Correlation Between Thrombus Signal Intensity and Aneurysm Wall Thickness in Partially Thrombosed Intracranial Aneurysms Using 7T Magnetization-Prepared Rapid Acquisition Gradient Echo Magnetic Resonance Imaging.

Taku Sato,Ulrich Sure,Stefan Maderwald,Philipp Dammann,Karsten H Wrede,Toshinori Matsushige,Bixia Chen,Mark E Ladd,Harald H Quick,Oliver Gembruch,Michael Forsting,Ramazan Jabbarli,Andreas Junker

doi:10.3389/fneur.2022.758126

Abstract

ObjectiveThe objective of this study is to investigate the relationship between the thrombus signal intensity and aneurysm wall thickness in partially thrombosed intracranial aneurysms in vivo with magnetization-prepared rapid acquisition gradient echo (MPRAGE) taken using 7T magnetic resonance imaging (MRI) and correlate the findings to wall instability.MethodsSixteen partially thrombosed intracranial aneurysms were evaluated using a 7T whole-body MR system with nonenhanced MPRAGE. To normalize the thrombus signal intensity, its highest signal intensity was compared to that of the anterior corpus callosum of the same subject, and the signal intensity ratio was calculated. The correlation between the thrombus signal intensity ratio and the thickness of the aneurysm wall was analyzed. Furthermore, aneurysmal histopathological specimens from six tissue samples were compared with radiological findings to detect any correlation.ResultsThe mean thrombus signal intensity ratio was 0.57 (standard error of the mean [SEM] 0.06, range 0.25–1.01). The mean thickness of the aneurysm wall was 1.25 (SEM 0.08, range 0.84–1.55) mm. The thrombus signal intensity ratio significantly correlated with the aneurysm wall thickness (p < 0.01). The aneurysm walls with the high thrombus signal intensity ratio were significantly thicker. In histopathological examinations, three patients with a hypointense thrombus had fewer macrophages infiltrating the thrombus and a thin degenerated aneurysmal wall. In contrast, three patients with a hyperintense thrombus had abundant macrophages infiltrating the thrombus.ConclusionThe thrombus signal intensity ratio in partially thrombosed intracranial aneurysms correlated with aneurysm wall thickness and histologic features, indicating wall instability.

Highlights

Aneurysmal subarachnoid hemorrhage is a heavy health burden with estimated annual incidence ranges of 6–8 patients per 1,00,000 with high morbidity rates [1]
Previous studies have suggested that the pathophysiology of thrombosed intracranial aneurysms differs from that of nonthrombosed aneurysms [4]
Inclusion criteria were [1] patients with a partially thrombosed intracranial aneurysm diagnosed by digital subtraction angiography and conventional computed tomography or 3T magnetic resonance imaging (MRI), [2] ≥18 years old, and [3] able to provide informed consent

Summary

Introduction

Aneurysmal subarachnoid hemorrhage is a heavy health burden with estimated annual incidence ranges of 6–8 patients per 1,00,000 with high morbidity rates [1]. Different diagnostic markers for the instability of the cerebral aneurysm walls were reported [2]. Ngoepe et al mentioned that it is not clear whether thrombosis formation in the aneurysm stabilizes the aneurysm or makes it more likely to rupture [3]. Most thrombosed aneurysms are large (12–24 mm) or giant (>25 mm) and are complex and associated with a high risk of complications with treatment [5]. The overall prevalence of thrombosed intracranial aneurysms remains unknown; an autopsy series reported 9% of all intracranial aneurysms [6]. Because thrombosed aneurysms are large, surgical treatment is preferred because they are prone to rupture. If the aneurysm was stabilized, treatment may not be needed

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Results

Conclusion