Radio-clinical grading system for transarterial AVM embolization: Tsinghua AVM grading system

Rupture risk assessment in cerebral arteriovenous malformations: an ensemble model using hemodynamic and morphological features

BACKGROUND

Cerebral arteriovenous malformation (AVM) is a cerebrovascular disorder posing a risk for intracranial hemorrhage. However, there are few reliable quantitative indices to predict hemorrhage risk accurately. This study aimed to identify potential biomarkers for hemorrhage risk by quantitatively analyzing the hemodynamic and morphological features within the AVM nidus.

METHODS

This study included three datasets comprising consecutive patients with untreated AVMs between January 2008 to December 2023. Training and test datasets were used to train and evaluate the model. An independent validation dataset of patients receiving conservative treatment was used to evaluate the model performance in predicting subsequent hemorrhage during follow-up. Hemodynamic and morphological features were quantitatively extracted based on digital subtraction angiography (DSA). Individual models using various machine learning algorithms and an ensemble model were constructed on the training dataset. Model performance was assessed using the confusion matrix-related metrics.

RESULTS

This study included 844 patients with AVMs, distributed across the training (n=597), test (n=149), and validation (n=98) datasets. Five hemodynamic and 14 morphological features were quantitatively extracted for each patient. The ensemble model, constructed based on five individual machine-learning models, achieved an area under the curve of 0.880 (0.824-0.937) on the test dataset and 0.864 (0.769-0.959) on the independent validation dataset.

CONCLUSION

Quantitative hemodynamic and morphological features extracted from DSA data serve as potential indicators for assessing the rupture risk of AVM. The ensemble model effectively integrated multidimensional features, demonstrating favorable performance in predicting subsequent rupture of AVM.

Hemodynamic changes of arteriovenous malformation and endovascular embolization

Objective: To analyze the hemodynamic changes caused by arteriovenous malformation (AVM) and AVM embolization through a meta-analysis of the existing literature. Method: Search for relevant studies on PubMed/Medline until November 7, 2023, and further screen the bibliographies of relevant studies to ensure comprehensive search. According to the PRISMA guidelines, manuscripts were selected to provide local hemodynamic information on AVM arterial feeders and drainage veins. Result: A total of 13 studies were included in the final analysis. The diameter of the supplying artery (y = 0.002x + 2.24, R2 = 0.99) and flow velocity (y = 0.09x + 54.55, R2 = 0.92) had a positive linear relationship with cerebral blood flow. The pressure difference through the small AVM nidus was higher than that in the large AVM, with values of (y = -12.23x + 101.39, R2 = 0.96). There was a negative linear correlation between the sessions of AVM embolization and blood flow (1 session: y = -150.7x + 564.97, R2 = 0.98 and 4 sessions: y = -118.81x + 750.07, R2 = 0.99). There was a positive linear relationship between the increase in arterial pressure, peri-AVM parenchymal perfusion, and the percentage of occlusion in the medium-sized AVMs. However, this correlation was a nonlinear relationship between elevated arterial pressure, peri-AVM parenchymal perfusion, and the percentage of large AVM occlusion. Conclusion: The hemodynamic changes of AVM (in the feeding arteries, compartments of AVM, and draining veins) follow a linear relationship. The impact of embolization on hemodynamics in medium and small AVMs follows a linear relationship. The impact of embolization of large AVMs on hemodynamics follows a nonlinear relationship.

Comparative efficacy and safety of N-butyl cyanoacrylate vs. Onyx in the treatment of arteriovenous malformations: a systematic review and meta-analysis

Since the first use of embolization for cerebral arteriovenous malformations (AVMs) by Luessenhop and Spence in 1960, this procedure has become a cornerstone in the multimodal treatment approach for brain AVMs. Currently, in the United States, the main embolic agents employed are n-butyl cyanoacrylate (NBCA) and Onyx (Medtronic, Minneapolis, MN). This systematic review and meta-analysis aim to compare these two agents in terms of efficacy and safety. An updated guideline for Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) was followed. The search strategy involved retrieving articles from PubMed, Scopus, and Web of Science from inception of these databases until June 27th, 2024, using specific search terms. Inclusion criteria were comparative studies of Onyx (Medtronic, Minneapolis, MN) and NBCA, peer-reviewed original studies published in full-text, and studies reporting at least one of the outcomes of interest. Statistical analysis was performed using R software version 4.3.1. After screening 3177 articles, 33 articles were assessed in full-text, and 4 studies were included in the final analysis. These studies included 374 patients, 170 (45.4%) females. There was no significant difference in complication rates between Onyx (Medtronic, Minneapolis, MN) and NBCA (risk ratio [RR]: 0.91; CI: 0.31 to 2.67, p = 0.86) with significant heterogeneity (I²=68%, p = 0.02). Technical success did not differ significantly (RR: 1.38; CI: 0.72 to 2.62, p = 0.33) with significant heterogeneity (I²=73%, p = 0.02). Mortality (RR: 1.5; CI: 0.28 to 8.08, p = 0.64; I²=16%, p = 0.31), morbidity (RR: 1.39; CI: 0.16 to 12.08, p = 0.76; I²=53%, p = 0.14), and blood loss (MD: -0.1; CI: -0.8 to 0.5, p = 0.72; I²=53%, p = 0.15) also showed no significant differences. Both NBCA and Onyx are effective and safe for embolization of cerebral AVMs, with no significant differences in complications, technical success, mortality, morbidity, and blood loss. Further research, particularly randomized controlled trials, is needed to better understand their comparative efficacy and safety.

