Arterial Bypass in the Treatment of Complex Middle Cerebral Artery Aneurysms: Lessons Learned from Forty Patients

OBJECTIVE

Complex middle cerebral artery (MCA) aneurysms incorporating parent or branching vessels are often not amenable to standard microsurgical clipping or endovascular embolization treatments. We aim to discuss the treatment of such aneurysms via a combination of surgical revascularization and aneurysm exclusion based on our institutional experience.

METHODS

Thirty-four patients with complex MCA aneurysms were treated with bypass and aneurysm occlusion, 5 with surgical clipping or wrapping only, and 1 with aneurysm excision and primary reanastomosis. Bypasses included superficial temporal artery (STA)-MCA, double-barrel STA-MCA, occipital artery-MCA, and external carotid artery-MCA. After bypass, aneurysms were treated by surgical clipping, Hunterian ligation, trapping, or coil embolization.

RESULTS

The average age at diagnosis was 46 years. Of the aneurysms, 67% were large and most involved the MCA bifurcation. Most bypasses performed were STA-MCA bypasses, 12 of which were double-barrel. There were 2 wound-healing complications. All but 2 of the aneurysms treated showed complete occlusion at the last follow-up. There were 3 hemorrhagic complications, 3 graft thromboses, and 4 ischemic insults. The mean follow-up was 73 months. Of patients, 83% reported stable or improved symptoms from presentation and 73% reported a functional status (Glasgow Outcome Scale score 4 or 5) at the latest available follow-up.

CONCLUSIONS

Cerebral revascularization by bypass followed by aneurysm or parent artery occlusion is an effective treatment option for complex MCA aneurysms that cannot be safely treated by standard microsurgical or endovascular techniques. Double-barrel bypass consisting of 2 STA branches to 2 MCA branches yields adequate flow replacement in most cases.

Proximal Internal Carotid Artery Occlusion and Extracranial-Intracranial Bypass for Treatment of Fusiform and Giant Internal Carotid Artery Aneurysms

OBJECTIVE

To discuss the treatment of intracranial fusiform and giant internal carotid artery (ICA) aneurysms via revascularization based on our institutional experience.

METHODS

An institutional review board-approved retrospective analysis was performed of patients with unruptured fusiform and giant intracranial ICA aneurysms treated from November 1991 to May 2020. All patients were evaluated for extracranial-intracranial (EC-IC) bypass and ICA occlusion.

RESULTS

Thirty-eight patients were identified. Initially, patients failing preoperative balloon test occlusion were treated with superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and concurrent proximal ICA ligation. We then treated them with STA-MCA bypass, followed by staged balloon test occlusion, and, if they passed, endovascular ICA coil occlusion. We treat all surgical medically uncomplicated patients with double-barrel STA-MCA bypass and concurrent proximal ICA ligation. The mean length of follow-up was 99 months. Symptom stability or improvement was noted in 85% of patients. Bypass graft patency was 92.1%, and all surviving patients had patent bypasses at their last angiogram. Aneurysm occlusion was complete in 90.9% of patients completing proximal ICA ligation. Three patients experienced ischemic complications and 4 patients experienced hemorrhagic complications.

CONCLUSIONS

Not all fusiform intracranial ICA aneurysms require intervention, except when life-threatening rupture risk is high or symptomatic management is necessary to preserve function and quality of life. EC-IC bypass can augment the safety of proximal ICA occlusion. The rate of complete aneurysm occlusion with this treatment is 90.9%, and long-term bypass graft-related complications are rare. Perioperative stroke is a major risk, and continued evolution of treatment is required.

Abstract WP159: Examining The Utility Of 2D DSA For Carotid Stenosis Hemodynamic Pressure Analysis

Introduction: Measurement of local hemodynamic behavior is useful for assessing the pathology of carotid stenosis. In this study, we explore a novel method using two-dimensional digital subtraction angiography (2D DSA) to provide time-dependent pressure data. We performed comparative validation with computational fluid dynamics (CFD) and flow guidewire measurements as reference methods.

Methods: A silicone phantom model of a carotid stenosis was prepared, filled with physiological saline, and connected to a flow pump (Vascular Simulations, LLC Left Heart Replicator) applying pulsatile flow. The stenosis model narrowed from a diameter of 1.37 cm to 0.58 cm for a length of 0.64 cm (NASCET=40%). Iodinated contrast media was injected, and time dependent pressure profiles at four regions of interest: 2 cm proximal to the stenosis, proximal end of the stenosis, distal end of the stenosis and 2 cm distal to the stenosis were derived from contrast intensity (I) obtained from 2D DSA background-subtracted intensity plots using previously published PVEC software. A Volcano flow guidewire sensor was utilized at the same four locations to collect flow data. Pulsatile CFD flow analysis was performed to extract flow data.

Results: DSA PVEC contrast analysis allowed observation of distinct flow pulsatility. At 30fps, strong agreement of DSA contrast waveform matching CFD and guidewire flow measurements was found at the distal end of the stenosis over a period of linear contrast increase (constant dI/dt). Bland-Altman analysis was used to compare derived pressure with the reference methods over 3.5 cardiac cycles, from 5.9 s to 8.7 s after the initial injection of contrast. 2D DSA-derived pressure showed a mean departure of -10.24% (std. dev 14.65%) pressure obtained from CFD analysis, and a mean departure of -15.32% (std. dev 14.24%) from guidewire measurements for the duration.

Conclusion: A novel computational approach suggests 2D DSA can provide real-time results to approximate carotid flow from 2D DSA. We showed using this novel approach the flow data is comparable with guide wire and CFD methods. Future experiments may allow it to provide a supplementary, non-invasive means to examine local hemodynamic behavior that is relevant to the evaluation of carotid stenosis.

Reconstruction of carotid stenosis hemodynamics based on guidewire pressure data and computational modeling

A comparative analysis between intravascular guidewire-obtained and computational fluid dynamic (CFD) flow velocity and pressure data using simplified carotid stenosis models was performed. This information was used to evaluate the viability of using guidewire pressure data to provide inlet conditions for CFD flow, and to study the relationship between stenotic length and hemodynamic behavior. Carotid stenosis models differing in diameter and length were prepared and connected to a vascular pulsatile flow simulator. Time-dependent flow velocity and pressure measurements were taken by microcatheter guidewires and compared with CFD data. Guidewire and CFD-generated pressure profiles matched closely in all measurement locations. The guidewire was unable to reliably measure flow velocity at areas associated with higher CFD flow velocities (r = 0.92). CFD results showed that an increased length of stenosis generated expansive regions of elevated wall shear stress (WSS) within and distal to the stenosis. Low WSS was found immediately outside the stenosis outlet. An increase in stenotic length produced higher flow velocities with minimal lengthening of the distal high velocity flow jet due to faster dissipation of translational kinetic energy through turbulence. We found the accuracy of guidewire-obtained velocity measurements is limited to regions unaffected by disturbed flow. WSS and turbulence behavior distal to the stenosis may be important markers to evaluate the severity of atherosclerotic progression as a function of stenotic length.

Critical Angiographic and Sonographic Analysis of Intra Aneurysmal and Downstream Hemodynamic Changes After Flow Diversion

Introduction

Successful treatment of intracranial aneurysms after flow diversion (FD) is dependent on the flow modulating effect of the device. We aimed to investigate the intra-aneurysmal and parent vessel hemodynamic changes, as well as the incidence of silent emboli following treatment with various FD devices.

Methods

We evaluated the appearance of the eclipse sign in nine distinct phases of cerebral angiography before and immediately after FD placement in correlation with aneurysm occlusion. Angiographic and clinical data of consecutive procedures were analyzed retrospectively. Patients who had successful FD procedure without adjunctive coiling, visible eclipse sign on post embolization angiography, and reliable follow-up angiographic data were included in the analysis. Detailed analysis of hemodynamic data from transcranial doppler after FD was performed in selected patients, such as monitoring for silent emboli.

Results

Among all patients (N = 65) who met inclusion criteria, complete aneurysm occlusion at 12 months was achieved in 89% (58/65). Eclipse sign prior to FD was observed in 42% (27/65) with unchanged appearance in 4.6% (3/65) of the treated patients. None of these three patients achieved complete aneurysm occlusion. Among all analyzed variables, such as aneurysm size, device type used, age, and appearance of the eclipse sign pre- and post-FD, the most reliable predictor of permanent aneurysm occlusion at 12 months was earlier, prolonged, and sustained eclipse sign visibility in more than three angiographic phases in comparison to the baseline (p < 0.001). Elevation in flow velocities within the ipsilateral vascular territory was noted in 70% (9/13), and bilaterally in 54% (7/13) of the treated patients. None of the patients had silent emboli.

Conclusions

Intra-aneurysmal and parent vessel hemodynamic changes after FD can be reliably assessed by the cerebral angiography and transcranial doppler with important implications for the prediction of successful treatment.

