Hemodynamic Analysis Related Research And Clinical Application For Cerebral Aneurysms

CHAPTER ONE Assessment of anterior cerebral artery architectural impact for ACo A aneurysm initiation based on patient-specific CFD analysisObjective: This study aims to identify anatomic,morphological and hemodynamic independent risk factors for ACo A(anterior communicating artery)aneurysm occurrence,using computational fluid dynamics(CFD)simulations based on patient-specific models before and after Aco A aneurysm removal.Methods: Records of patients and 3D angiography data of 15 consecutive patients harboring 15 Aco A aneurysms were retrospectively reviewed.CFD analyses were carried out using 3D-DSA images.Reconstruction of 3D pre-aneurysmal geometric models were performed and then the results of these simulations were postprocessed and visualized with CFD software.Geometric and hemodynamic parameters were collected for comparison and evaluation.Results: Fifteen ACo A aneurysms from 15 patients(10 females,5 males,age 60.7±14 years)were used in this study.The overall prevalence of symmetric(SG),asymmetric(AS),dominant(DG)and aplastic(AP)A1 was 13.3%(2/15),40%(6/15),26.7%(4/15),and 20%(3/15),respectively.Mean WSS of aplastic group was significantly higher compared with the other groups(5.95±1.7,5.35±0.3,5.78±0.6 and 8.05±0.9;P<0.05).Absolute mean A1 artery flow of the aneurysm side was similar between the symmetric,asymmetrical and dominant group(410.2±88 m L/min,438.4±73 m L/min and 440.3±101 m L/min)(P=0.53),but significantly higher in the aplastic group(528.1 m L/min)(P<0.05).The aneurysm-side A1-A2 angles showed no significant differences among the 4 groups,99.3?,102.7?,101.8? and 103.4?for the SG,AS,DG and AP group,respectively(P=0.35).The total mean A1-A2 angle on the IA side were significantly lower than the contralateral A1-A2 angle(101.9? versus 120.3?;P<0.05).Regression analysis demonstrated that higher WSS were significantly associated with larger A1-2 ratio(R=0.52;P<0.05).Conclusions: ACo A aneurysm is a high WSS and OSI pathology.Increased flow impingement and anatomic vasculature structure plays a triggering role in Aco A aneurysm occurence that may be exploited as a monitor.This will require further studies with larger numbers of ACo A cases and more precise and appropriate experimental data.CHAPTER TWO Stent-assisted coiling of intracranial C6 segment aneurysms: long-term follow-up researchObjective: To evaluate the efficacy of stent-assisted coiling(SAC)used in the treatment for C6 segment aneurysms(C6 aneurysms)of the internal carotid artery(ICA)by a detailed long-term follow-up of a large patient cohort.Methods: We retrospectively analyzed 88 consecutive patients with C6 aneurysms between January 2007 and January 2016 in our center.Angiographic results were evaluated with the modified Raymond grading system,and clinical outcomes were evaluated with the m RS scale.Primary endpoints included major aneurysm recurrence and poor clinical outcome through at least 18 months’ follow-up.Results: We enrolled 88 patients harboring 99 C6 aneurysms that were treated with coiling,of which 76 cases were treated with SAC.Coiling procedures were successful in all 88 patients.Overall,complications occurred in 8 patients(9.1%).There was no procedure-related mortality in this series.67(76.1%)had immediate aneurysm occlusion at the end of the procedure.After a clinical follow-up time of 28.7 months,85 patients(95.5%)attained favorable clinical outcomes(m RS scores of 0-2).Conclusions: The study indicates that SAC treatment is a safe and effective therapeutic alternative in ruptured and unruptured C6 aneurysms;the hemodynamic factors of C6 segement influence long-term treatment effectiveness.CHAPTER THREE Association of wall shear stress with intracranial aneurysm rupture: systematic review and meta-analysisObjective: To evaluate the relationship between wall shear stress(WSS)magnitude and cerebral aneurysm rupture and provide new insight into the disparate computational fluid dynamics(CFD)findings concerning the role