Ansari, Sameer A

Batjer, Hunt

Bendok, Bernard R

Carr, James

Carroll, Timothy J

Hurley, Michael

Markl, Michael

Schnell, Susanne

Vakil, Parmede

English

PubMed

Schnell Susanne

Ansari Sameer A

Vakil Parmede

Hurley Michael

Carr James

Batjer Hunt

Bendok Bernard R

Carroll Timothy J

Markl Michael

Directory of Open Access Journals

Journal of Cardiovascular Magnetic Resonance

Characterization of cerebral aneurysms using 4D FLOW MRI

Susanne Schnell

Sameer A Ansari

Parmede Vakil

Michael Hurley

James Carr

Hunt Batjer

Bernard R Bendok

Timothy J Carroll

Michael Markl

Springer - Publisher Connector

WORKSHOP PRESENTATION Open Access
Characterization of cerebral aneurysms using 4D
FLOW MRI
Susanne Schnell1*, Sameer A Ansari2, Parmede Vakil1, Michael Hurley1, James Carr1, Hunt Batjer2,
Bernard R Bendok2, Timothy J Carroll1, Michael Markl1
From 15th Annual SCMR Scientific Sessions
Orlando, FL, USA. 2-5 February 2012
Summary
Six patients with large or giant cerebral aneurysms were
examined with 4D-Flow MRI and analyzed regarding 3D
flow patterns and aneurysm wall shear stress (WSS).
Two distinct groups of aneurysms were identified with
fast swirling flow versus slow flow and significantly dif-
ferent WSS patterns, correlating with aneurysm
morphology.
Background
Cerebral aneurysms are diverse and life threatening con-
ditions. They typically develop at the major bifurcation
sites of the intracranial vessels. In general, increasing
size has been linked to higher rupture risk but specific
data concerning which lesions will grow or de-stabilize
is lacking. In patients with large and giant cerebral
aneurysms, 4D-Flow MRI was employed to characterize
hemodynamics and WSS patterns and their association
with aneurysm location, shape and size.
Methods
Six patients (4 females, 2 males, mean age 56.6 ±14.8)
with large or giant cerebral aneurysms (mean largest
dimension = 2.6 +/-0.9, range = 1.4 - 4.2 mm) were stu-
died. Aneurysms were located near the ICA bifurcation
(n=4) with a saccular/spherical morphology or the basi-
lar artery (n=2) with a fusiform morphology and exam-
ined using 4D flow MRI (3T TRIO & 1.5T Avanto,
Siemens, Germany, spatial resolution = 0.99-1.8 mm x
0.78-1.46 mm x 1.2-1.4 mm, temporal resolution = 5.5-6
ms, 3-directional velocity encoding with venc = 70-80).
Data were analyzed with in-house Matlab-based tools
(Bock et al., Proc ISMRM 2007) and 3D blood flow
visualization software (ENSIGHT, CEI, USA). Intra
aneurysmal flow was visualized using time-resolved
pathlines (Figure 1) and vector graphs mapped onto a
2D plane through the center of the aneurysm (Figure 2).
The WSS pattern along the aneurysm wall was calcu-
lated by cubic spline interpolation of the velocity gradi-
ent along the aneurysm contour as described previously
(Stalder et al., MRM2007).
Results
The combination of 3D spatial encoding and 3-direc-
tional velocity encoding allowed for the 3D visualization
of complex intra-cranial flow patterns (Figure 1). All
aneurysms could be well segmented using the velocity
data combined with magnitude data. As shown in Figure
2, flow patterns in the six aneurysms were classified in
two morphological groups. Narrow high-flow channels
along the aneurysm wall in combination with large cen-
tral low flow regions were identified in saccular/spheri-
cal aneurysms of the anterior circulation (ICA or MCA
group 1, n=4). In contrast, slow flow with less defined
flow channels were noted in fusiform aneurysms (VA or
BA group 2, n=2) (Figure 2, top row). The distribution
of WSS along the aneurysm wall (white lines, Figure 2)
was significantly more heterogeneous and increased for
group 1 compared to group 2 (paired t-test after verifi-
cation of normal distribution, 0.63+/-0.33 vs. 0.038
+/-0.016, Sig(2-tailed)<0.01).
Conclusions
The findings of this feasibility study show the potential
of 4D flow MRI to identified differences in flow charac-
teristics and WSS patterns in two intracranial aneurysm
morphology groups. Future longitudinal studies based
on the measurement, analysis and visualization of cere-
bral aneurysms using 4D-Flow MRI have the potential
1Dept. of Radiology, Northwestern University, Feinberg Medical School,
Chicago, IL, USA
Full list of author information is available at the end of the article
Schnell et al. Journal of Cardiovascular Magnetic Resonance 2012, 14(Suppl 1):W2
http://www.jcmr-online.com/content/14/S1/W2
© 2012 Schnell et al; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons
Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in
any medium, provided the original work is properly cited.
Figure 1 Images A to D show aneurysms of group 1 (fast flow with clear flow channels) with spherical shape located at segment C7 of ICA or
M1 of MCA. Images E and F show the two fusiform aneurysms of group 2 with slow and swirling flow located at the junction of the vertebral
arteries or in the basilar artery. The dashed white boxes indicate the location of the aneurysms.
Figure 2 Box Plot of WSS for 12 equally distributed points along the border of the outlined plane through the aneurysm. The WSS was
averaged over all cardiac cycles. The top row shows the chosen cut-planes through the aneurysms. A paired t-test showed that group 1 and
group 2 have different means, meaning they are drawn from different distributions. The significance was below 0.01 (2-tailed).
Schnell et al. Journal of Cardiovascular Magnetic Resonance 2012, 14(Suppl 1):W2
http://www.jcmr-online.com/content/14/S1/W2
Page 2 of 3
to correlate disease progression with regional hemody-
namics; and may thus, improve risk stratification and
interventional or surgical treatment planning.
Funding
DFG (German Research Foundation) SCHN 1170/2-1.
Author details
1Dept. of Radiology, Northwestern University, Feinberg Medical School,
Chicago, IL, USA. 2Dept. of Neurological Surgery, Northwestern University,
Feinberg Medical School, Chicago, IL, USA.
Published: 1 February 2012
doi:10.1186/1532-429X-14-S1-W2
Cite this article as: Schnell et al.: Characterization of cerebral aneurysms
using 4D FLOW MRI. Journal of Cardiovascular Magnetic Resonance 2012
14(Suppl 1):W2.
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Schnell et al. Journal of Cardiovascular Magnetic Resonance 2012, 14(Suppl 1):W2
http://www.jcmr-online.com/content/14/S1/W2
Page 3 of 3


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Characterization of cerebral aneurysms using 4D FLOW MRI

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