Abstract WP10: Automated Methods Of Aneurysm Growth Detection Compared With Clinical Assessment And Follow-up

Introduction: In cases where the risk of intracranial aneurysms (IA) rupture is low or secondary to other patient health concerns, unruptured IA may be monitored through imaging. In this work, we applied different computational methods to detect IA growth and compared the results to clinical findings.

Hypothesis: We hypothesize that automated methods of IA growth detection are comparable to clinical assessment.

Methods: The study cohort consisted of 20 female patients with saccular IA diagnosed between 2005-2011 in UCLA Medical Center. 6 were located at the PcoA, 10 at the superior hypophyseal artery, and 4 at the ophthalmic artery. 8 IA were determined to be growing. Baseline IA size was 3.85±4.30 mm. For each case, initial and first follow-up CTA image studies (interval 2.50±2.75 yrs) were analyzed. Cohort follow-up continued for an average of 8.5±5.75 yrs. Automated methods to detect IA growth included maximum diameter (HMAX), surface area (SA), volume (V), and a novel 2-stage morphing approach which deforms the baseline IA surface mesh to that of the subsequent scan and yields a set of characteristics that describe the changes: dMPL, dSA, dV, and dICDD. Statistical methods used included the Mann-Whitney U test and Chi-Square Test with significance set at p <0.01, and ROC AUC analysis.

Results: The stable and growth groups did not significantly differ with respect to case details and medical history, including IA size, location, imaging interval, age, family history, stroke, hypertension, thyroid disease, cancer, and atherosclerosis. Clinically determined change in IA diameter (p=0.007, AUC=0.927), computed HMAX (p=0.0002, AUC=0.958), SA (p=0.001, AUC=0.917), V (p=0.001, AUC=0.927), and dSA (p=0.005, AUC=0.865) were significantly different between the groups. The duration of follow-up significantly differed between the groups (p<0.01), largely due to treatment of growing IA. During follow-up only one IA changing from stable to growing, and 5 of 6 subsequently treated IA were from within the initial growth group.

Conclusion: Several automated measures provided comparable performance to clinical size when assessing IA growth. HMAX in particular may be useful to assist clinical evaluation, as it was slightly more effective than recorded clinical size alone.

Abstract P531: Cerebral Blood Flow Analysis Using Flow Wire Measurements and CFD Analysis

Introduction: Clinical reports show that cerebral blood flow conditions are indicative of cerebral vascular disease. While methods for characterizing cerebral vascular flow have been extensively reported in the past, comparative analyses between direct flow measurements (DM) and computational flow dynamic (CFD) analysis remain limited. We hypothesize that flow data can be reliably measured both directly and through CFD in normal vessels.

Methods: A left heart replicator was used as a realistic cardiac pump which maintained systolic pressure at 120 mmHg and diastolic pressure at 80 mmHg. A stenotic model with 50% stenosis for the ICA was connected to the replicator. A ComboWire was used for DM and recorded flow pressure and velocity. CFD was used to study flow.

Results: In areas at the proximal end of the stenosis, the pressure and flow velocity derived from DM and CFD were in good agreement. At the end of systole and diastole, DM pressure were 145.42 mmHg and 73.53 mmHg, respectively. CFD simulation for the same system obtained the pressure at the end of systole and diastole of 147.16 mmHg and 74.64 mmHg, respectively. The velocity data collected from DM was at 15.40 cm/s and 7.74 cm/s for systolic flow and mean flow velocity. CFD measured flow was 17.85 cm/s and 11.37 cm/s, respectively. In areas at the distal end of the stenosis, pressure data showed good agreement between DM and CFD analysis. The DM were 138 and 70.81 mmHg at the end of systole and diastole, respectively; CFD simulation yielded 145.95 and 74.51 mmHg, respectively. Variations in the velocity data were observed at this location (Fig, pink arrows).

Conclusion: DM of pressure showed good agreement with CFD simulation in all areas of the vessel. DM of velocity using the flow wire were highly affected by location of the measurement. CFD analysis can provide more consistent flow data for flow information collection along the vasculature.

Impact of eloquent motor cortex-tissue reperfusion beyond the traditional thrombolysis in cerebral infarction (TICI) scoring after thrombectomy

Background

Targeted eloquence-based tissue reperfusion within the primary motor cortex may have a differential effect on disability as compared with traditional volume-based (thrombolysis in cerebral infarction, TICI) reperfusion after endovascular thrombectomy (EVT) in the setting of acute ischemic stroke (AIS).

Methods

We explored the impact of eloquent reperfusion (ER) within primary motor cortex (PMC) on clinical outcome (modified Rankin Scale, mRS) in AIS patients undergoing EVT. ER-PMC was defined as presence of flow on final digital subtraction angiography (DSA) within four main cortical branches, supplying the PMC (middle cerebral artery (MCA) – precentral, central, postcentral; anterior cerebral artery (ACA) – medial frontal branch arising from callosomarginal or pericallosal arteries) and graded as absent (0), partial (1), and complete (2). Prospectively collected data from two centers were analyzed. Multivariate analysis was conducted to assess the impact of ER-PMC on 90-day disability (mRS) among patients with anterior circulation occlusion who achieved partial reperfusion (TICI 2a and 2b).

Results

Among the 125 patients who met the study criteria, ER-PMC distribution was: absent (0) in 19/125 (15.2%); partial (1) in 52/125 (41.6%), and complete (2) in 54/125 (43.2%). TICI 2b was achieved in 102/125 (81.6%) and ER-PMC was substantially higher in those patients (P<0.001). In multivariate analysis, in addition to age and symptomatic intracranial hemorrhage, ER-PMC had a profound independent impact on 90-day disability (OR 6.10, P=0.001 for ER-PMC 1 vs 0 and OR 9.87, P<0.001 for ER-PMC 2 vs 0), while the extent of total partial reperfusion (TICI 2b vs 2a) was not related to 90-day mRS.

Conclusions

Eloquent PMC-tissue reperfusion is a key determinant of functional outcome, with a greater impact than volume-based (TICI) degree of partial reperfusion alone. PMC-targeted revascularization among patients with partial reperfusion may further diminish post-stroke disability after EVT.

Increased Rate of Successful First Passage Recanalization During Mechanical Thrombectomy for M2 Occlusion

BACKGROUND

Mechanical thrombectomy (MT) is the standard of care for the treatment of acute ischemic stroke (AIS) caused by anterior circulation large-vessel occlusion. However, the true safety and efficacy of MT in medium-size vessel occlusions such as the M2 segment of the middle cerebral artery have yet to be completely defined. In this study, we analyze the safety and efficacy of MT in M2 occlusions compared with M1 occlusions.

METHODS

A retrospective analysis was performed of patients with AIS secondary to M1 and M2 occlusions between 2011 and 2018. The inclusion criteria were 1) AIS secondary to M1 or M2 occlusion, 2) MT performed by stentrieval technique alone, aspiration technique, or combined stentrieval-aspiration techniques. Basic patient characteristics, number of passages, first passage recanalization success (≥TICI [Thrombolysis in Cerebral Ischemia] grade 2b), total recanalization success, hemorrhagic complications (including intracerebral hemorrhage [ICH] and subarachnoid hemorrhage), and clinical outcomes were compared between both groups.

RESULTS

Two hundred and sixty patients met the inclusion criteria; 171 patients had M1 occlusion versus 89 with M2 occlusion. First passage recanalization success rate was significantly higher in the M2 group (55.1% vs. 39.2%; P = 0.015). Total recanalization success rate was higher in the M2 group but did not reach significance (83% vs. 75%; P = 0.128). Subarachnoid hemorrhage rate was significantly higher in the M2 group (25% vs. 12%; P = 0.010) but there was no difference for ICH complications (14.6% vs. 16.4%; P = 0.711).

CONCLUSIONS

MT for M2 occlusions has similar overall efficacy to that for M1 occlusions, but with higher first-pass successful recanalization rates. MT for M2 occlusions has a higher risk of associated subarachnoid hemorrhage.

Abstract WMP27: PAT Model Accurately Predicts Aneurysm Enlargement in 16 Growing Aneurysm Cases

Objective: Imaging technology for unruptured intracranial aneurysms (UIA) has improved detection of such aneurysms. However, there is limited information on UIA change over time, and how to predict the rate of enlargement. The objective of this study was to quantify the accuracy of the Predicted Aneurysm Trajectory (PAT) model recently developed by Chien et al. (J Neurosurgery. 2019; Mar 1:1-11).

Methods: Patients diagnosed with UIA were prospectively enrolled at the UCLA Medical Center, and followed through serial imaging. 16 UIA cases exhibiting growth across multiple follow-ups were included in this study. Prior images and medical records were collected. Characteristics relevant to the PAT model (mean ± stdev), including initial UIA size (7.26 ± 6.38), patient age (67.4 ± 9.48 yrs.), sex (4 male), history of smoking (n=5), hypothyroidism (n=4), and follow-up duration (36.5 ± 50.0 mos.) were used to predict UIA size at each follow-up. Predicted and actual UIA sizes at follow-up were compared using symmetric mean absolute percentage error (SMAPE) with percentage error ranging from 0-100%.

