Recent high-resolution computational fluid dynamics (CFD) studies have detected persistent flow instability in intracranial aneurysms (IAs) that was not observed in previous in silico studies. These flow fluctuations have shown incidental association with rupture in a small aneurysm dataset. The aims of this study are to explore the capabilities and limitations of a commercial cfd solver in capturing such velocity fluctuations, whether fluctuation kinetic energy (fKE) as a marker to quantify such instability could be a potential parameter to predict aneurysm rupture, and what geometric parameters might be associated with such fluctuations. First, we confirmed that the second-order discretization schemes and high spatial and temporal resolutions are required to capture these aneurysmal flow fluctuations. Next, we analyzed 56 patient-specific middle cerebral artery (MCA) aneurysms (12 ruptured) by transient, high-resolution CFD simulations with a cycle-averaged, constant inflow boundary condition. Finally, to explore the mechanism by which such flow instabilities might arise, we investigated correlations between fKE and several aneurysm geometrical parameters. Our results show that flow instabilities were present in 8 of 56 MCA aneurysms, all of which were unruptured bifurcation aneurysms. Statistical analysis revealed that fKE could not differentiate ruptured from unruptured aneurysms. Thus, our study does not lend support to these flow instabilities (based on a cycle-averaged constant inflow as opposed to peak velocity) being a marker for rupture. We found a positive correlation between fKE and aneurysm size as well as size ratio. This suggests that the intrinsic flow instability may be associated with the breakdown of an inflow jet penetrating the aneurysm space.

References

References
1.
Vlak
,
M. H.
,
Algra
,
A.
,
Brandenburg
,
R.
, and
Rinkel
,
G. J.
,
2011
, “
Prevalence of Unruptured Intracranial Aneurysms, With Emphasis on Sex, Age, Comorbidity, Country, and Time Period: A Systematic Review and Meta-Analysis
,”
Lancet Neurol.
,
10
(
7
), pp.
626
636
.
2.
Wiebers
,
D. O.
,
2003
, “
Unruptured Intracranial Aneurysms: Natural History, Clinical Outcome, and Risks of Surgical and Endovascular Treatment
,”
Lancet
,
362
(
9378
), pp.
103
110
.
3.
Cebral
,
J. R.
,
Mut
,
F.
,
Weir
,
J.
, and
Putman
,
C. M.
,
2011
, “
Association of Hemodynamic Characteristics and Cerebral Aneurysm Rupture
,”
AJNR Am. J. Neuroradiol.
,
32
(
2
), pp.
264
270
.
4.
Jou
,
L. D.
,
Lee
,
D. H.
,
Morsi
,
H.
, and
Mawad
,
M. E.
,
2008
, “
Wall Shear Stress on Ruptured and Unruptured Intracranial Aneurysms at the Internal Carotid Artery
,”
AJNR. Am. J. Neuroradiol.
,
29
(
9
), pp.
1761
1767
.
5.
Shojima
,
M.
,
Oshima
,
M.
,
Takagi
,
K.
,
Torii
,
R.
,
Hayakawa
,
M.
,
Katada
,
K.
,
Morita
,
A.
, and
Kirino
,
T.
,
2004
, “
Magnitude and Role of Wall Shear Stress on Cerebral Aneurysm: Computational Fluid Dynamic Study of 20 Middle Cerebral Artery Aneurysms
,”
Stroke
,
35
(
11
), pp.
2500
2505
.
6.
Xiang
,
J.
,
Natarajan
,
S. K.
,
Tremmel
,
M.
,
Ma
,
D.
,
Mocco
,
J.
,
Hopkins
,
L. N.
,
Siddiqui
,
A. H.
,
Levy
,
E. I.
, and
Meng
,
H.
,
2011
, “
Hemodynamic-Morphologic Discriminants for Intracranial Aneurysm Rupture
,”
Stroke
,
42
(
1
), pp.
144
152
.
7.