of WSS in intracranial aneurysm(IA)rupture.Methods: A systematic electronic database(Pub Med,Medline,Springer,and EBSCO)search was conducted for all accessible published articles up to July 1,2016,with no restriction on the publication year.Abstracts,full-text manuscripts,and the reference lists of retrieved articles were analyzed.Random effects meta-analysis was used to pool the low WSS rates across studies.Results: Twenty-two studies containing CFD data on 1257 patients with aneurysms were included in the analysis.A significantly higher rate of low WSS(0–1.5 Pa)was found in ruptured aneurysms(odds ratio [OR] 2.17;95% confidence interval [CI],1.73–2.62).The pooled analyses across 14 studies with low WSS showed significantly lower mean WSS(0.64 versus 1.4 Pa)(P=0.037)in the ruptured group.Conclusions: This meta-analysis provides evidence that decreased local WSS may be an important predictive parameter of IA rupture.CHAPTER FOUR Efficacy of flow-diverting devices for cerebral aneurysms: systematic review and meta-analysisObjective: To evaluate the efficacy of flow-diverting devices(FDDs)used in the treatment for intracranial aneurysms(IAs),we performed a meta-analysis of published literature on FDDs.Methods: A systematic electronic database search was conducted using MEDLINE,Pub Med,Springer,and EBSCO for all accessible articles on FDDs published until 2016.Abstracts,full-text manuscripts,and the reference lists of retrieved articles were analyzed.Random effects meta-analysis was used to pool the occlusion rate outcomes across studies.Results: Sixty studies were included,which involved retrospectively collected data on 3125 patients.The overall complete occlusion rate was 82.5%(95% CI,78.8%–86%)across studies.FDD treatment showed significantly higher complete occlusion rate than conventional endovascular treatment(OR 3.13;95% CI,2.11–4.65).The use of FDDs was associated with an overall complication rate of 17.0%(95% CI,13.6%–20.5%)and a low mortality rate of 2.8%(95% CI,1.2%–4.4%).Conclusions: FDDs have high occlusion rates and low complication rates in the management of IAs.Additional studies on well-designed,multicenter,randomized controlled trials will be required to validate the findings of the present study and to identify the best therapeutic strategy for IAs depending on their size,location,and rupture status.CHAPTER FIVE Dynamic contrast-enhanced magnetic resonance angiography for the localization of spinal dural arteriovenous fistulas at 3TObjective: This study was undertaken to evaluate the accuracy of dynamic contrastenhanced magnetic resonance angiography(DCE-MRA)in the precise location and demonstration of fistulous points in spinal dural arteriovenous fistulas(SDAVFs).Methods: Fifteen patients(14 men,1 woman;age range: 40–78 years;mean: 55.5 years)harboring SDAVF who underwent preoperative DCE-MRA and spinal digital subtraction angiography(DSA)between January 2012 and June 2015 were evaluated retrospectively.Two reviewers independently evaluated the level and side of the arteriovenous fistula and feeding artery on 3T DCE-MRA and DSA images.The accuracy of DCE-MRA was assessed by comparing its findings with those from DSA and surgery in each case.Results: All 15 patients underwent DCE-MRA and DSA.DSA was unsuccessful in two patients due to technical difficulties.All cases were explored surgically,guided by the DCE-MRA.The origin of the fistulas and feeding arteries were accurately shown by DCE-MRA in 11 of the 15 patients.In 15 out of 20 fistulas(75%),both readers agreed on the location on DCE-MRA images,and the coefficient of the interobserver agreement was 0.67(95% CI,0.16–0.87).In 13 of 16 shunts(75%),the DCE-MRA consensus findings and DSA findings coincided.The intermodality agreement was 0.77(95% CI,0.35–0.92).Conclusions: Our DCE-MRA studies benefited from the use of a high-field 3T MR imaging unit and reliably detected and localized the SDAVF and feeding arteries.As experience with this technique grows,it may be possible to replace DSA with DCE-MRA if surgery is the planned treatment.