PMC5040129_01
Computational domains and segmentation of aneurysms in Case 1 (a), Case 2 (b), and Case 3 (c). Aneurysms with atherosclerotic changes are colored yellow (AN2, AN5, and AN8) and others without atherosclerotic changes blue.
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fig1
A 61-year-old male presented with 2 unruptured aneurysms in the right anterior circulation (Table 1, Figures 1 and 4): one at the bifurcation of the left ICA and anterior choroidal artery (AN7) and one at the bifurcation of the MCA (AN8).
Images of rotational angiography and intraoperative photographs showing the locations and appearances of aneurysms in Case 1. Atherosclerotic changes were observed in AN2.
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fig2
Four were on the left side of the anterior circulation (Figures 1 and 2): one at the bifurcation of the left internal carotid artery (ICA) and anterior choroidal artery (AN1), 2 adjacent ones in the horizontal part of the left middle cerebral artery (MCA) (AN2 and AN3), and one at the bifurcation of the left MCA (AN4). At surgery, the left M1 aneurysm (AN2) had thick wall with yellow lipid deposition over the dome, whereas the other 3 aneurysms (AN1, AN3, and AN4) had a reddish dome with a white patch (Figure 2).
PMC5040129_02
Computational domains and segmentation of aneurysms in Case 1 (a), Case 2 (b), and Case 3 (c). Aneurysms with atherosclerotic changes are colored yellow (AN2, AN5, and AN8) and others without atherosclerotic changes blue.
CMMM2016-2386031.001.jpg
PMC5040129_03_CMMM2016-2386031.001.jpg
fig1
A 61-year-old male presented with 2 unruptured aneurysms in the right anterior circulation (Table 1, Figures 1 and 4): one at the bifurcation of the left ICA and anterior choroidal artery (AN7) and one at the bifurcation of the MCA (AN8).
Images of rotational angiography and intraoperative photographs showing the locations and appearances of aneurysms in Case 2. Atherosclerotic changes were observed in AN5.
CMMM2016-2386031.003.jpg
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fig3
In visual inspection of the intraoperative video recording and the contour maps of RRT, the atherosclerotic changes in AN5 and AN8 coincided with the area with long RRT (Figures 3, 7(a), 4, and 8(a), resp.).
PMC5040129_03
Computational domains and segmentation of aneurysms in Case 1 (a), Case 2 (b), and Case 3 (c). Aneurysms with atherosclerotic changes are colored yellow (AN2, AN5, and AN8) and others without atherosclerotic changes blue.
CMMM2016-2386031.001.jpg
PMC5040129_03_CMMM2016-2386031.001.jpg
fig1
A 61-year-old male presented with 2 unruptured aneurysms in the right anterior circulation (Table 1, Figures 1 and 4): one at the bifurcation of the left ICA and anterior choroidal artery (AN7) and one at the bifurcation of the MCA (AN8).
Images of rotational angiography and intraoperative photographs showing the locations and appearances of aneurysms in Case 2. Atherosclerotic changes were observed in AN5.
CMMM2016-2386031.003.jpg
PMC5040129_03_CMMM2016-2386031.003.jpg
fig3
In visual inspection of the intraoperative video recording and the contour maps of RRT, the atherosclerotic changes in AN5 and AN8 coincided with the area with long RRT (Figures 3, 7(a), 4, and 8(a), resp.).
Images of rotational angiography and intraoperative photographs showing the locations and appearances of aneurysms in Case 3. Atherosclerotic changes were observed in AN8.
CMMM2016-2386031.004.jpg
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fig4
A 61-year-old male presented with 2 unruptured aneurysms in the right anterior circulation (Table 1, Figures 1 and 4): one at the bifurcation of the left ICA and anterior choroidal artery (AN7) and one at the bifurcation of the MCA (AN8). ICA-anterior choroidal artery aneurysm had a reddish dome without atherosclerotic changes (Figure 4). In this case, we could perform neck clipping for both aneurysms.
Contour maps of RRT ((a) and (d)), time-averaged WSS ((b) and (e)), and OSI ((c) and (f)) in Case 1. The aneurysm with atherosclerotic changes (AN2) presented with long RRT and low WSS. Black arrows indicated the point with the longest RRT (117.3 (1/Pa)), the lowest WSS (0.02 (Pa)), and the highest OSI (0.36) in AN2. See also Table 2. RRT: relative residence time, WSS: wall shear stress, and OSI: oscillatory shear index.
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fig5
In the contour maps of these 3 parameters, AN2 presented with long RRT and low WSS (Figures 5(a)-5(f)). In AN2, the distribution of the age of blood was similar to the distribution of RRT (Figures 5(a) and 6(f)).
((a)-(e)) Graphs showing the results of computational hemodynamic analysis in Case 1. The graph of the atherosclerotic aneurysm (AN2) is colored yellow. (a) Pulsatile flow rates of the internal carotid artery measured by phase-contrast MR (volume, 271.7 (mL/min); heart rate, 63 (bpm); heart beat duration (T), 0.952 (s)). (b) Volume of inflow. (c) Mean flow velocity inside aneurysms. (d) The spatially averaged value of blood age inside the aneurysms. (e) The maximum values of blood age inside the aneurysms. Note that the maximum age inside AN2 increased linearly, and the inclination was unity over 5 cardiac cycles. (f) Contour maps of blood age (t = 5T). (g) A cutting plane of blood age in AN2 (t = 5T). (h) Velocity vectors on the cutting plane (t = 5T). Old blood was seen near the wall (a black arrow in (g)) due to recirculatory flow (arrowheads in (h)). MR: magnetic resonance.