Results: The 16 UIA cases were split by initial UIA size. For UIA smaller than 7 mm (10 cases, 23 follow-up), SMAPE = 11.13%. For UIA greater than 7 mm (6 cases, 15 follow-up), SMAPE = 8.07%. For all UIA cases (16 cases, 38 follow-up), SMAPE = 9.92%.

Conclusions: The PAT model predicts the rate of enlargement for UIA, as opposed to whether or not UIA will grow. With this new sample of data, we found the predicted UIA size at follow-up to be quite accurate, deviating in the range of 10% from the actual, measured size. Patient characteristics such as the demographics and behavior included in the model influence the growth of UIA, which allows prediction of growth to optimize treatment and management in future cases.

Unruptured intracranial aneurysm growth trajectory: occurrence and rate of enlargement in 520 longitudinally followed cases

OBJECTIVE

As imaging technology has improved, more unruptured intracranial aneurysms (UIAs) are detected incidentally. However, there is limited information regarding how UIAs change over time to provide stratified, patient-specific UIA follow-up management. The authors sought to enrich understanding of the natural history of UIAs and identify basic UIA growth trajectories, that is, the speed at which various UIAs increase in size.

METHODS

From January 2005 to December 2015, 382 patients diagnosed with UIAs (n = 520) were followed up at UCLA Medical Center through serial imaging. UIA characteristics and patient-specific variables were studied to identify risk factors associated with aneurysm growth and create a predicted aneurysm trajectory (PAT) model to differentiate aneurysm growth behavior.

RESULTS

The PAT model indicated that smoking and hypothyroidism had a large effect on the growth rate of large UIAs (≥ 7 mm), while UIAs < 7 mm were less influenced by smoking and hypothyroidism. Analysis of risk factors related to growth showed that initial size and multiplicity were significant factors related to aneurysm growth and were consistent across different definitions of growth. A 1.09-fold increase in risk of growth was found for every 1-mm increase in initial size (95% CI 1.04-1.15; p = 0.001). Aneurysms in patients with multiple aneurysms were 2.43-fold more likely to grow than those in patients with single aneurysms (95% CI 1.36-4.35; p = 0.003). The growth rate (speed) for large UIAs (≥ 7 mm; 0.085 mm/month) was significantly faster than that for UIAs < 3 mm (0.030 mm/month) and for males than for females (0.089 and 0.045 mm/month, respectively; p = 0.048).

CONCLUSIONS

Analyzing longitudinal UIA data as continuous data points can be useful to study the risk of growth and predict the aneurysm growth trajectory. Individual patient characteristics (demographics, behavior, medical history) may have a significant effect on the speed of UIA growth, and predictive models such as PAT may help optimize follow-up frequency for UIA management.

Abstract WP126: A Predictive Model for Intracranial Aneurysm Growth Trajectory

Introduction: The rate of growth of a particular intracranial aneurysm (IA) is relevant for assessing the risk posed by the IA, and determining an appropriate management strategy. However, the rate of growth cannot currently be estimated when an IA is detected. By determining the association of various factors with IA growth rate based on longitudinally followed aneurysm data, we have developed a predictive model for the patient-specific IA growth trajectory.

Hypothesis: If a particular IA will grow, its course of growth is largely determined by the characteristics of the patient and the IA itself.

Methods: This study utilized a retrospective dataset of 382 patients with 520 IA diagnosed between 2005-2015. Medical images and electronic medical records were used to build the predictive model. IA were monitored for 32.7 ± 25.4 months, with a mean of three CTA image studies monitoring IA growth or lack thereof, comprising 1,636 data points. Multivariate adaptive splines for analysis of longitudinal data (MASAL) was utilized to guide the development of multivariate linear mixed models for two-level data.

Results: MASAL showed that initial size was significantly associated with stroke, hypertension, coronary artery disease, atrial fibrillation, and diabetes mellitus. Therefore, these patient-specific factors were eliminated to avoid overfitting. Smoking history (previous or current) and diagnosis of thyroid disease were found to be independent variables for growth rate prediction and were used to build the model. Our preliminary model found different growth patterns for IA with different initial sizes. We also found that the growth rate of large IA (>7 mm) was more strongly influenced by smoking and thyroid disease. Growth of IA in patients with thyroid disease was found to slow down significantly after 24 months of follow-up, suggesting IA do not grow linearly.

Conclusions: We present the first attempt to model IA growth based on medical data and 3D image data for aneurysm cases collected longitudinally over the past 10 years. Our results show it may be possible to predict rate of growth on an individual and aneurysm-specific basis.

Abstract WP121: Patient- and Aneurysm-specific Predictors of Intracranial Aneurysm Growth in a Longitudinally-followed Population

Introduction: Intracranial aneurysms (IA) which occur in adults are assumed to undergo growth at some point during their natural history. However, the factors which may contribute to IA growth in certain individuals are largely unresolved, with significant variation between previous studies. In this study we examine 520 IA which were longitudinally followed by 3D CT images. We examined 21 patient- and aneurysm-specific factors (including patient medical history, aneurysm size, location and multiply) with potential relevance to IA growth.

Hypothesis: Patient- and aneurysm-specific characteristics may determine whether an IA is likely to grow.

Methods: IA were diagnosed between 2005-2015 and were longitudinally followed with medical imaging (CTA). Univariate logistic regression with calculation of odds ratios (OR) and 95% confidence intervals (95% CI) were determined using univariate logistic regression with a growth threshold defined as an IA size increase greater than 0.6 mm.

Results: Every 1 mm increase in initial IA size was associated with a significant 1.09-fold increase in risk of growth (95% CI: 1.04-1.15; P=0.001). Compared to patients with single IA, in patients with multiple IA, IA were 2.43-fold more likely to grow (95% CI: 1.36-4.35; P=0.003). A diagnosis of hypertension was found to associate with a borderline significant 1.76-fold increased risk of IA growth compared to patients who did not have hypertension (95% CI: 0.93-3.32; P=0.082).

Conclusions: Previous meta-analyses have found predictors of IA growth to be extremely heterogeneous, exacerbated by the relatively small sample size of many of the included studies. In this context, our finding of IA size to be a significant predictor of growth and hypertension to be borderline significant in a relatively large set of cases contributes valuable additional data to understanding IA growth.

Abstract TP87: Hemodynamic Differences Observed between Growing and Stable Symmetric MCA Bifurcation Aneurysms

Introduction: The analysis of symmetric aneurysms can control for genetic differences in studies of aneurysm growth. This study aims to evaluate the differences in hemodynamic flow between growing and stable aneurysms symmetrically located at the middle cerebral artery (MCA) bifurcation.

Hypothesis: Differences in the hemodynamic flow exist between growing and stable symmetric aneurysms at the MCA bifurcation.

Methods: 6 patients with symmetric pairs of MCA bifurcation aneurysms were followed with CTA imaging for a mean of 19.82 ± 7.68 months, across 2.67 ± 0.52 imaging scans. In three patients both aneurysms were stable, while in three others one of the aneurysms exhibited growth. 16 computational flow simulations of the complete Circle of Willis, each including a pair of symmetric aneurysms, were run based on the CTA imaging studies. Blood flow at the neck, body, and dome of each aneurysm was analyzed. Welch’s t-test was used to compare growing and stable groups.

Results: The mean diameters were 4.46±2.29 mm for the growing aneurysms and 4.24±1.99 mm for the stable aneurysms (p=0.8). No significant difference in wall shear stress (WSS) was found between growing and stable aneurysms (p=0.14). However, the growing aneurysms exhibited a significantly higher neck pulsatility index (PI) (1.33±0.27 vs 1.02±0.52, p=0.05) and a lower body PI (1.04±0.41 vs 1.69±0.76, p<0.01). Stable aneurysms in patients with a growing symmetric aneurysm had significantly lower dome PI (1.61±0.32 vs. 2.56±1.26, p=0.01) and overall higher WSS (p=0.02) (5.49±4.42 vs. 3.16±3.54) than bilaterally stable aneurysms.

Conclusion: Stable aneurysms with symmetric growing aneurysms share similar hemodynamic characteristics and may be at risk for future growth. In general, interpatient aneurysm hemodynamic differences were more significant than intrapatient differences. Such patient-specific differences may arise from the tortuosity of the cerebral vascular tree.

Increased affinity of endothelial cells to NiTi using ultraviolet irradiation: An in vitro study

Nickel-titanium alloy (NiTi) is one of the most popular materials used endovascularly because of its shape memory and superelasticity. The NiTi device needs to be covered by endothelial cells after being placed in the blood vessel to reduce ischemic complications. The objective of this study was to examine the impact of ultraviolet (UV) irradiation on the biocompatibility of NiTi surfaces with endothelial cells. NiTi sheets were treated with UV irradiation for 48 h and human aorta derived endothelial cells were used in this study. UV irradiation converted the NiTi surface to hydrophilic state and increased albumin adsorption. The number of endothelial cell migration, attachment, proliferation as well as their metabolic activity were significantly increased on UV treated NiTi. This study provides the first evidence of the photoactivation of NiTi surfaces by UV irradiation and demonstrates improved biocompatibility of UV-treated NiTi surfaces with vascular endothelial cells. These results suggest that UV irradiation may promote endothelialization of NiTi devices in blood vessels. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 1034-1038, 2018.

