Transcript 3D visualization of intra-cardiac flow using MRI data

What is 3D ?
3D velocity
measurement
3D volume of
interest
v
V
u
w
3D + Time  4D
3D Doppler Ultrasound
3D region, but only one velocity component
MRI @ 1,5T
Tesla1.gif
2D MRI Phase Contrast
Vector display of MRI phase contrast data
Early diastole
Systole
3D Cine Phase Contrast
3D Velocity
dataset
v
V
u
w
2D Slices
Wigström et al, Magn Reson Med, 1996;36(5)
Visualization of 3D Velocity Data
Color
coding
Vector
plot
Particle Trace Visualization
Integration of the velocity
field starting in a user
specified timeframe and
at a specified location
LVOT
v2Dt
v1Dt
v3Dt
v4Dt
Apex
LA
v5Dt
v6Dt
Wigström et al, Magn Reson Med, 1999;41(4)
Particle Trace Visualization
LV Diastolic Filling
LVOT
LVOT
LA
LV
Early filling (E)
LA
LV
Late filling (A)
Fyrenius, et al, J Am Soc Echocardiogr, 1999,12:817-21
LV Diastolic Flow Patterns
Vortices behind the mitral leaflets
LVOT
LA
Doppler
LV
MRI
Vortical flow in the left atrium
Right PV
Level of
mitral valve
Level of
mitral valve
Left PV
A. Fyrenius
Automatisk virvelkvantifiering
Hur ser en virvel ut?
Automatisk virvelkvantifiering
Hur ser en virvel ut?
• Begränsad geometri
• “spiralflöde” etc
Att hitta virvel kärnor
• Utgå från ett önskat “mönster”
• Leta igenom hela volymen efter
matchande områden
Exempel
Exempel
Andra flödesstrukturer
• Parallell-flöde
• “Skruv-flöde”
Exempel: Aorta
Pressure differences
Simplified Bernoulli:
Only for stenotic flow at peak inflow
Navier-Stokes:
More general, but time-resolved 3D
velocity field needed
Aortic Pressure Differences
Maximum velocity [m/s]
2
1.5
1
Level of
coarctation
repair
0.5
0
-0.6
-0.4
-0.2
0
Time [s]
0.2
0.4
0.6
0.4
0.6
Pressure difference [mmHg]
0
-5
Normal
-10
Repaired coarctation
-15
-0.6
-0.4
-0.2
0
Time [s]
0.2
Relative Pressure Field
Early Diastole
Beginning
Left
Atrium
Left Ventricular
Outflow Tract
Left
Ventricle
Peak
End
Late Diastole
Left
Atrium
Left
Ventricular
Outflow
Tract
Left
Ventricle
Apex
Myocardial Velocity
Early diastole
LA
Short axis
LV
Long axis
Myocardial Velocities in 3D
Different directions across
the wall in early diastole
Myocardial Velocities in 3D
Radial
Circumferential
Velocity [cm/s]
Longitudinal
Base
Mid
Apex
Kvitting, et. al., ESMRMB 2000
Analysis of 3D Velocity Data
Translation
=
Rotation
+
Strain
+
Passive motion
• Strain
• Strain rate
• Stress - strain relationship ?
Shear-Strain
+
Strain
Strain Rate
1D:
D  dx
2D:
 dx
D
d yx
d xy 

dy 
 dx

D  d yx
 d zx

d xy
3D:
dy
d zy
d xz 

d yz 
d z 
Strain rate (maximum eigenvalue)
Strain rate [1/s]
E
S
A
[s]
Longitudinal expansion
Radial expansion
P. Selskog
Ultraljud är basundersökning för
hjärtanatomi
Ultraljud kan färgkodas för flöde
Vad kan 3D ultraljud tillföra?
•Volymsberäkningar
Volymsberäkning m 3D ultraljud
Vad kan 3D ultraljud tillföra?
•Anatomiska relationer
Volume-rendered hjärteko
Mitralisklaff ur olika vinklar
Mitralisklaff från sidan
Flöde m ultraljud