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fig6
Blood flow entered aneurysms periodically (Figures 6(a)-6(c)). The volume of inflow in AN2 was larger than that in AN1 and smaller than that in AN3 and AN4 (Table 3 and Figure 6(b)). In addition, the mean flow velocity inside AN2 was smaller than in the other 3 aneurysms including AN1 (Figure 6(c)). The mean and maximum age of blood inside each aneurysm changed periodically and were opposite in phase with the inlet flow rates, the inflow volume, and the pulsatile changes of mean flow velocity (Figures 6(a)-6(e)). The maximum age of blood inside 3 aneurysms with reddish walls (AN1, AN3, and AN4) changed periodically with the mean age of blood (Figures 6(d) and 6(e)). On the other hand, the maximum age inside AN2 increased linearly, and the inclination was unity (Figure 6(e)), which means that there is a region with extremely slow recirculation. In the cutting plane, the old blood coincided with recirculatory flow with slow velocity (Figures 6(g) and 6(h)).
Contour maps of RRT (a), time-averaged WSS (b), and OSI (c) in Case 2. The aneurysm with atherosclerotic changes (AN5) presented with long RRT and low WSS. Black arrows indicate the point with the longest RRT (11.6 (1/Pa)), the lowest WSS (0.2 (Pa)), and the highest OSI (0.32) in AN5. See also Table 2. RRT: relative residence time, WSS: wall shear stress, and OSI: oscillatory shear index.
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fig7
In the contour maps of these 3 parameters, two atherosclerotic aneurysms (AN5 and AN8) presented with long RRT and low WSS (Figures 7(a)-7(c) and 8(a)-8(f)). In visual inspection of the intraoperative video recording and the contour maps of RRT, the atherosclerotic changes in AN5 and AN8 coincided with the area with long RRT (Figures 3, 7(a), 4, and 8(a), resp.). In AN5, the distribution of the age of blood was similar to the distribution of RRT (Figures 7(a) and 9(e)).
Contour maps of RRT ((a) and (d)), time-averaged WSS ((b) and (e)), and OSI ((c) and (f)) in Case 3. The graph of the atherosclerotic aneurysm (AN8) is colored yellow. The aneurysm with atherosclerotic changes (AN8) presented with long RRT and low WSS. Black arrows indicate the point with the longest RRT (5.3 (1/Pa)), the lowest WSS (0.2 (Pa)), and the highest OSI (0.29) in AN8. See also Table 2. RRT: relative residence time, WSS: wall shear stress, and OSI: oscillatory shear index.
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fig8
In AN8, the distribution of the age of blood was similar to the distribution of RRT (Figures 8(a) and 10(e)).
((a)-(d)) Graphs showing the results of computational hemodynamic analysis in Case 2. The graph of the atherosclerotic aneurysm (AN5) is colored yellow. (a) Pulsatile flow rates of the internal carotid artery (volume, 305.2 (mL/min); heart rate, 67 (bpm); heart beat duration (T), 0.896 (s)). (b) Volume of inflow. (c) Mean flow velocity inside aneurysms. (d) The spatially averaged value and the maximum value of blood age over 5 cardiac cycles. ((e) and (f)) A surface (e) and a cutting plane (f) of the contour of blood age in AN5 at the time point shown in (d) (a black arrow). Streamlines are also shown in (f) to demonstrate vortex flow inside the aneurysm. Note that old blood was seen at the center of the vortex. WSS: wall shear stress.
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fig9
Blood flow entered aneurysms periodically (Figures 9(a)-9(c) and 10(a)-10(c)). The inflow volumes of atherosclerotic aneurysms (AN5 and AN8) were almost equal to the other nonatherosclerotic ones (AN6 and AN7) (Table 3, Figures 9(b) and 10(b)). However, the mean flow velocity and the exchange rate were smaller in the atherosclerotic aneurysms than in the other nonatherosclerotic aneurysms (Figures 9(c) and 10(c) and Table 3). The mean age of blood inside each aneurysm was opposite in phase with the inlet flow rates, the inflow volume, and the mean flow velocity (Figures 9(d) and 10(d)). In the cutting plane, the old blood was seen in the center of vortex inside AN5 (Figure 9(f)).
((a)-(d)) Graphs showing the results of computational hemodynamic analysis in Case 3. (a) Pulsatile flow rates of the internal carotid artery (volume, 252.7 (mL/min); heart rate, 60 (bpm); heart beat duration (T), 1.000 (s)). (b) Volume of inflow. (c) Mean velocity inside aneurysms. (d) The spatially averaged value and the maximum value of blood age over 5 cardiac cycles. ((e) and (f)) A contour map of blood age (e) and streamlines (f) in AN8 at the time point shown in (d) (a black arrow). Note that old blood was seen around the center of the vortex indicated by streamlines (a black arrow in (f)). WSS: wall shear stress.
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fig10
The old blood was seen around the unstable vortex inside the aneurysm (Figure 10(f)).