Valen-Sendstad
,
K.
,
Piccinelli
,
M.
, and
Steinman
,
D. A.
,
2014
, “
High-Resolution Computational Fluid Dynamics Detects Flow Instabilities in the Carotid Siphon: Implications for Aneurysm Initiation and Rupture?
,”
J. Biomech.
,
47
(
12
), pp.
3210
3216
.
8.
Valen-Sendstad
,
K.
, and
Steinman
,
D. A.
,
2014
, “
Mind the Gap: Impact of Computational Fluid Dynamics Solution Strategy on Prediction of Intracranial Aneurysm Hemodynamics and Rupture Status Indicators
,”
AJNR. Am. J. Neuroradiol.
,
35
(
3
), pp.
536
543
.
9.
Ferguson
,
G. G.
,
1970
, “
Turbulence in Human Intracranial Saccular Aneurysms
,”
J. Neurosurg.
,
33
(
5
), pp.
485
497
.
10.
Olinger
,
C. P.
, and
Wasserman
,
J. F.
,
1977
, “
Electronic Stethoscope for Detection of Cerebral Aneurysm, Vasospasm, and Arterial Disease
,”
Surg. Neurol.
,
8
(
4
), pp.
298
312
.
11.
Sekhar
,
L. N.
, and
Wasserman
,
J. F.
,
1984
, “
Noninvasive Detection of Intracranial Vascular Lesions Using an Electronic Stethoscope
,”
J. Neurosurg.
,
60
(
3
), pp.
553
559
.
12.
Stehbens
,
W. E.
,
1975
, “
Flow in Glass Models of Arterial Bifurcations and Berry Aneurysms at Low Reynolds Numbers
,”
Q. J. Exp. Physiol. Cogn. Med. Sci.
,
60
(
3
), pp.
181
192
.
13.
Ford
,
M.
,
Nikolov
,
H.
,
Milner
,
J. S.
,
Lownie
,
S. P.
,
DeMont
,
E. M.
,
Kalata
,
W.
,
Lowth
,
F.
,
Holdsworth
,
D. W.
, and
Steinman
,
D. A.
,
2008
, “
PIV-Measured Versus CFD-Predicted Flow Dynamics in Anatomically Realistic Cerebral Aneurysm Models
,”
ASME J. Biomech. Eng.
,
130
(
2
), p. 021015.
14.
Roach
,
M. R.
,
Scott
,
S.
, and
Ferguson
,
G. G.
,
1972
, “
The Hemodynamic Importance of the Geometry of Bifurcations in the Circle of Willis (Glass Model Studies)
,”
Stroke
,
3
(
3
), pp.
255
267
.
15.
Simpkins
,
T.
, and
Stehbens
,
W.
,
1973
, “
Vibrational Behavior of Arterial Aneurysms
,”
Lett. Appl. Eng. Sci.
,
1
, pp.
85
100
.
16.
Ford
,
M. D.
, and
Piomelli
,
U.
,
2012
, “
Exploring High Frequency Temporal Fluctuations in the Terminal Aneurysm of the Basilar Bifurcation
,”
ASME J. Biomech. Eng.
,
134
(
9
), p.
091003
.
17.
Valen-Sendstad
,
K.
,
Mardal
,
K. A.
, and
Steinman
,
D. A.
,
2013
, “
High-Resolution CFD Detects High-Frequency Velocity Fluctuations in Bifurcation, but not Sidewall, Aneurysms
,”
J. Biomech.
,
46
(
2
), pp.
402
407
.
18.
Antiga
,
L.
, and
Steinman
,
D. A.
,
2009
, “
Rethinking Turbulence in Blood
,”
Biorheology
,
46
(
2
), pp.
77
81
.
19.
Khan
,
M. O.
,
Valen-Sendstad
,
K.
, and
Steinman
,
D. A.
,
2015
, “
Narrowing the Expertise Gap for Predicting Intracranial Aneurysm Hemodynamics: Impact of Solver Numerics Versus Mesh and Time-Step Resolution
,”
Am. J. Neuroradiol.