Feasibility and utility of an integrated medical imaging and informatics smartphone system for management of acute stroke

Background

Rapid dissemination and coordination of clinical and imaging data among multidisciplinary team members are essential for optimal acute stroke care.

Aim

To characterize the feasibility and utility of the Synapse Emergency Room mobile (Synapse ERm) informatics system.

Methods

We implemented the Synapse ERm system for integration of clinical data, computerized tomography, magnetic resonance, and catheter angiographic imaging, and real-time stroke team communications, in consecutive acute neurovascular patients at a Comprehensive Stroke Center.

Results

From May 2014 to October 2014, the Synapse ERm application was used by 33 stroke team members in 84 Code Stroke alerts. Patient age was 69.6 (±17.1), with 41.5% female. Final diagnosis was: ischemic stroke 64.6%, transient ischemic attack 7.3%, intracerebral hemorrhage 6.1%, and cerebrovascular-mimic 22.0%. Each patient Synapse ERm record was viewed by a median of 10 (interquartile range 6–18) times by a median of 3 (interquartile range 2–4) team members. The most used feature was computerized tomography, magnetic resonance, and catheter angiography image display. In-app tweet team, communications were sent by median 1 (interquartile range 0–1, range 0–13) users per case and viewed by median 1 (interquartile range 0–3, range 0–44) team members. Use of the system was associated with rapid treatment times, faster than national guidelines, including median door-to-needle 51.0 min (interquartile range 40.5–69.5) and median door-to-groin 94.5 min (interquartile range 85.5–121.3). In user surveys, the mobile information platform was judged easy to employ in 91% (95% confidence interval 65%–99%) of uses and of added help in stroke management in 50% (95% confidence interval 22%–78%).

Conclusion

The Synapse ERm mobile platform for stroke team distribution and integration of clinical and imaging data was feasible to implement, showed high ease of use, and moderate perceived added utility in therapeutic management.

Coil embolization through the Marathon microcatheter: Advantages and pitfalls

Due to technical limitations, small, distal, and tortuous intracranial pathology is sometimes out of reach of the current armamentarium of microcatheters designed for intracranial coil embolization. The Marathon microcatheter (Medtronic, Minneapolis, Minnesota, USA), designed specifically for the delivery of Onyx, is longer and more flexible than most coil delivery catheters. We report on nine patients (three with arteriovenous fistula, three with arteriovenous malformation, two with intracranial aneurysm, and one with tumor) where Marathon was used to deliver commercially available platinum coils. We also conducted laboratory compatibility testing and conclude that the Marathon can be used as a coil delivery catheter for Barricade coils (Blockade Medical, Irvine, California, USA) with diameter less than 0.012 in.

Abstract WMP68: Smartphone Support System for Mobile Imaging Display and Management of Acute Stroke

Introduction: Rapid dissemination and coordination of clinical and imaging data among multidisciplinary team members is essential for optimal acute stroke care. Standard desktop EMRs are ill-suited for this purpose, but mobile smartphone and tablet applications are highly promising platforms for accelerated, data-driven patient diagnosis and treatment. This study tested an advanced mobile integrated system for distribution of patient clinical and imaging information.

Methods: We tested the iStroke/Synapse ERm system (Figure) for smartphone and tablet display and integration of clinical data, CT, MR, and catheter angiographic imaging, and real-time stroke team communications, in consecutive acute neurovascular patients at a Comprehensive Stroke Center.

Results: From 5/2014 to 10/2014, the Synapse ERm application was installed and used by 33 stroke team members, in 84 Code Stroke ED patients. Patient age was 69.1 (±17.5), with 40.5% female. Final diagnosis was: ischemic stroke 66%, TIA 7%, ICH 6%, and CV mimic 21%. Each patient record was viewed on average 13 times by at least 3 team members. The most used feature was CT, MR and cath angio image display, viewed on average 4 times per patient by at least 2 users. In-app tweet team communications were sent by average 2 users per case and viewed by average 6 team members. Use of the system was associated with treatment times that exceeded national guideline targets for thrombolysis and endovascular thrombectomy, including door-to-needle 50 min (IQR 24-60) and door-to-groin 92 min (IQR 65-128). In user surveys, the mobile information platform was judged easy to employ in 91% of uses and of added help in stroke management in a substantial majority of cases.

Conclusion: The Synapse ERm system, a smartphone/tablet platform for stroke team communication and distribution and integration of clinical and imaging data, showed high ease of use, substantial added management value, and association with rapid processes of care.

Abstract WMP30: Quantitative Aneurysm Flow Evaluation of Combined FD and Coil Treatment Shows Higher Flow Reduction During the Healing Process Based on 2D DSA Images

Purpose: This pilot study demonstrates an approach to quantitatively evaluate the effectiveness of flow diverter (FD) stents and coil treatments based on follow-up images.

Method: 2D digital subtraction angiography (DSA) images from 18 aneurysm patients were analyzed using IS FlowMap flow analysis software. Each patient had DSA images (3 frames/sec) acquired before, after the FD treatment and during follow-up examinations. 11 patients received FD treatment, and 7 patients received FD and coil combined treatment. The percentage of blood flow redirected into the parent artery was calculated. The relative aneurysm blood flow reduction caused by the stent was obtained. Based on the inlet contrast (CA) concentration profile, the blood flow changes in aneurysm and vessel blood flow were obtained.

Result: 18 patients’ average aneurysm blood flow reduction was 52% after the treatment. All scaled aneurysm CA concentration profile slopes before and after the treatment showed a clear difference (p=0.003). Post-treatment aneurysm CA slopes decreased 36% in average compared to pre-treatment, indicating a lower inflow rate of blood entering the aneurysm after the treatment. 7 patients with FD and coil combined treatment showed an average of 54% aneurysm blood flow reduction right after the treatment. FD and coil combined treatment had an average of 73% aneurysm blood flow reduction in patients’ first DSA follow up (8±3 months post treatment). Representative cases of FD and Coil combined treatment (flow reduction 53% right after the treatment; 89% at the 8 month follow-up) and FD only (flow reduction 48% right after the treatment; 75% at the 6 month follow-up) are shown in the figure.

Conclusion: IS FlowMap quantitatively measures the effectiveness of treatment in patients with brain aneurysms using only 2D DSA. The result suggests that FD and coil combined treatment is more effective in preventing aneurysm blood inflow during the healing process.

Predictors of thrombotic complications and mass effect exacerbation after pipeline embolization: The significance of adenosine diphosphate inhibition, fluoroscopy time, and aneurysm size

BACKGROUND

The mechanisms leading to delayed rupture, distal emboli and intraparenchymal hemorrhage in relation to pipeline embolization device (PED) placement remain debatable and poorly understood. The aim of this study was to identify clinical and procedural predictors of these perioperative complications.

METHODS

We conducted a retrospective review of consecutive patients who underwent PED placement. We utilized a non-commercial platelet aggregation method measuring adenosine diphosphate (ADP)% inhibition for evaluation of clopidogrel response. To our knowledge, this is the first study to test ADP in neurovascular procedures. Multivariable regression analysis was used to identify the strongest predictor of three separate outcomes: (1) thrombotic complications, (2) hemorrhagic complications, and (3) aneurysm mass effect exacerbation

RESULTS

Permanent complication-related morbidity and mortality at 3 months was 6% (3/48). No specific predictors of hemorrhagic complications were identified. In the univariate analysis, the strongest predictors of thrombotic complications were: ADP% inhibition<49 (p=0.01), aneurysm size (p=0.04) and fluoroscopy time (p=0.002). In the final multivariate analysis, among all baseline variables, fluoroscopy time exceeding 52 min was the only factor associated with thrombotic complications (p=0.007). Aneurysm size≥18 mm was the single predictor of mass effect exacerbation (p=0.039).

CONCLUSIONS

Procedural complexity, reflected by fluoroscopy time, is the strongest predictor of thrombotic complications in this study. ADP% inhibition is a reliable method of testing clopidogrel response in neurovascular procedures and values of <50% may predict thrombotic complications. Interval mass effect exacerbation after PED placement may be anticipated in large aneurysms exceeding 18 mm.

Collateral flow as causative of good outcomes in endovascular stroke therapy

BACKGROUND

Endovascular reperfusion techniques are a promising intervention for acute ischemic stroke (AIS). Prior studies have identified markers of initial injury (arrival NIH stroke scale (NIHSS) or infarct volume) as predictive of outcome after these procedures. We sought to define the role of collateral flow at the time of presentation in determining the extent of initial ischemic injury and its influence on final outcome.

