Inflow Jet Patterns of Unruptured Cerebral Aneurysms Based on the Flow Velocity in the Parent Artery: Evaluation Using 4D Flow MRI

Futami, Kazuya; Kitabayashi, Tamotsu; Sano, Hiroki; Misaki, Kouichi; Uchiyama, Naoyuki; Ueda, Fumiaki; Nakada, Mitsutoshi

doi:10.3174/ajnr.a4704

Cited by 14 publications

(11 citation statements)

References 31 publications

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“…The results of our study concur with Futami et al's 18 and Khan et al's studies, 11 which demonstrated that local WSS had a significant association with AWE, as shown in figures 4A and 5A,B. These studies reported that when the aneurysm wall was exposed to low WSS, the vascular permeability may be increased, which manifested as AWE.…”

Section: Association Between Wss and Awesupporting

confidence: 92%

“…The inflow jet pattern was defined as concentrated (figure 3A), diffuse (figure 3B) and unvisualised 18 -concentrated inflow jet: a bundle of inflow streamlines intruding into the aneurysm dome with a dispersion of <20% of the width of the streamline bundle at the aneurysm orifice; diffuse inflow jet: inflow streamlines intruding into the aneurysm dome with a dispersion of >20% of the width of the streamline bundle at the aneurysm orifice and unvisualized inflow jet: no inflow streamlines into the aneurysm. 18 Vorticity=abs (ζx, ζy, ζz) (with ζx=δw/δy−δv/δz, ζy=δu/ δz−δw/δx, ζz = δv/δx−δu/δy), where u, v and w are the vector components of the velocity in the segmented 3D space and x, y and z are the directions in the Cartesian k-space. 23 The segmentation of the IA (figure 3C) and the vorticity calculations (figure 3D) were performed using a custombuilt software programmed in MATLAB and Python.…”

Section: Open Accessmentioning

confidence: 99%

“…Association between inflow jet pattern and AWE Previous studies have revealed that inflow jet patterns may help stratify the risk of aneurysm rupture. 18 Futami et al had reported four classifications (concentrated, diffuse, neck-limited and unvisualised) of the inflow jet pattern in IAs using 4D-flow MRI. 18 In our study, because the small number of patients in the neck-limited and unvisualised groups, we merged the two into the 'unvisualised group'.…”

Section: Association Between Wss and Awementioning

confidence: 99%

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Associations between haemodynamics and wall enhancement of intracranial aneurysm

et al. 2021

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Background and purposePrevious studies have reported about inflammation processes (IPs) that play important roles in aneurysm formation and rupture, which could be driven by blood flow. IPs can be identified using aneurysmal wall enhancement (AWE) on high-resolution black-blood MRI (BB-MRI) and blood flow haemodynamics can be demonstrated by four-dimensional-flow MRI (4D-flow MRI). Thus, this study investigated the associations between AWE and haemodynamics in unruptured intracranial aneurysms (IA) by combining 4D-flow MRI and high-resolution BB-MRI.Materials and methodsBetween April 2014 and October 2017, 48 patients with 49 unruptured IA who underwent both 4D-flow MRI and high-resolution BB-MRI were retrospectively included in this study. The haemodynamic parameters demonstrated using 4D-flow MRI were compared between different AWE patterns using the Kruskal-Wallis test and ordinal regression.ResultsThe results of Kruskal-Wallis test showed that the average wall shear stress in the IA (WSSavg-IA), maximum through-plane velocity in the adjacent parent artery, inflow jet patterns and the average vorticity in IA (vorticityavg-IA) were significantly associated with the AWE patterns. Ordinal regression analysis identified WSSavg-IA (p=0.002) and vorticityavg-IA (p=0.033) as independent predictors of AWE patterns.ConclusionA low WSS and low average vorticity were independently associated with a high AWE grade for IAs larger than 4 mm. Therefore, WSS and average vorticity could predict AWE and circumferential AWE.

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Section: Association Between Wss and Awesupporting

confidence: 92%

Section: Open Accessmentioning

confidence: 99%

Section: Association Between Wss and Awementioning

confidence: 99%

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Associations between haemodynamics and wall enhancement of intracranial aneurysm

et al. 2021

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“…Other research groups have reported flow conditions at the aneurysm neck with an in vivo hemodynamic assessment by using a 1.5T MR scanner and with an emphasis on the measurability and influential factors of neck flow. [12][13][14] Nevertheless, to our knowledge, few reports have investigated the relationship between the ostium and FD treatment response. 15,16 We hypothesized that different FD treatment responses were related to aneurysm features, and our study focused on the aneurysm geometries and hemodynamics at the ostium.…”

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confidence: 99%

Large Neck and Strong Ostium Inflow as the Potential Causes for Delayed Occlusion of Unruptured Sidewall Intracranial Aneurysms Treated by Flow Diverter