,
36
(
7
), pp.
1310
1316
.
20.
Dhar
,
S.
,
Tremmel
,
M.
,
Mocco
,
J.
,
Kim
,
M.
,
Yamamoto
,
J.
,
Siddiqui
,
A. H.
,
Hopkins
,
L. N.
, and
Meng
,
H.
,
2008
, “
Morphology Parameters for Intracranial Aneurysm Rupture Risk Assessment
,”
Neurosurgery
,
63
(
2
), pp.
185
196; Discussion 196–187
.
21.
Antiga
,
L.
, and
Steinman
,
D. A.
,
2004
, “
Robust and Objective Decomposition and Mapping of Bifurcating Vessels
,”
IEEE Trans. Med. Imaging
,
23
(
6
), pp.
704
713
.
22.
Antiga
,
L.
,
Piccinelli
,
M.
,
Botti
,
L.
,
Ene-Iordache
,
B.
,
Remuzzi
,
A.
, and
Steinman
,
D. A.
,
2008
, “
An Image-Based Modeling Framework for Patient-Specific Computational Hemodynamics
,”
Med. Biol. Eng. Comput.
,
46
(
11
), pp.
1097
1112
.
23.
Stock
,
K. W.
,
Wetzel
,
S. G.
,
Lyrer
,
P. A.
, and
Radu
,
E. W.
,
2000
, “
Quantification of Blood Flow in the Middle Cerebral Artery With Phase-Contrast MR Imaging
,”
Eur. Radiol.
,
10
(
11
), pp.
1795
1800
.
24.
Oka
,
S.
, and
Nakai
,
M.
,
1987
, “
Optimality Principle in Vascular Bifurcation
,”
Biorheology
,
24
(
6
), pp.
737
751
.
25.
Valen-Sendstad
,
K.
,
Mardal
,
K. A.
,
Mortensen
,
M.
,
Reif
,
B. A.
, and
Langtangen
,
H. P.
,
2011
, “
Direct Numerical Simulation of Transitional Flow in a Patient-Specific Intracranial Aneurysm
,”
J. Biomech.
,
44
(
16
), pp.
2826
2832
.
26.
Enzmann
,
D. R.
,
Ross
,
M. R.
,
Marks
,
M. P.
, and
Pelc
,
N. J.
,
1994
, “
Blood Flow in Major Cerebral Arteries Measured by Phase-Contrast Cine MR
,”
Am. J. Neuroradiol.
,
15
(
1
), pp.
123
129
.
27.
Valdueza
,
J. M.
,
Balzer
,
J. O.
,
Villringer
,
A.
,
Vogl
,
T. J.
,
Kutter
,
R.
, and
Einhaupl
,
K. M.
,
1997
, “
Changes in Blood Flow Velocity and Diameter of the Middle Cerebral Artery During Hyperventilation: Assessment With MR and Transcranial Doppler Sonography
,”
Am. J. Neuroradiol.
,
18
(
10
), pp.
1929
1934
.
28.
Raghavan
,
M. L.
,
Ma
,
B.
, and
Harbaugh
,
R. E.
,
2005
, “
Quantified Aneurysm Shape and Rupture Risk
,”
J. Neurosurg.
,
102
(
2
), pp.
355
362
.
29.
CD-Adapco
,
2013
, “
STAR-CD Methodology
,” Ver. 4.2, CD-Adapco, Melville, NY.
30.
Boussel
,
L.
,
Rayz
,
V.
,
McCulloch
,
C.
,
Martin
,
A.
,
Acevedo-Bolton
,
G.
,
Lawton
,
M.
,
Higashida
,
R.
,
Smith
,
W. S.
,
Young
,
W. L.
, and
Saloner
,
D.