Angiographic factors leading to hemorrhage in AVMs: A systematic review and meta-analysis

For patients with unruptured intracranial arteriovenous malformations (AVMs), the risk of a hemorrhagic event is approximately 2% to 4% annually. These events have an associated 20-50% morbidity and 10% mortality rate. An understanding of risk factors that predispose these lesions to rupture is important for optimal management. We aimed to pool a large cohort of both ruptured and unruptured AVMs from the literature with the goal of identifying angiographic risk factors that contribute to rupture. A systematic review of the literature was conducted in accordance with the PRISMA guidelines using Pubmed, Embase, Scopus, and Web of Science databases. Studies that presented patient-level data from ruptured AVMs from January 1990 to January 2022 were considered for inclusion. The initial screening of 8,304 papers resulted in a quantitative analysis of 25 papers, which identified six angiographic risk factors for AVM rupture. Characteristics that significantly increase the odds of rupture include the presence of aneurysm (OR = 1.45 [1.19, 1.77], p < 0.001, deep location (OR = 3.08 [2.56, 3.70], p < 0.001), infratentorial location (OR = 2.79 [2.08, 3.75], p < 0.001), exclusive deep venous drainage (OR = 2.50 [1.73, 3.61], p < 0.001), single venous drainage (OR = 2.97 [1.93, 4.56], p < 0.001), and nidus size less than 3 cm (OR = 2.54 [1.41, 4.57], p = 0.002). Although previous literature has provided insight into AVM rupture risk factors, obscurity still exists regarding which risk factors pose the greatest risk. We have identified six major angiographic risk factors (presence of an aneurysm, deep location, infratentorial location, exclusive deep venous drainage, single venous drainage, and nidus size less than 3 cm) that, when identified by a clinician, may help to tailor patient-specific approaches and guide clinical decisions.

Brain arteriovenous malformations of the middle cerebral artery region: image characteristics and endovascular treatment based on a new classification system

BACKGROUND

To date, few studies have investigated the use of endovascular treatment (EVT) for brain arteriovenous malformations (BAVMs) in the supplying area of the middle cerebral artery (MCA). Moreover, no suitable classification was aimed at EVT for MCA-BAVMs. Therefore, this study proposed a new classification.

METHODS

This study retrospectively collected 135 MCA‑BAVMs. They were classified into four types: Type I BAVMs located above the M1 segment; Type II BAVMs located in the region around the Sylvian fissure; and Type III BAVMs located in the supplying region of the M4 segment and subdivided into types IIIa and IIIb. The relevance of various types of MCA-BAVMs and their imaging characteristics and EVT outcomes was analyzed by ordinary one-way ANOVA, Tukey's multiple comparisons test and the chi-square test.

RESULTS

The 135 patients averaged 33.8 ± 14.7 years and included 75 females (55.6%, 75/135). Among them, 15 (11.1%, 15/135), 16 (11.9%, 16/135), 54 (40%, 54/135), and 50 (37%, 50/135) MCA-BAVMs were type I, II, IIIa and IIIb, respectively. After EVT, a good outcome was achieved in 97% of patients. Statistical analysis showed that type I BAVMs were smaller than type II and IIIb BAVMs (P value < 0.05), and type IIIb BAVMs were larger than type I and IIIa BAVMs (P value < 0.05). Deep vein involvement in type I and IIIb BAVMs was more common than in other types (P value < 0.05), and intraventricular hemorrhage (IVH) was also more common (P value < 0.05). The normal morphology in type IIIb was less than that in the other types (P value < 0.05). Type IIIa BAVMs had a higher degree than other types (P value < 0.05).

CONCLUSION

The present study demonstrated that the new classification of MCA-BAVMs can be used to evaluate imaging characteristics and EVT outcomes in different types. In addition, EVT may be a safe treatment modality for MCA‑BAVMs.