Su¹,

Reymond²,

Brina³

et al. 2020

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: Flow diverter-induced hemodynamic change plays an important role in the mechanism of intracranial aneurysm occlusion. Our aim was to explore the relationship between aneurysm features and flow-diverter treatment of unruptured sidewall intracranial aneurysms. MATERIALS AND METHODS: MR imaging, 4D phase-contrast, was prospectively performed before flow diverter implantation in each patient with unruptured intracranial aneurysm. Two postprocedure follow-ups were scheduled at 6 and 12 months. Responses were grouped according to whether the aneurysms were occluded or remnant. Preprocedural aneurysm geometries and ostium hemodynamics in 38 patients were compared between the 2 groups at 6 and 12 months. Receiver operating characteristic curve analyses were performed for significant geometric and hemodynamic continuous parameters. RESULTS: After the 6-month assessment, 21 of 41 intracranial aneurysms were occluded, and 9 additional aneurysms were occluded at 12 months. Geometrically, the ostium maximum diameter was significantly larger in the remnant group at 6 and 12 months (both P , .001). Hemodynamically, the proximal inflow zone was more frequently observed in the remnant group at 6 months. Several preprocedural ostium hemodynamic parameters were significantly higher in the remnant group. As a prediction for occlusion, the areas under the curve of the ostium maximum diameter (for 6 and 12 months), systolic inflow rate ratio (for 6 months), and systolic inflow area (for 12 months) reached 0.843, 0.883, 0.855, and 0.860, respectively. CONCLUSIONS: Intracranial aneurysms with a large ostium and strong ostium inflow may need a longer time for occlusion. Preprocedural 4D flow MR imaging can well illustrate ostium hemodynamics and characterize aneurysm treatment responses.

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“…[1][2][3][4]7,8 However, CFD analysis is based on assumptions and approximations regarding blood properties, vessel wall compliance, and flow conditions, [1][2][3][4] and the location of the vortex core line depends on mathematic definitions. 8 Although 4D flow MR imaging, based on time-resolved 3D cine phase-contrast MR imaging techniques, has been used to evaluate the hemodynamics in human cerebral aneurysms, [9][10][11][12] the visualization of aneurysm vortex cores with this imaging technique has not been reported. Identification of vortex cores on 4D flow MR imaging may be an alternative to CFD analysis of aneurysm models and may lead to new insights into the role of vortex cores in aneurysm behavior.…”

mentioning

confidence: 99%

Identification of Vortex Cores in Cerebral Aneurysms on 4D Flow MRI

Futami

Uno

Misaki

et al. 2019

AJNR Am J Neuroradiol

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BACKGROUND AND PURPOSE: The complexity and instability of the vortex flow in aneurysms are factors related to the rupture risk of unruptured cerebral aneurysms. We identified aneurysm vortex cores on 4D flow MR imaging and examined the relationship of these factors with the characteristics of cerebral aneurysms. MATERIALS AND METHODS: We subjected 40 aneurysms (37 unruptured, 3 ruptured) to 4D flow MR imaging. We visualized streamlines with velocities below the threshold-that is, a percentage value of the aneurysm maximum inflow velocity-and progressively decreased the threshold to identify vortex cores as thin, streamline bundles with minimum velocities. Complexity and stability were compared in aneurysms with a smooth surface and those with blebs or daughter sacs. RESULTS: The threshold for visualizing vortex cores ranged from 3% to 13% of the maximum inflow velocity. Vortex cores could be visualized in 38 aneurysms; in 2, they were not visualized through the cardiac cycle. A simple flow pattern (single vortex core) was identified in 27 aneurysms; the other 13 exhibited a complex flow pattern. The cores were stable in 32 and unstable in 8 aneurysms. Significantly more aneurysms with-than-without blebs or daughter sacs had a complex flow pattern (P = .006). Of the 3 ruptured aneurysms, 1 aneurysm had an unstable vortex core; in the other 2, the vortex core was not visualized. CONCLUSIONS: The identification of vortex cores on 4D flow MR imaging may help to stratify the rupture risk of unruptured cerebral aneurysms.

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Inflow Jet Patterns of Unruptured Cerebral Aneurysms Based on the Flow Velocity in the Parent Artery: Evaluation Using 4D Flow MRI

Abstract: BACKGROUND AND PURPOSE:Inflow jet characteristics may be related to aneurysmal bleb formation and rupture. We investigated the visualization threshold on the basis of the flow velocity in the parent artery to classify the inflow jet patterns observed on 4D flow MR imaging.

Cited by 14 publications

References 31 publications

Associations between haemodynamics and wall enhancement of intracranial aneurysm

Associations between haemodynamics and wall enhancement of intracranial aneurysm

Large Neck and Strong Ostium Inflow as the Potential Causes for Delayed Occlusion of Unruptured Sidewall Intracranial Aneurysms Treated by Flow Diverter

Identification of Vortex Cores in Cerebral Aneurysms on 4D Flow MRI

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