,
2008
, “
Aneurysm Growth Occurs at Region of Low Wall Shear Stress: Patient-Specific Correlation of Hemodynamics and Growth in a Longitudinal Study
,”
Stroke
,
39
(
11
), pp.
2997
3002
.
31.
Chatziprodromou
,
I.
,
Tricoli
,
A.
,
Poulikakos
,
D.
, and
Ventikos
,
Y.
,
2007
, “
Haemodynamics and Wall Remodelling of a Growing Cerebral Aneurysm: A Computational Model
,”
J. Biomech.
,
40
(
2
), pp.
412
426
.
32.
Kim
,
M.
,
Ionita
,
C.
,
Tranquebar
,
R.
,
Hoffmann
,
K. R.
,
Taulbee
,
D. B.
,
Meng
,
H.
, and
Rudin
,
S.
,
2006
, “
Evaluation of an Asymmetric Stent Patch Design for a Patient Specific Intracranial Aneurysm Using Computational Fluid Dynamic (CFD) Calculations in the Computed Tomography (CT) Derived Lumen
,”
Proc. SPIE
,
6143
, p. 61432G.
33.
Jiang
,
J.
, and
Strother
,
C.
,
2009
, “
Computational Fluid Dynamics Simulations of Intracranial Aneurysms at Varying Heart Rates: A ‘Patient-Specific’ Study
,”
ASME J. Biomech. Eng.
,
131
(
9
), p.
091001
.
34.
Pope
,
S. B.
,
2000
,
Turbulent Flows
,
Cambridge University Press
,
Cambidge, UK
.
35.
Xiang
,
J.
,
Tutino
,
V. M.
,
Snyder
,
K. V.
, and
Meng
,
H.
,
2014
, “
CFD: Computational Fluid Dynamics or Confounding Factor Dissemination? The Role of Hemodynamics in Intracranial Aneurysm Rupture Risk Assessment
,”
Am. J. Neuroradiol.
,
35
(
10
), pp.
1849
1857
.
36.
Byrne
,
G.
, and
Cebral
,
J.
,
2013
, “
Vortex Dynamics in Cerebral Aneurysms
,”
arXiv:1309.7875
, epub.
37.
Byrne
,
G.
,
Mut
,
F.
, and
Cebral
,
J.
,
2014
, “
Quantifying the Large-Scale Hemodynamics of Intracranial Aneurysms
,”
Am. J. Neuroradiol.
,
35
(
2
), pp.
333
338
.
38.
Castro
,
M. A.
,
Putman
,
C. M.
,
Sheridan
,
M. J.
, and
Cebral
,
J. R.
,
2009
, “
Hemodynamic Patterns of Anterior Communicating Artery Aneurysms: A Possible Association With Rupture
,”
Am. J. Neuroradiol.
,
30
(
2
), pp.
297
302
.
39.
Cebral
,
J. R.
,
Mut
,
F.
,
Weir
,
J.
, and
Putman
,
C.
,
2011
, “
Quantitative Characterization of the Hemodynamic Environment in Ruptured and Unruptured Brain Aneurysms
,”
Am. J. Neuroradiol.
,
32
(
1
), pp.
145
151
.
40.
Shaaf
,
M.
,
Cagle
,
S. K.
, and
Farris
,
B. K.
,
1994
, “‘
Mickey Mouse’ Aneurysm Presenting With Cranial Bruit: Case Report
,”
Neurosurgery
,
35
(
3
), pp.
509
512
; Discussion 512.
41.
Steiger
,
H. J.
, and
Reulen
,
H. J.
,
1986
, “
Low Frequency Flow Fluctuations in Saccular Aneurysms
,”
Acta Neurochir.
,
83
(
3–4
), pp.
131
137
.
42.
Nerem
,
R. M.
,
Seed
,
W. A.
, and
Wood
,
N. B.
,
1972
, “
An Experimental Study of the Velocity Distribution and Transition to Turbulence in the Aorta
,”
J. Fluid Mech.
,
52
(
1
), pp.
137
160
.
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