METHODS

Demographic, clinical, laboratory, and radiographic data were prospectively collected on a consecutive cohort of patients who received endovascular therapy for acute cerebral ischemia at a single tertiary referral center from September 2004 to August 2010.

RESULTS

Higher collateral grade as assessed by the American Society of Interventional and Therapeutic Neuroradiology/Society of Interventional Radiology (ASITN/SIR) grading scheme on angiography at the time of presentation was associated with improved reperfusion rates after endovascular intervention, decreased post-procedural hemorrhage, smaller infarcts on presentation and discharge, as well as improved neurological function on arrival to the hospital, discharge, and 90 days later. Patients matched by vessel occlusion, age, and time of onset demonstrated smaller strokes on presentation and better functional and radiographic outcome if found to have superior collateral flow. In multivariate analysis, lower collateral grade independently predicted higher NIHSS on arrival.

CONCLUSIONS

Improved collateral flow in patients with AIS undergoing endovascular therapy was associated with improved radiographic and clinical outcomes. Independent of age, vessel occlusion and time, in patients with comparable ischemic burdens, changes in collateral grade alone led to significant differences in initial stroke severity as well as ultimate clinical outcome.

Immunohistochemical analysis of a ruptured basilar top aneurysm autopsied 22 years after embolization with Guglielmi detachable coils

The authors report on the histologic and immunohistochemical analyses of a cerebral aneurysm embolized with platinum coils and with the longest observation period. A 58-year-old woman presenting with subarachnoid hemorrhage due to ruptured basilar top aneurysm was treated with Guglielmi detachable coils (GDC) 22 years ago. She was the 15th case since the GDC was introduced. After she died of unrelated causes, an autopsy and thorough histologic examination were performed. Gross examination revealed no adhesion between the aneurysm wall and the surrounding brain tissue. Histologic and immunohistochemical analyses demonstrated that the cavity of the aneurysm was filled with homogeneous collagenous fibrous tissue, while the neck was completely covered by a dense collagenous neointima and a smooth muscle cell layer. The unique histologic results of this case may contribute to a better understanding of the long-term evolution of the healing process in intracranial aneurysms successfully treated with the GDC.

Aneurysm pressure measurement before and after placement of a Pipeline stent: feasibility study using a 0.014 inch pressure wire for coronary intervention

Flow-diverting stents have provided a new endovascular capacity to reconstruct an intracranial aneurysm with its diseased parent artery. The results of first-generation flow diversion stents have been encouraging, with even large or giant treated aneurysms achieving complete angiographic occlusion at 12-month follow-up. Numerous clinical reports have described a slow progressive thrombosis pattern and gradual increase in rate of complete aneurysm obliteration over time. Despite promising early results, some complications specific to flow-diverting stents have been encountered. Chief among them is delayed aneurysm rupture. This complication did not emerge with stent-assisted coil embolization of intracranial aneurysms, and the underlying cause has not been established. However, new evidence suggests that persistent, or even increased, aneurysm pressure after stent placement may play a role in some delayed ruptures. We sought to evaluate this phenomenon by measuring intrasaccular pressure before and after stent placement using two different 0.014 inch coronary pressure measurement wires. Two patients with giant internal carotid artery aneurysms treated with flow-diverting stents were evaluated. Before and after stent deployment, intrasaccular aneurysm and systemic arterial pressures were recorded for 60 s and compared. In both cases, intrasaccular pressure measurement with the use of 0.014 inch pressure wire system was feasible; the pressure wires could be pushed out of the microcatheter placed in the aneurysms without friction or unexpected microcatheter motion. Despite successful flow-diverting stent deployment and angiographic flow diversion effects with excellent wall opposition across the aneurysm necks, there was no significant difference between intrasaccular and systemic pressures.

M2 occlusions as targets for endovascular therapy: comprehensive analysis of diffusion/perfusion MRI, angiography, and clinical outcomes

BACKGROUND

The ideal population of patients for endovascular therapy (ET) in acute ischemic stroke remains undefined. Recent ET trials have moved towards selecting patients with proximal middle cerebral artery (MCA) or internal carotid artery occlusions, which will likely leave a gap in our understanding of the treatment outcomes of M2 occlusions.

OBJECTIVE AND METHODS

To examine the presentation, treatment, and outcomes of M2 compared with M1 MCA occlusions in patients undergoing ET by assessing comprehensive MRI, angiography, and clinical data.

RESULTS

We found that M2 occlusions can lead to massive strokes defined by hypoperfused and infarcted volumes as well as death or moderate to severe disability in nearly 50% of patients at discharge. Compared with M1 occlusions, M2 occlusions achieved similar Thrombolysis in Cerebral Infarction (TICI) 2b/3 recanalization rates, with significantly less hemorrhage. M2 occlusions presented with smaller infarct and hypoperfused volumes and had smaller final infarct volumes regardless of recanalization. TICI 2b/3 recanalization of M2 occlusions was associated with smaller infarct volumes compared with TICI 0-2a recanalization, as well as less infarct expansion, in patients who received IV tissue plasminogen activator as well as those that did not. Successful reperfusion of M2 occlusions was associated with improved discharge modified Rankin scale.

CONCLUSIONS

If suitable as targets of ET, M2 occlusions should be given the same consideration as M1 occlusions.

Abstract W MP31: Thrombotic and Hemorrhagic Complications After Pipeline Embolization - A Platelet Aggregation and Transcranial Doppler Study

In this study, we sought to determine the correlation between the pre-treatment platelet aggregation, and the respective occurrence of thrombotic and hemorrhagic complications after pipeline embolization device (PED) for treatment of intracranial aneurysms. In addition, we evaluated the cerebral hemodynamics and the presence of silent emboli after PED placement in some patients utilizing transcranial Doppler (TCD).

Methods: We analyzed the clinical and imaging characteristics of 46 consecutive patients who underwent 48 PED procedures. All patients received double antiplatelet therapy with Clopidogrel 75mg and Aspirin 325mg daily for at least 3 days prior to the planned procedure. Platelet aggregation testing was performed in 41/48 (86%) procedures. Based on the initial ADP % inhibition, patients were divided in 3 groups in the present study: 1) poor responders: <50%, 2) satisfactory responders: 50-75%, and 3) over-responders: > 75%

Results: Hemorrhagic complications requiring escalation of care occurred in 15% (7/48) of all procedures, including 3 patients with symptomatic ICH. 2/3 ICHs occurred in a remote vascular territory in reference to the treated aneurysm, one of which was fatal. Thrombotic complications occurred at a rate of 13% (6/48), of which 3 (9%) were symptomatic. Permanent complication-related morbidity and mortality at 6 months was 4% (2/48).

Of all patients with available platelet aggregation testing (n=41), 13 (31%) were poor Clopidogrel responders. Of those, 6 were switched to an alternative antiplatelet regimen. Thrombotic complications occurred mostly in the poor responders group who had no change in their regimen (27% vs. 4%; p=0.05).

Intracranial hemorrhage occurred entirely in the over-responders group, (0% vs. 14%; p=0.08). None of the TCD demonstrated presence of silent emboli. In addition, 10/11 patients had elevated flow velocities after the PED placement.

Conclusions:

1. Pre-treatment Clopidogrel response, measured by ADP % inhibition may predict thrombotic and/or hemorrhagic complications after PED placement.

2. Distal embolization likely occurs mostly during, but not after the procedure as suggested by the TCD data in this study.

Abstract W P73: Feasibility and Preliminary Results of Whole Blood RNA-Sequencing Analysis in Patients With Intracranial Aneurysms

Introduction: Intracranial aneurysms (IA) growth and rupture have been associated with chronic remodeling of the arterial wall. However, the pathobiology of this process remains poorly understood. The objective of the present study was to evaluate the feasibility of analyzing gene expression patterns in peripheral blood of patients with ruptured and unruptured saccular IAs.

Materials and Methods: We analyzed human whole blood transcriptomes by performing paired-end, 100 bp RNA-sequencing (RNAseq) using the Illumina platform. We used STAR to align reads to the genome, HTSeq to count reads, and DESeq to normalize counts across samples. Self-reported patient information was used to correct expression values for ancestry, age, and sex. We utilized weighted gene co-expression network analysis (WGCNA) to identify gene expression network modules associated with IA size and rupture. The DAVID tool was employed to search for Gene Ontology enrichment in relevant modules.

Results: Samples from 12 patients (9 females, age 57.6 +/-12) with IAs were analyzed. Four had ruptured aneurysms. RNA isolation and application of the methodology described above was successful in all samples. Although the small sample size prevents us from drawing definite conclusions, we observed promising novel co-expression networks for IAs: WCGNA analysis showed down-regulation of two transcript modules associated with ruptured IA status (r=-0.78, p=0.008 and r=-0.77, p=0.009), and up-regulation of two modules associated with aneurysm size (r=0.86, p=0.002 and r=0.9, p=4e-04), respectively. DAVID analyses showed that genes upregulated in an IA size-associated module were enriched with genes involved in cellular respiration and translation, while genes involved in transcription were down-regulated in a module associated with ruptured IAs.

