Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics

Cebral, Juan R.; Mut, Fernando; Chung, Bong Jae; Spelle, Laurent; Moret, Jacques; Nijnatten, Fred van; Ruijters, Daniël

doi:10.3174/ajnr.a5158

Cited by 10 publications

(6 citation statements)

References 16 publications

(16 reference statements)

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“…The catheter tip was positioned approximately 15 cm upstream of the aneurysm. A projection was chosen to clearly discern the aneurysm and its neck from the parent vessel while avoiding vascular overlap in the feeding artery [ 8 ]. The flow pump was temporarily switched off to avoid movement artifact during VasoCT (220° rotation, 617 single frames at a frame rate of 30/s, 22 cm detector field of view and 512 acquisition matrix).…”

Section: Methodsmentioning

confidence: 99%

Intra-aneurysmal flow disruption after implantation of the Medina® Embolization Device depends on aneurysm neck coverage

et al. 2018

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Background and purposeFlow disruption achieved by braided intrasaccular implants is a novel treatment strategy for cerebrovascular aneurysms. We hypothesized that the degree of intra-aneurysmal flow disruption can be quantified in vitro and is influenced by device position across the aneurysm neck. We tested this hypothesis using the Medina® Embolization Device (MED).MethodsTen different patient-specific elastic vascular models were manufactured. Models were connected to a pulsatile flow circuit, filled with a blood-mimicking fluid and treated by two operators using a single MED. Intra-aneurysmal flow velocity was measured using conventional and high-frequency digital subtraction angiography (HF-DSA) before and after each deployment. Aneurysm neck coverage by the implanted devices was assessed with flat detector computed tomography on a three-point Likert scale.ResultsA total of 80 individual MED deployments were performed by the two operators. The mean intra-aneurysmal flow velocity reduction after MED implantation was 33.6% (27.5–39.7%). No significant differences in neck coverage (p = 0.99) or flow disruption (p = 0.84) were observed between operators. The degree of flow disruption significantly correlated with neck coverage (ρ = 0.42, 95% CI: 0.21–0.59, p = 0.002) as well as with neck area (ρ = -0,35, 95% CI: -0.54 –-0.13, p = 0.024). On multiple regression analysis, both neck coverage and total neck area were independent predictors of flow disruption.ConclusionsThe degree of intra-aneurysmal flow disruption after MED implantation can be quantified in vitro and varies considerably between different aneurysms and different device configurations. Optimal device coverage across the aneurysm neck improves flow disruption and may thus contribute to aneurysm occlusion.

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Section: Methodsmentioning

confidence: 99%

Intra-aneurysmal flow disruption after implantation of the Medina® Embolization Device depends on aneurysm neck coverage

et al. 2018

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“…[4][5][6][7] However, the growth in neuro-endovascular treatment has rekindled interest in the use of angiographic techniques for flow assessment in various pathologies. [8][9][10][11][12][13][14] The treatment of aneurysms with flow diverters is particularly amenable to such analysis because (a) the reduction of intraaneurysmal flow remains a central hypothesis of treatment success; (b) flow diversion does not require (dense) intra-saccular device implantation, thus allowing for X-ray visualization of contrast transport within the aneurysm; and (c) instead of the need for extraction of absolute flow parameters, the change in intraaneurysmal contrast transport from pre-device implantation to post-device implantation can potentially be used to predict aneurysm occlusion. Current angiographic methods used to generate predictive values of flow diversion success are generally based on grading scales, 15 quantification of aneurysmal time-density curves (TDC), 8,12,16 or optical flow 10,14 methods.…”

