Aneurysm wall enhancement in black blood MRI correlates with aneurysm size. Black blood MRI could serve as an objective criterion of aneurysm stability in near future

Gadolinium-enhanced intracranial aneurysm wall imaging and risk of aneurysm growth and rupture: a multicentre longitudinal cohort study

OBJECTIVES

In patients with an unruptured intracranial aneurysm, gadolinium enhancement of the aneurysm wall is associated with growth and rupture. However, most previous studies did not have a longitudinal design and did not adjust for aneurysm size, which is the main predictor of aneurysm instability and the most important determinant of wall enhancement. We investigated whether aneurysm wall enhancement predicts aneurysm growth and rupture during follow-up and whether the predictive value was independent of aneurysm size.

MATERIALS AND METHODS

In this multicentre longitudinal cohort study, individual patient data were obtained from twelve international cohorts. Inclusion criteria were as follows: 18 years or older with ≥ 1 untreated unruptured intracranial aneurysm < 15 mm; gadolinium-enhanced aneurysm wall imaging and MRA at baseline; and MRA or rupture during follow-up. Patients were included between November 2012 and November 2019. We calculated crude hazard ratios with 95%CI of aneurysm wall enhancement for growth (≥ 1 mm increase) or rupture and adjusted for aneurysm size.

RESULTS

In 455 patients (mean age (SD), 60 (13) years; 323 (71%) women) with 559 aneurysms, growth or rupture occurred in 13/194 (6.7%) aneurysms with wall enhancement and in 9/365 (2.5%) aneurysms without enhancement (crude hazard ratio 3.1 [95%CI: 1.3-7.4], adjusted hazard ratio 1.4 [95%CI: 0.5-3.7]) with a median follow-up duration of 1.2 years.

CONCLUSIONS

Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not independent of aneurysm size.

CLINICAL RELEVANCE STATEMENT

Gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, since it appears to have no additional value to conventional predictors.

KEY POINTS

• Although aneurysm wall enhancement is associated with aneurysm instability in cross-sectional studies, it remains unknown whether it predicts risk of aneurysm growth or rupture in longitudinal studies. • Gadolinium enhancement of the aneurysm wall predicts aneurysm growth or rupture during short-term follow-up, but not when adjusting for aneurysm size. • While gadolinium-enhanced aneurysm wall imaging is not recommended for short-term prediction of growth and rupture, it may hold potential for aneurysms smaller than 7 mm.

Systemic immune-inflammation index is associated with aneurysmal wall enhancement in unruptured intracranial fusiform aneurysms

Introduction

Inflammation plays a key role in the progression of intracranial aneurysms. Aneurysmal wall enhancement (AWE) correlates well with inflammatory processes in the aneurysmal wall. Understanding the potential associations between blood inflammatory indices and AWE may aid in the further understanding of intracranial aneurysm pathophysiology.

Methods

We retrospectively reviewed 122 patients with intracranial fusiform aneurysms (IFAs) who underwent both high-resolution magnetic resonance imaging and blood laboratory tests. AWE was defined as a contrast ratio of the signal intensity of the aneurysmal wall to that of the pituitary stalk ≥ 0.90. The systemic immune-inflammation (SII) index (neutrophils × platelets/lymphocytes) was calculated from laboratory data and dichotomized based on whether or not the IFA had AWE. Aneurysmal symptoms were defined as sentinel headache or oculomotor nerve palsy. Multivariable logistic regression and receiver operating characteristic curve analyses were performed to determine how well the SII index was able to predict AWE and aneurysmal symptoms. Spearman's correlation coefficients were used to explore the potential associations between variables.

Results

This study included 95 patients, of whom 24 (25.3%) presented with AWE. After adjusting for baseline differences in neutrophil to lymphocyte ratios, leukocytes, and neutrophils in the multivariable logistic regression analysis, smoking history (P = 0.002), aneurysmal symptoms (P = 0.047), maximum diameter (P = 0.048), and SII index (P = 0.022) all predicted AWE. The SII index (P = 0.038) was the only independent predictor of aneurysmal symptoms. The receiver operating characteristic curve analysis revealed that the SII index was able to accurately distinguish IFAs with AWE (area under the curve = 0.746) and aneurysmal symptoms (area under the curve = 0.739).

Discussion

An early elevation in the SII index can independently predict AWE in IFAs and is a potential new biomarker for predicting IFA instability.

Vessel wall imaging and quantitative flow assessment in arteriovenous malformations: A feasibility study

INTRODUCTION

Cerebral arteriovenous malformations (AVMs) carry a rupture rate of 2-3% per year. Several architectural factors may influence rupture rate, and a recently theorized model of AVMs describes the influence of vessel wall inflammation. A novel imaging modality, vessel wall imaging (VWI), has been developed to view inflammatory processes in vessel wall foci but has not yet been examined in AVMs, which is the aim of this study.

METHODS

This retrospective review studies prospectively collected data on patients with ruptured and unruptured AVMs between 2019 and 2021. Inclusion criteria included adult patients (≥18 years) with radiographically diagnosed AVM who underwent VWI. Charts were reviewed for medical history, clinical presentation, hospital course, discharge condition, and follow-up. Angioarchitectural features, blood flow, and VWI were compared in patients with and without hemorrhagic patients.

