====== Arteriovenous malformation nidus ====== {{rss>https://pubmed.ncbi.nlm.nih.gov/rss/search/1jo74WIY5-k8p6ZfmpxtYWO0DuVamwxL6tLqEeRCcn41bJis96/?limit=15&utm_campaign=pubmed-2&fc=20231114062651}} ---- ---- The distinguishing feature of an AVM is that shunting occurs through a collection of tortuous dysmorphic vessels, referred to as a nidus ---- A [[arteriovenous malformation]] nidus diameter < 3 cm was the independent predictor of a 2-year seizure-free outcome, whereas underlying [[epilepsy]] was the factor against a 2-year [[seizure]]-free outcome ((Khumtong R, Katawatee K, Amornpojnimman T, Riabroi K, Sungkaro K, Korathanakhun P. Predictors of seizure control in patients with cerebral arteriovenous malformation. Epilepsy Behav. 2022 Feb 2;128:108575. doi: 10.1016/j.yebeh.2022.108575. Epub ahead of print. PMID: 35123239.)). ---- A study aimed to explore the potential risk factors of [[recurrence]] in angiographically obliterated AVMs treated with [[endovascular embolization]]. This study reviewed AVMs treated with [[embolization]] only in a prospective [[multicenter]] - registry from August 2011 to December 2021, and ultimately included 92 AVMs who had achieved angiographic [[obliteration]]. Recurrence was assessed by follow-up [[digital subtraction angiography]] (DSA) or [[magnetic resonance imaging]] (MRI). [[Hazard ratio]]s (HRs) with 95% [[confidence interval]]s were calculated using [[Cox model]]. Nineteen AVMs exhibited recurrence on follow-up imaging. The recurrence rates after complete [[obliteration]] at 6 months, 1 year, and 2 years were 4.35%, 9.78%, and 13.0%, respectively. Multivariate Cox regression analysis identified diffuse [[nidus]] ([[Cerebral proliferative angiopathy]])(HR 3.208, 95% CI 1.030-9.997, p=0.044) as an independent risk factor for recurrence. Kaplan-Meier analysis confirmed a higher cumulative risk of recurrence with diffuse nidus (log-rank, p=0.016). Further, in the exploratory analysis of the effect of embolization timing after AVM rupture on recurrence after the complete obliteration, embolization within 7 days of the hemorrhage was found as an independent risk factor (HR 4.797, 95% CI 1.379-16.689, p=0.014). Kaplan-Meier analysis confirmed that embolization within 7 days of the hemorrhage was associated with a higher cumulative risk of recurrence in ruptured AVMs (log-rank, p<0.0001). This study highlights the significance of diffuse nidus as an independent risk factor for recurrence after complete embolization of AVMs. In addition, they identified a potential recurrent risk associated with early [[embolization]] in ruptured AVMs ((Hao Q, Zhang H, Han H, Jin H, Ma L, Li R, Li Z, Li A, Yuan K, Zhu Q, Wang K, Li R, Lin F, Wang C, Zhang Y, Zhang H, Zhao Y, Jin W, Gao D, Guo G, Yan D, Pu J, Kang S, Ye X, Li Y, Sun S, Wang H, Chen Y, Chen X, Zhao Y; Registry of Multimodality Treatment for Brain Arteriovenous Malformation in Mainland China (MATCH). Recurrence of Cerebral Arteriovenous Malformation Following Complete Obliteration Through Endovascular Embolization. Transl Stroke Res. 2023 Nov 13. doi: 10.1007/s12975-023-01215-8. Epub ahead of print. PMID: 37957446.)). ---- __This study makes a valuable contribution to the understanding of AVM recurrence after endovascular embolization. The prospective design, clear outcome measures, and identification of independent risk factors enhance the study's credibility. However, the findings should be interpreted cautiously, considering the limitations in sample size, generalizability, and the need for additional research to elucidate certain associations.__ ---- To assess the [[sensitivity]] and [[specificity]] of [[arteriovenous malformation]] (AVM) [[nidus]] component identification and quantification using unsupervised [[machine learning]] [[algorithm]], and to evaluate the association between intervening nidal [[brain parenchyma]] and [[radiation]]-induced changes (RICs) after [[stereotactic radiosurgery]] (SRS). Fully [[automated segmentation]] via unsupervised classification with [[fuzzy c-means clustering]] was used to analyze [[AVM]] [[nidus]] on [[T2]]-weighted [[magnetic resonance imaging]]. The proportions of vasculature, brain parenchyma, and [[cerebrospinal fluid]] (CSF) were quantified. This was compared to [[manual segmentation]]. Association between brain parenchyma component and RIC development was assessed. The proposed algorithm was applied to 39 [[unruptured]] [[AVM]]s. This included 17 female and 22 male patients with a median age of 27 years. The median percentages of the constituents were as follows: vasculature (31.3%), brain parenchyma (48.4%), and CSF (16.8%). RICs were identified in 17 (43.6%) of 39 patients. Compared to manual segmentation, the automated algorithm was able to achieve a Dice similarity index of 79.5% (sensitivity=73.5% and specificity=85.5%). RICs were associated with higher proportions of intervening nidal brain parenchyma (52.0% vs. 45.3%, p=0.015). Obliteration was not associated with a higher proportions of nidal vasculature (36.0% vs. 31.2%, p=0.152). The automated segmentation algorithm was able to achieve the classification of AVM nidus components with relative accuracy. Higher proportions of intervening nidal brain parenchyma were associated with RICs ((Lee CC, Yang HC, Lin CJ, Chen CJ, Wu HM, Shiau CY, Guo WY, Hung-Chi Pan D, Liu KD, Chung WY, Peng SJ. Intervening nidal brain parenchyma and risk of radiation-induced changes after radiosurgery for brain arteriovenous malformation: a study using unsupervised machine learning algorithm. World Neurosurg. 2019 Jan 21. pii: S1878-8750(19)30103-2. doi: 10.1016/j.wneu.2018.12.220. [Epub ahead of print] PubMed PMID: 30677586. )).