Conclusions: Whole blood RNAseq analysis is a feasible tool to capture transcriptome dynamics and achieve a better understanding of the pathophysiology of IAs. Further longitudinal studies of patients with IAs using network analysis are justified.

Abstract T MP30: Cerebral Arteriogenesis and Angiogenesis: Distinct Angioarchitecture of Innate and EDAS Collaterals in Intracranial Arterial Steno-Occlusive Disease

Introduction: Patients with ICASD form various degrees of collateralization. However, those collaterals fail over time contributing to symptom progression. Indirect revascularization via encephaloduroarteriosynangiosis (EDAS) establishes collateral flow through new vessels formed from external carotid branches in both moyamoya disease (MMD) and non-moyamoya (NM) ICASD. We hypothesize that the EDAS neovascularization differs in terms of angioarchitecture when compared to spontaneously formed collaterals in ICASD.

Methods: We analyze pre and post-operative digital subtraction angiograms (DSA) of patients enrolled in a prospective trial of EDAS surgery using ImageJ software (http://imagej.nih.gov/ij). Angioarchitectural differences between innate and post-EDAS collaterals were evaluated by comparing their branching angioscore (BA) and artery tortuosity index (ATI).

Results: Images from 26 patients, ages 4 to 84 (mean: 37 SD+/-19.5) were evaluated. Patients included 13 MMD and 13 NM-ICASD. Postoperative mean DSA time was 14 months. Post-EDAS collaterals had significantly higher BA and lower ATI than innate collaterals (BA: 9.8 vs. 5.5 and ATI 110 vs. 167 [p<0.001] respectively). Subgroup analyses for patients with MMD and NM-MMD demonstrated the same pattern with higher BA for post-EDAS collaterals and lower ATI for innate collaterals (MMD: BA: 9.6 vs. 5.2, and ATI 107.7 vs.176.5, NM-ICASD: BA: 9.9 vs. 5.8, and ATI: 153.7 vs.115.4 p≤0.01). Type of ICASD, age, or time after angiography did not affect the indexes.

Conclusions: Collaterals formed after EDAS differ in angioarchitecture to innate collaterals in MMD and NM-ICASD. Morphological differences are consistent with two distinct mechanisms of vessel formation: innate collaterals formed by arteriogenesis display high tortuosity and low branching as expected by a shear stress process acting on pre-existing conduits. Conversely, post-EDAS collaterals have higher branching and lower tortuosity as expected in a process of angiogenesis in which collaterals form through sprouting and splitting from the donor vessels.

Abstract W P47: Recanalization After IV TPA Alone Among Acute Ischemic Stroke Patients Treated With Combined IV-Endovascular Recanalization: Impact of Arterial Occlusion Site

Background: Combined IV TPA and catheter-based reperfusion is an emerging treatment strategy for acute ischemic stroke. Both patient care and clinical trial design would be enhanced by delineation of which patients rapidly respond to IV TPA alone, before endovascular therapy can be initiated.

Methods: In a prospectively maintained registry of patients treated under a general policy of combined IV TPA and endovascular therapy, we analyzed subjects with MRA/CTA-confirmed anterior circulation occlusions prior to IV TPA start.

Results: Among 118 patients meeting study entry criteria, age was mean 71.5 (SD 14.5), 53.0% were female, and baseline NIHSS was 14.4 (SD 7.1). Confirmed sites of occlusion prior to IV TPA were internal cerebral artery (ICA) in 22.9%, M1 segment of middle cerebral artery (MCA) in 50.0%, and M2-3 in 27.1%. Among patients undergoing catheter cerebral angiography, median time from start of IV TPA to diagnostic catheter angiogram was 75 mins (IQR 50-113). A total of 48 (40.7%) patients achieved partial or complete recanalization (AOL 2-3) of the initial target artery with IV TPA alone (partial in 22 (18.6%) and complete in 26 (22.2%)); an additional 44 (37.3%) achieved partial or complete recanalization after endovascular therapy. Recanalization rates after IV TPA alone varied by target occlusion site: ICA - 22.2%, M1 - 40.7%, and M2-3 - 56.2%. In multivariate logistic regression analysis, independent predictors of recanalization with IV TPA alone were: M2-3 clot location, OR 3.04 (95% CI 1.20-7.73, p=0.019) and TOAST etiology large-artery atherosclerosis, OR 0.14 (CI 0.04-0.50, p = 0.003). Good outcome (mRS ≤ 3) rates at 3 months were 76.6% among recanalizers with IV TPA alone and 47.5% among recanalizers after both IV TPA and catheter therapy.

Conclusions: When combined IV-endovascular treatment is pursued, recanalization with IV TPA alone occurs in 4 out of 10 patients before catheter therapy is started, is more common with more distal clot location, and is associated with a high rate of excellent clinical outcomes.

Abstract W P70: What Cfd Parameter is Different Between Growing and No Growing Aneurysm

Background & Purpose: Research has not yet identified the growth mechanism of cerebral aneurysms. We investigated the values of CFD-derived parameters in cases of growing and non- growing aneurysms.

Methods: We extracted 30 growing and 30 non- growing aneurysm cases randomly from our database. Commercially available software (ANSYS ICEM CFD14.0) was used for both mesh generation and fluid simulation. The aneurysm geometries were extracted from CTA and analyzed using a mathematical formula for fluid flow under pulsatile blood flow conditions. Simulations were performed before and after growth, and hemodynamic parameters were compared between the two growing and no-growing groups.

Result: In the growing aneurysms group, The the “growth” area is was different from the bloodstream inflow “impact” area. There was no statistically significant difference in velocity, WSS and OSI between growing and no growing cases. Pressure, however, was significantly different between the two groups(P<0.05).

Conclusion: CFD-derived pressure values in the aneurysm dome may predict growth of aneurysms and therefore may also predict rupture.

Abstract T P33: Collateral Grade on MRI - Validation With Conventional Angiography is Key

Introduction: Collateral status may predict outcomes after endovascular therapy, yet a reliable noninvasive technique prior to angiography is needed. We developed a novel method for projection of perfusion imaging data and validated it with respect to DSA acquired immediately afterwards.

Methods: Consecutive acute ischemic stroke patients with M1 MCA occlusions with perfusion MR imaging prior to endovascular revascularization therapy were included. Collateral status on DSA was graded with the ASITN/SIR scale (0-4). 4-D dynamic susceptibility contrast concentration time images were constructed and projected in 2-D axial and sagittal planes at each time point. Independent review of the resulting MRI-based collateral sequences was conducted to generate a score analogous to the ASITN/SIR scale, followed by correlation studies between the two techniques.

Results: 47 patients were included with mean age 68.5 ± 16.3, 76.5% were female, baseline NIHSS was median 14 (range 3-31), and mean time from MRI to groin puncture was 109 min ± 95.5. DSA collateral grade was (0 (n=3); 1 (n=9); 2 (n=12); 3 (n=21); 4 (n=2)) with MRI collateral grade (0 (n=2); 1 (n=11); 2 (n=13); 3 (n=18); 4 (n=2)). MRI and DSA collateral scores were closely correlated, Spearman's rho = 0.91, weighted kappa = 0.82 (P <0.00001). Poor collateral status on MRI showed correlations with moderate to severe NIHSS (Spearman's rho = -0.31 (p< 0.039)). Figure depicts a panel version of MRI-based collateral sequences from a patient with a left M1 occlusion with a MR collateral grade of 1.

Conclusions: Novel post-processing of noninvasive MRI perfusion data based on routine acquisitions can reliably measure the degree of collaterals on DSA.

Development of medical devices for neurointerventional procedures: special focus on aneurysm treatment

Since the introduction of the Guglielmi detachable coil in 1990, the role of endovascular treatment for intracranial aneurysm has changed significantly. However, this endovascular modality has intrinsic technical limitations in wide-neck and large (11-25 mm) or giant (>25 mm) aneurysms. Long-term anatomic outcomes for these aneurysms include an approximate 25% recanalization rate. Since the aneurysm recanalization is related to morphologic, hemodynamic and biologic factors associated with aneurysm healing, improvement of these factors has elicited several technical modifications of the original technique. This review will describe new endovascular devices that have been manufactured to improve the technical limitations inherited by the Guglielmi detachable coil technique, as well as the historic background of endovascular treatment for cerebral aneurysms.

Angioarchitectural characteristics associated with initial hemorrhagic presentation in supratentorial brain arteriovenous malformations

OBJECTIVE

The difference in arterial supply, venous drainage, functional localization in supratentorial and infratentorial compartments may contribute to the conflicting results about risk factors for hemorrhage in published case series of brain arteriovenous malformation (bAVM). Further investigation focused on an individual brain compartment is thus necessary. This retrospective study aims to identify angioarchitectural characteristics associated with the initial hemorrhagic event of supratentorial bAVMs.