RESULTS

Nine patients underwent VWI, mean age 37.7 ± 9.9 years. Four presented with hemorrhage (44.4%). Seven (77.7%) received glue embolization and 6 (66.7%) underwent surgical resection. All patients (4/4) with a history of hypertension presented with hemorrhage (p = 0.0027). Size and Spetzler-Martin grade were not associated with hemorrhage (p = 0.47, p = 0.59). Net AVM flow was higher in patients presenting with hemorrhage, although nonsignificant (p = 0.19). With VWI, 3 (75%) hemorrhagic AVMs showed visible nidus and draining veins, and all three demonstrated positive post-contrast wall enhancement in at least one of their draining veins; conversely, of fivenonhemorrhagic AVMs, only 2 (40%) demonstrated post-contrast wall enhancement in any draining vein (p = 0.090).

CONCLUSION

This pilot study successfully demonstrated capture of venous walls in AVMs using VWI. In this study, draining vein enhancement occurred more often in hemorrhagic AVM and in those with higher venous volumetric flow.

Intracranial aneurysm wall (in)stability-current state of knowledge and clinical perspectives

Intracranial aneurysm (IA), a local outpouching of cerebral arteries, is present in 3 to 5% of the population. Once formed, an IA can remain stable, grow, or rupture. Determining the evolution of IAs is almost impossible. Rupture of an IA leads to subarachnoid hemorrhage and affects mostly young people with heavy consequences in terms of death, disabilities, and socioeconomic burden. Even if the large majority of IAs will never rupture, it is critical to determine which IA might be at risk of rupture. IA (in)stability is dependent on the composition of its wall and on its ability to repair. The biology of the IA wall is complex and not completely understood. Nowadays, the risk of rupture of an IA is estimated in clinics by using scores based on the characteristics of the IA itself and on the anamnesis of the patient. Classification and prediction using these scores are not satisfying and decisions whether a patient should be observed or treated need to be better informed by more reliable biomarkers. In the present review, the effects of known risk factors for rupture, as well as the effects of biomechanical forces on the IA wall composition, will be summarized. Moreover, recent advances in high-resolution vessel wall magnetic resonance imaging, which are promising tools to discriminate between stable and unstable IAs, will be described. Common data elements recently defined to improve IA disease knowledge and disease management will be presented. Finally, recent findings in genetics will be introduced and future directions in the field of IA will be exposed.

An Image-Based Workflow for Objective Vessel Wall Enhancement Quantification in Intracranial Aneurysms

BACKGROUND

VWE in contrast-enhanced magnetic resonance imaging (MRI) is a potential biomarker for the evaluation of IA. The common practice to identify IAs with VWE is mainly based on a visual inspection of MR images, which is subject to errors and inconsistencies. Here, we develop and validate a tool for the visualization, quantification and objective identification of regions with VWE.

METHODS

N = 41 3D T1-MRI and 3D TOF-MRA IA images from 38 patients were obtained and co-registered. A contrast-enhanced MRI was normalized by the enhancement intensity of the pituitary stalk and signal intensities were mapped onto the surface of IA models generated from segmented MRA. N = 30 IAs were used to identify the optimal signal intensity value to distinguish the enhancing and non-enhancing regions (marked by an experienced neuroradiologist). The remaining IAs (n = 11) were used to validate the threshold. We tested if the enhancement area ratio (EAR-ratio of the enhancing area to the IA surface-area) could identify high risk aneurysms as identified by the ISUIA clinical score.

RESULTS

A normalized intensity of 0.276 was the optimal threshold to delineate enhancing regions, with a validation accuracy of 81.7%. In comparing the overlap between the identified enhancement regions against those marked by the neuroradiologist, our method had a dice coefficient of 71.1%. An EAR of 23% was able to discriminate high-risk cases with an AUC of 0.7.

CONCLUSIONS

We developed and validated a pipeline for the visualization and objective identification of VWE regions that could potentially help evaluation of IAs become more reliable and consistent.

[Unruptured asymptomatic brain aneurysms: modern approaches to the choice of surgical method and treatment outcomes]

BACKGROUND

In recent years, significant attention has been paid to preventive vascular neurosurgery. Treatment of unruptured asymptomatic brain aneurysms is one of the sections of this surgery.

OBJECTIVE

To evaluate treatment outcomes in patients with unruptured asymptomatic brain aneurysms who underwent treatment chosen on the basis of criteria adopted at the Burdenko Neurosurgery Center.

MATERIAL AND METHODS

There were 2814 unruptured asymptomatic brain aneurysms in 2334 patients for the period from 1995 to 2019.

RESULTS

Microsurgical operations for unruptured asymptomatic brain aneurysms were performed in 64.9% of cases, endovascular procedures - in 35.1% of patients. Endovascular operations were usually performed for ICA aneurysms and posterior aneurysms of circle of Willis. Microsurgical operations were mainly performed in patients with aneurysms of anterior and middle cerebral arteries. Favorable outcomes (GOS grade V-IV) were obtained in most patients (98.3%). Incidence of severe complications was similar in both groups, mortality rate was 0.3% and 0.4%, respectively.

CONCLUSION

Currently, there is a tendency towards annual increase in the number of surgeries for unruptured brain aneurysms. Anatomical and morphological characteristics of aneurysm should be considered to achieve favorable clinical results. At the same time, comprehensive analysis of each case and identification of individual risk factors will eliminate serious complications of surgical treatment.

Wall enhancement segmentation for intracranial aneurysm

We present a tool for automatic segmentation of wall enhancement of intracranial aneurysms in black blood MRI. The results of the automatic segmentation with several configurations is compared to manual expert segmentations. While the manual segmentation includes some voxels of lower intensity not present in the automatic segmentation, overall the volume of the automatic segmentation is higher.