRI has allowed us in vivo visualization of the cerebral vascular microstructures. We are paying special attention to cerebrovascular diseases such as cerebral aneurysms, Moyamoya angiopathy, arteriovenous malformations, and cavernous angiomas.1-4 We were able to demonstrate the triple-layered microstructure of the aneurysm walls in giant intracranial aneurysms by 7T MRI.2 Our study on Moyamoya angiopathy demonstrated excellent delineation of deeply seated collateral network pathways using TOF-MRA, comparable or superior to DSA.3

One current research focus is thrombosed intracranial aneurysms. Vessel wall imaging for intracranial aneurysms using gadolinium-enhanced MRI has become more and more popular as it might serve as a biomarker for aneurysm instability. However, in current imaging techniques, wall enhancement is visualized as a single rim due to insufficient spatial resolution, and microstructures cannot be discriminated in vivo. This study aimed to assess the wall microstructure of the thrombosed intracranial aneurysm wall with gadolinium-enhanced 7T MRI.

Histopathologic findings were correlated with 7T MRI to identify the gadolinium-enhancing microstructures. All thrombosed intracranial aneurysms showed partial or complete rim enhancement. Partial or complete inner wall enhancement correlated with neovascularization of the intima and the adjacent thrombus. Additional partial or complete outer wall enhancement can be explained by the formation of vasa vasorum in the adventitia. The double-rim enhancement correlated with perifocal edema and histologic findings suggestive of wall instability. Two distinct aneurysm wall microstructures responsible for gadolinium enhancement not depictable at a lower spatial resolution can be visualized in vivo using gadolinium-enhanced 7T MRI.

References

  1. Dammann P, Wrede K, Zhu Y, et al. Correlation of the venous angioarchitecture of multiple cerebral cavernous malformations with familial or sporadic disease: a susceptibility-weighted imaging study with 7-Tesla MRI. J Neurosurg 2017;126:570–77, 10.3171/2016.2.JNS152322
  2. Matsushige T, Chen B, Ringelstein A, et al. Giant intracranial aneurysms at 7T MRI. AJNR Am J Neuroradiol 2016;37:636–41, 10.3174/ajnr.A4569
  3. Matsushige T, Kraemer M, Sato T, et al. Visualization and classification of deeply seated collateral networks in Moyamoya angiopathy with 7T MRI. AJNR Am J Neuroradiol 2018;39:1248–54, 10.3174/ajnr.A5700
  4. Wrede KH, Dammann P, Mönninghoff C, et al. Non-enhanced MR imaging of cerebral aneurysms: 7 Tesla versus 1.5 Tesla. PLoS One 2014;9:e84562, 10.1371/journal.pone.0084562

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