MATERIALS AND METHODS

The clinical and angiographic features of 152 consecutive patients with supratentorial bAVMs who presented to our hospital from 2005 to 2008 were retrospectively reviewed. All these patients had new diagnosis of bAVM. Univariate (χ(2) test) and multivariate analyses were conducted to assess the angiographic features in patients with and without initial hemorrhagic presentations. A probability value of less than 0.05 was considered statistically significant in each analysis.

RESULTS

In 152 patients with supratentorial AVMs, 70.6% of deep and 52.5% of superficial sbAVMs presented with hemorrhage. The deep location was correlated with initial hemorrhagic presentation in univariate analysis (χ(2)=3.499, p=0.046) but not in the multivariate model (p=0.144). There were 44 sbAVMs with perforating feeders, 39 (88.6%) of which bled at a significantly higher rate than those with terminal feeders (χ(2)=25.904, p=0.000). 87.5% (21/24) of exclusive deep venous drainage presented with hemorrhage, a significantly higher rate than those of the other type of venous drainage (χ(2)=11.099, p=0.004). All 10 patients with both perforating feeders and exclusive deep draining vein presented with initial hemorrhage. Hemorrhagic presentation was correlated with perforating feeders (p=0.000) and exclusive deep draining vein (p=0.007) in multivariate analysis as well.

CONCLUSIONS

Supratentorial bAVMs with perforating feeders and deep venous drainage have a higher risk of hemorrhage. In contrast with many previous reports, AVM location was not associated with hemorrhagic presentation in adjusted analyses. The correlation between deep location and initial hemorrhage in univariate analysis might be caused by the involved perforating feeders and deep draining vein in the deep located AVMs.

Onyx embolization of anterior condylar confluence dural arteriovenous fistula

The anterior condylar confluence (ACC) is a small complex venous structure located medial to the jugular vein and adjacent to the hypoglossal canal. To our knowledge, this is the first report of transvenous Onyx embolization for ACC dural arteriovenous fistula (DAVF). Three patients with ACC DAVF were treated using the Onyx liquid embolic agent with or without detachable coils. Complete angiographic obliteration of the fistulas was achieved in all cases without permanent lower cranial neuropathy. This report suggests that the controlled penetration of Onyx is advantageous in order to obliterate ACC DAVFs with a small amount of embolic material.

Disappearance of a small intracranial aneurysm as a result of vessel straightening and in-stent stenosis following use of an Enterprise vascular reconstruction device

In-stent stenosis after stent-assisted coil embolization is a rare but well-known complication. A 32-year-old woman with an unruptured wide-necked left internal carotid artery (ICA) terminus aneurysm and an ipsilateral very small anterior choroidal artery aneurysm underwent stent-assisted coil embolization for the ICA terminus aneurysm. The 4-month follow-up angiography revealed diffuse in-stent stenosis and disappearance of the untreated anterior choroidal artery aneurysm, retaining the patency of the anterior choroidal artery. To our knowledge, this is the first report to demonstrate the course of in-stent stenosis and disappearance of an untreated small intracranial aneurysm as a result. We report this unique case and discuss the interesting mechanism underlying this phenomenon, and also provide a review of the relevant literature.

Abstract TP89: Ultra Thin Bioabsorbable Polymeric Coating On The Surface Of Coil Materials For Brain Aneurysms Treatment

Purpose: A novel bioactive coil material, which is composed of a bare platinum core coated with an ultrathin layer of 50/50 acidified PGLA was developed for the purpose of accelerating thrombus organization in the treated aneurysms. Experimental aneurysms were with the coils with novel bioactive coating and histologic analysis was performed. The results were compared with the histologic findings observed in the aneurysms treated with a currently available polymeric coil (Matrix II) and bare platinum coils (GDC).

Materials and Methods: A swine aneurysm model, which is designed to perform quantitative analysis of histologic changes induced by the implanted coil materials, was used in this study. The novel bioactive coils, which is composed of a bare platinum core covered with an ultrathin - micron level - polymer coating composed of acidified 50/50 polyglicolic-polylactic acid (PGLA) was implanted in 4 experimental swine aneurysms (group A). Four aneurysms were treated with Matrix II® (group B) and 4 were treated with GDCs (group C). Fourteen days after the implantation, each aneurysm was harvested and histologic analysis of each sample was performed.

Results: Histologic findings showed the most advanced thrombus organization - characterized by dense collagen deposition and prominent fibroblast migration - was observed in aneurysms of group A, followed by group B and C. The most prominent inflammatory reaction adjacent to the coil material at Day 14 was seen in group B, followed by group A and group C. However, group A showed a high degree of collagen organization with little immature thrombus remaining, indicative of late stage aneurysm healing.

Conclusion: The novel bioactive coil material with ultrathin acidified 50/50 PGLA coating may accelerate the thrombus organization in the experimental aneurysms as compared to the currently available coil materials for brain aneurysm treatment.

Abstract TP87: Comparative Analysis of 3-Dimensional Rotation Angiography versus 3-Dimensional Computed Tomography Angiography for Intracranial Aneurysm Treatment Detection and Planning

Introduction: 3D Rotational Angiography (3DRA) is the gold standard for intracranial aneurysm (IA) detection, but is invasive and time consuming. While 3DCTA has shown to be sensitive for IA detection, no published studies have compared 3DRA to 3DCTA in guiding clinical management. Our aim was to compare suggested treatment for IA based on 3DRA and 3DCTA vs actual final treatment and outcome.

Hypothesis: Management recommendations based on blinded review of 3DRA and 3DCTA for IA do not differ significantly.

Methods: Prospective blinded review of contemporaneous 3DRA and 3DCTA was performed for patients with suspected IA. Two interventionalists and two neuroradiologists performed blinded, prospective review of 3DRA or 3DCTA, respectively. IA size, location, and morphology were assessed. After IA characterization, each observer independently recommended optimal therapy (conservative, coil, surgery, combined/other) while blinded to other reviewers’ decisions. Findings were analyzed with Spearman, and agreement coefficient 1 (AC1) inter-rater reliability statistics.

Results: 41/52 enrolled patients had IA confirmed by 3DRA (52 IA total). 50/52 (96%) IA were initially identified by 3DCTA (both false negatives seen retrospectively). Average IA sac and neck size measured by 3DRA and 3DCTA correlated closely (p<0.01) and were 9.8 and 5.0 mm vs 9.5 and 4.5 mm, respectively. Treatment recommendations by reviewers for 3DRA vs 3DCTA correlated very strongly (AC1= 0.77), as did reader recommendations within a modality (3DRA, AC1=0.66; 3DCTA, AC1=0.79). For 39/52 (75%) of IA, majority consensus for all readers was reached (3/4 or 4/4 reviewers), which correlated well with final executed treatments (95%).

Conclusions: Recommendations for IA treatment based on 3DCTA correlate closely with those based on 3DRA, as well as with actual treatment in a majority of patients. 3DCTA holds promise as a primary imaging tool for IA detection and clinical decision making.

Abstract WMP28: Follow-up of Large Intracranial Aneurysms Indicates Growth Frequency Varies According to Location and Size

Background: Although treatment is recommended for unruptured large aneurysms (≥7mm), which have higher rupture risk, in practice some aneurysms remain under observation due to a patient’s medical history or age. Detailed data about aneurysm growth during follow-up is limited. In this study, we aim to investigate growth in large aneurysms by reviewing the unruptured aneurysms cases which were followed in our center.

Hypothesis: The growth of large unruptured aneurysms varies according to aneurysm characteristics and patient medical history.

Method: A retrospective review of patient records based on unruptured aneurysms diagnosed in our center from 2005 to 2011 was performed. Large unruptured aneurysms which had more than one CTA examination separated by at least 3 months were included. Aneurysm characteristics, patient information, and medical history were recorded. Univariate and multivariate logistic regression were used to analyze aneurysm growth.

Results: From a total of 410 unruptured aneurysms followed in our center, 50 large aneurysms (41 females, 9 males; age 67.3±12.6 years) were included: 42 aneurysms with initial size 7-12.9 mm, 7 aneurysms 13-23.9 mm, and 1 aneurysm ≥24 mm. During the average 25.6 month follow-up, 15 (30%) aneurysms enlarged and 35 (70%) were unchanged. The growth frequency of aneurysms located in ICA, MCA, ACA, BA was 40%, 22%, 20% and 17%, respectively. The growth frequency of aneurysms of sizes 7-12.9 mm, 13-23.9 mm and ≥24 mm was 23.8%, 71.4% and 0, respectively. Using univariate logistic regression analysis, duration of follow-up (P=0.023), and history of ischemic stroke (P=0.027) were associated with growth. Multivariate logistic regression showed only duration of follow-up as a risk factor for growth (OR, 1.056 per month; 95% CI 1010 to 1.104; P=0.016). Only one aneurysm (ICA) ruptured in the follow-up (70 months), resulting in a rupture rate of 6.7% (1/15) enlarged aneurysms (0/35 unchanged aneurysms).