Section: Introductionmentioning

confidence: 99%

Angiographic assessment of the efficacy of flow diverter treatment for cerebral aneurysms

et al. 2019

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Background The recent growth of neuro-endovascular treatment has rekindled interest in the use of angiographic techniques for flow assessment. Aneurysm treatment with flow diverters is particularly amenable to such analysis. We analyze contrast time–density curves — recorded within aneurysms before (pre) and immediately after (post) flow diverter implantation to estimate six-month treatment outcomes. Methods Fifty-six patients with 65 aneurysms were treated with flow diverters at two institutions. A region of interest was drawn around the aneurysm perimeter in image sequences taken both pre and post angiography, and the temporal variation in grayscale intensity within the aneurysm (time–density curve) was recorded. Eleven parameters were quantified from each time–density curve. Aneurysm occlusion status was recorded six months post treatment. The change in parameters from pre to post treatment was statistically evaluated between aneurysm occluded and non-occluded groups. Results Of the 11 parameters, eight were significantly different before and immediately after flow diversion. Considering the entire data set, none of the parameters was statistically different between the occluded and non-occluded groups. However, subgroup analyses showed that four variables were significantly different between the aneurysm occluded and non-occluded groups. The sensitivity of these variables to predict aneurysm occlusion at six months ranged from 60% to 89%, while the specificity ranged from 55% to 70%. Conclusions Device-induced intra-aneurysmal flow alterations quantified by simple aneurysmal time–density curves can potentially be used to predict long-term outcomes of flow diversion. Large multi-center studies will be required to confirm these findings. Patient-to-patient variability in coagulation may need to be incorporated for clinically relevant predictive values.

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“…Basic parameters of aneurysmal concentration-time curves (aC-T curves) such as slopes or mean-transit-time calculations, calculations of variations in image intensity throughout the aneurysm or at the inflow and outflow zones, or curve-fitting of gamma-variate, single-and double-exponential, polynomial, or lagged-normal models to aC-T curves have been used to derive quantities representative of intraneurysmal flow. 31,32,[41][42][43][44][45][46][47][48][49] Derived quantities are then employed to quantify device efficacy by considering the changes in the quantities pre-and post-treatment.…”

Section: Introductionmentioning

confidence: 99%

In vitro angiographic comparison of the flow-diversion performance of five neurovascular stents

et al. 2017

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Background and purpose Data differentiating flow diversion properties of commercially available low- and high-porosity stents are limited. This in vitro study applies angiographic analysis of intra-aneurysmal flow to compare the flow-diversion performance of five neurovascular devices in idealized sidewall and bifurcation aneurysm models. Methods Five commercial devices (Enterprise, Neuroform, LVIS, FRED, and Pipeline) were implanted in silicone sidewall and bifurcation aneurysm models under physiological average flow of blood analog fluid. High-speed angiographic images were acquired pre- and post-device implantation and contrast concentration-time curves within the aneurysm were recorded. The curves were quantified with five parameters to assess changes in contrast transport, and thus aneurysm hemodynamics, due to each device. Results Inter-device flow-diversion performance was more easily distinguished in the sidewall model than the bifurcation model. There were no obvious overall statistical trends in the bifurcation parameters but the Pipeline performed marginally better than the other devices. In the sidewall geometry, overall evidence suggests that the LVIS performed better than the Neuroform and Enterprise. The Pipeline and FRED devices were statistically superior to the three stents and Pipeline was superior to FRED in all sidewall parameters evaluated. Conclusions Based on this specific set of experiments, lower-porosity flow diverters perform significantly better in reducing intra-aneurysmal flow activity than higher-porosity stents in sidewall-type geometries. The LVIS device is potentially a better flow diverter than the Neuroform and Enterprise devices, while the Pipeline is potentially better than the FRED.

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Understanding Angiography-Based Aneurysm Flow Fields through Comparison with Computational Fluid Dynamics

Cited by 10 publications

References 16 publications

Intra-aneurysmal flow disruption after implantation of the Medina® Embolization Device depends on aneurysm neck coverage

Intra-aneurysmal flow disruption after implantation of the Medina® Embolization Device depends on aneurysm neck coverage

Angiographic assessment of the efficacy of flow diverter treatment for cerebral aneurysms

In vitro angiographic comparison of the flow-diversion performance of five neurovascular stents

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