Conclusion: A large percentage of aneurysms selected for observation grew, and growth frequency varied according to aneurysm location and size. A larger, future study may identify additional factors associated with growth, including ones specific to aneurysm characteristics like location and initial size.

Abstract WP89: Hemodynamic Differences Found in Ruptured and Unruptured Aneurysms - Quantitative Comparison of 41 Cases from a Single Location

Introduction: Brain aneurysm growth and rupture has been reported to relate to hemodynamic properties. To understand the characteristics of high rupture risk blood flow, research has studied flow differences between ruptured and unruptured aneurysms. Although it is known that flow characteristics also vary between different aneurysm locations, due to the rarity of data for ruptured cases, previous reports which showed differences between ruptured and unruptured aneurysms have relied on the inclusion of cases from multiple locations for the comparison.

Hypothesis: Our aim is to test the hypothesis that hemodynamic differences between ruptured and unruptured cases can be found in aneurysms at the same location.

Methods: To include sufficient ruptured and unruptured cases, aneurysms located at the internal carotid artery-ophthalmic artery, the most common aneurysms in our center, were analyzed. A total of 41 (12 ruptured and 29 unruptured) cases treated from January 2004 to August 2011 were included. Aneurysms were studied using patient-specific hemodynamic analysis. Flow changes in different aneurysm regions and their association with rupture were analyzed quantitatively. Statistical methods including multivariate test and paired t-tests were used to investigate the flow differences between ruptured and unruptured groups.

Results: Concentrated high blood flow pulsatility was discovered in ruptured aneurysms. In contrast, the blood flow pulsatility was found to be lower and increased gradually from the neck to dome in unruptured aneurysms. Pulsatility index at regions of neck, body, and dome averaged 1.5, 1.7, and 1.5 for ruptured cases, and 1.0, 1.2, and 1.3 for unruptured cases. Quantitative comparisons of inflow and outflow that analyzed the temporal characteristics of the flow showed that significant changes within the aneurysm sac may be a key indicator related to aneurysm rupture risk (P<0.05).

Conclusions: The different hemodynamic characteristics between ruptured and unruptured cases found in our study suggest that the high pulsatility and the relationship between inflow and outflow may be useful to characterize rupture risk for aneurysms at the same location.

Abstract WP90: Immunohistochemical Analysis Of A Ruptured Basilar Top Aneurysm Treated With Coil Embolization In 1990

Purpose: A ruptured basilar top aneurysm was treated with pre-market GDC in 1990. The fourteenth patient since the initial clinical use of the GDC survived the subarachnoid hemorrhage and deceased in 2012 due to unrelated medical condition. Immunohistochemical analysis of the aneurysm was performed.

Materials and Methods: A 61 year old female who suffered SAH due to a ruptured basilar top aneurysm majoring 6mm in largest diameter was treated with GDC in 1990. The patient survived the SAH without any neurological deficit, and the last angiogram performed in 1996 showed complete obliteration. The patient recently deceased in 2012 due to unrelated medical condition, and autopsy was performed. The aneurysm was removed with the surrounding tissue, fixed and embedded in paraffin. Histologic analysis using H&E staining, Masson Trichrome staining, alfa smooth muscle actine (αSMA) staining as well as factor VIII staining was performed.

Results: The gross findings showed no adhesion between the treated aneurysm and the adjacent brain tissue. The orifice of the aneurysm was completely covered by a layer of neointima, and patency of bilateral P1 perforators was confirmed. Microscopic findings showed a prominent collagen deposition with minimal cellular component in the aneurysm. A thick layer of neointima covering the orifice of the aneurysm was composed of a layer of thick collagenous tissue and a layer of SMA positive sub intimal tissue. There was no major histologic change observed in the adjacent brain tissue such as cerebral peduncles.

Conclusion: A histologic / immunohistochemical analysis of a ruptured basilar top aneurysm which was treated 22 years ago was performed. A neointima covering the orifice of the aneurysm was composed of a thick layer of collagenous tissue and a layer of SMA positive subintimal tissue. Patency of the perforating arteries from the bilateral P1 segment was confirmed, and no major histologic change was seen in the adjacent brain tissue.

Abstract TP82: The Growth of Small, Asymptomatic, Unruptured Intracranial Aneurysms with no History of SAH -Different Risk Factors Associated with Single and Multiple Aneurysms

Introduction: The International Study on Unruptured Intracranial Aneurysms suggests that small (<7mm), asymptomatic, unruptured intracranial aneurysms (UIA) in patients with no history of subarachnoid hemorrhage (SAH) should be managed conservatively. Recent research has independently shown considerable variation in the rupture risk of small UIA. As enlargement may indicate increased risk of rupture, the factors related to UIA growth may also influence rupture risk. Information about small UIA growth is limited and heterogeneous due to limited follow-up data.

Hypothesis: Growth factors for small UIA vary between subset groups.

Methods: A retrospective study was performed based on a total of 508 patients diagnosed with UIA from 2005-2010 in our center. 235 patients with asymptomatic, small UIA and no history of SAH were monitored with high resolution 3D CTA. Patient medical history and aneurysm characteristics (size, growth, location and multiplicity) were analyzed. Multiple logistic regression analysis and the Hosmer-Lemeshow statistic were used to identify the factors associated with growth. The Student’s t-test was applied to compare the aneurysm growth rate between subset groups.

Results: A total of 319 UIA were included with follow-up durations of 29.2 20.0 months. 42 UIA increased in size during the follow-up. 5 UIA grew to become ≥ 7 mm (within 38.2±18.3 months). A trend of higher growth rates was found in single aneurysms than in multiple aneurysms (P=0.07). History of stroke was the only factor associated with single aneurysm growth (P=0.03). The number of aneurysms (P=0.014), aneurysms located within the posterior circulation (P=0.023), and patient history of transient ischemic attack (P=0.032) were related to multiple aneurysm growth.

Conclusion: We found that multiple small aneurysms were more likely to grow, especially those at posterior circulation. Although single aneurysms have a lower risk of growth, a trend of higher growth rates was found.

Abstract TP57: Post-Procedure ASPECTS Score Incorporating Parenchymal Hyperdensity Correlates with Clinical Outcome After Endovascular Therapy

Introduction: Noncontrast head CT (NCHCT) is routinely acquired after endovascular therapy for acute stroke to evaluate for early complications, yet residual contrast staining is common. We hypothesized that modification of ASPECTS scoring to include any region involved with either abnormal hypodensity or hyperdensity may accurately correlate with subsequent clinical outcomes.

Methods: Consecutive patients with M1 or M2 MCA occlusion treated over a 2-year period were analyzed. All patients that underwent immediate post-procedure CT and MRI within 24 hours were included. Clinical and radiological data was reviewed. A modified ASPECTS scoring system was applied that considered areas of parenchymal hyperdensity as also being involved by ischemic injury.

Results: A total of 30 patients were identified, including 14 men and 16 women with an average age of 64.5 years old. Endovascular recanalization procedures were performed with either the MERCI and\or Penumbra devices. Comparison of the modified ASPECTS score on the post-procedure CT with the post procedure ASPECTS score on DWI MRI demonstrated good correlation with no statistically significant difference (p = .260). On the immediate post-procedure CT, patients with a modified ASPECTS score greater than or equal to 7 versus those with a score less than 7 had an average NIHSS reduction at discharge of 7.3 versus 2.2 (p=.014) and 90 day modified Rankin score of 2.3 versus 4.5 (p=.002). Presence of parenchymal hyperdensity versus no hyperdensity on the post-procedure CT alone did not correlate with clinical outcomes using NIHSS or 90 day modified Rankin score (p=.120 and p=.069 respectively).

Conclusions: Evaluation of the immediate post procedure NCHCT using a modified ASPECTS scoring system, which incorporates any parenchymal hyperdensity, may be useful to judge clinical response to the intervention. Patients with modified ASPECT score greater than or equal to 7 did significantly better than those with lower scores. Presence of parenchymal hyperdensity alone did not correlate with clinical outcomes.

Disappearance of a small intracranial aneurysm as a result of vessel straightening and in-stent stenosis following use of an Enterprise vascular reconstruction device

In-stent stenosis after stent-assisted coil embolization is a rare but well-known complication. A 32-year-old woman with an unruptured wide-necked left internal carotid artery (ICA) terminus aneurysm and an ipsilateral very small anterior choroidal artery aneurysm underwent stent-assisted coil embolization for the ICA terminus aneurysm. The 4-month follow-up angiography revealed diffuse in-stent stenosis and disappearance of the untreated anterior choroidal artery aneurysm, retaining the patency of the anterior choroidal artery. To our knowledge, this is the first report to demonstrate the course of in-stent stenosis and disappearance of an untreated small intracranial aneurysm as a result. We report this unique case and discuss the interesting mechanism underlying this phenomenon, and also provide a review of the relevant literature.