Vulnerable Plaque: Pathologists View Signal Quantification · Marcelo Andia, KCL and PUC...
Transcript of Vulnerable Plaque: Pathologists View Signal Quantification · Marcelo Andia, KCL and PUC...
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MR Imaging of Atherosclerosis
René M. Botnar, PhD Chair of Cardiovascular Imaging Division of Imaging Sciences and Biomedical Engineering King’s College London
Atherothrombosis
Adapted from Choudhury et al. Nat Rev Drug Discov. 2004
Biomarkers*in*Atherosclerosis*
albumin
Vulnerable Plaque: Pathologists View
A) Pathogenesis of atherosclerosis. Falk E et al. J Am Coll Cardiol 2006; 47:C7-12 B) The popcorn plaques. Jagat Narula & H William Strauss. Nature Medicine 13, 532 - 534 (2007)
A)# B)#
Signal Quantification
Pulse#sequences#can#be##designed#to#allow#
quan3fy*3ssue*T1,*T2*and*T2**relaxa3on*3mes*
T1#and#T2*#mapping#allows*quan3fica3on*of*contrast*agents*based*on*their*T1*and**T2**values*
*
N AQ N AQ N AQ N AQ
S S S
t
Mz
S Saturation pulse N Navigator AQ SSFP acquisition
1/T1 = 1/T10 + r1 * [Gd]
Mz(t) = M0 – M0•exp(-t/T1)
Heart rate independent!
T1 Mapping: Saturation Recovery
raw data
subject #1 #2 #3 #4 mean ± SD
T1pre[ms] 737 737 737 737 n/a
T1post[ms] 366 377 354 316 353 ± 27
c [µMol] 92 86 98 121 99 ± 15
T1 T1w
RV LV
RVOT
1500 ms
60 ms
LAD
60 ms 60 ms
T1 T1 1500 ms 1500 ms T1 maps T1w BB image
Quantification of Contrast Uptake
2
AQ
t
Mz
T1 Mapping: Inversion Recovery
AQ AQ AQ AQ AQ AQ AQ IR IR
M0*
M0
-M0*
1/T1 = 1/T10 + r1 * [Gd]
Estimation of Relaxivity
0"
50"
100"
150"
200"
250"
0.2" 1" 1.8" 2.6" 3.4" 4.2" 5" 5.8" 6.6" 7.4" 8.2" 9" 9.8"
R1#[1
/s]#
contrast#agent#concentra0on#[Gd]#
Relaxa0on#rate#vs.#Gd#concentra0on#
r1"="5/s"
r1"="10/s"
r1"="20/s"
R1 = R10 + r1 * [Gd]
r1 = ΔR1 / [ΔGd]
R1 = R10 + r1 * [Gd] R1 = 1/T1
Marcelo Andia, KCL and PUC
Quantification of Contrast Uptake
RF
Gy
Gx
Signal Signal
RF
Gy
Gx T2*
Cartesian Radial
T2*
T2* Quantification
signal = A*e-n*TE/T2* n = echo number TEn = n-th echo time A = Mz * cos (alpha)
T2* Quantification
signal = A*e-n*TE/T2* n = echo number TEn = n-th echo time A = Mz * cos (alpha)
1T2*
= 1T2
+ 1T2'
1T2'
= 1γ ⋅ ΔB
R2* = R20* + r2* ⋅[Gd]
R2* = 1T2*
A ⋅e−n⋅ TE
T 2*
T2* Quantification
y = 3.1234x - 97.831 R² = 0.96109
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
90.0
100.0
20 30 40 50 60 70 80
% Y
ello
w s
tain
(Red
Cel
ls)
Thrombus Average R2* value [Hz]
y = 7.3238ln(x) + 10.314 R² = 0.94163
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
45.0
0 5 10 15 20 25 30
Ave
rage
T2*
Thr
ombu
s Va
lue
[ms]
Days after Venous Thrombosis
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Tissue Characterization
Pulse#sequences#can#be#designed#to#allow#differen3ate*between*3ssues*based*on*their*T1*and*T2*relaxa3on*3mes*
T1w,#T2w#and#PDw#MRI#allows*enhancing*or**suppressing*3ssues*based**on*their*T1,*T2*or*proton**density*values*
*
Imaging Sciences Interdisciplinary
Medical Imaging Group BLACK BLOOD T1W IMAGING
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ECG
Mid$diastole+
NAV
3D TSE or TFE TE = shortest Fa
tSat
Dua
l-IR
prepulses+ imaging+ECG triggered: TR = every heart beat Non triggered: every TR= 300-500ms
iMSD
E
QIR
Imaging Sciences Interdisciplinary
Medical Imaging Group DUAL-INVERSION T1W IMAGING
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ECG
Mid$diastole+
3D TSE TE = shortest Fa
tSat
prepulses+ imaging+ECG triggered: TR = every heart beat Non triggered: every TR= 300-500ms
RF
180° 180°
Gz
Dual-IR Black Blood Imaging
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ECG
Mid$diastole+
3D TSE TE = shortest Fa
tSat
RF
180° 180°
Gz
Intraplaque Hemorrhage
Mz
1
-1
α α α α α
black blood
180° 180°
Imaging Sciences Interdisciplinary
Medical Imaging Group QUADRUPLE INVERSION
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ECG
Mid$diastole+
3D TSE TE = shortest Fa
tSat
prepulses+ imaging+ECG triggered: TR = every heart beat Non triggered: every TR= 300-500ms
RF
180° 180°
Gz
RF
180° 180°
Gz
TI1 TI2
QIR Black Blood Imaging
Post contrast: fibrous cap enhancement
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ECG
Mid$diastole+
3D TSE TE = shortest Fa
tSat
RF
180° 180°
Gz
180° 180°
Mz
nsIR Acquisition
TI1
nsIR
TI2
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iMSDE Based Black Blood Imaging
Wang J et al. PLoS ONE 6(10): e26567.
Φ(r0, t) = γ ⋅r0 ⋅G ⋅ t
Φ(v, t) = γ ⋅v ⋅G ⋅ t2
Static spins:
Moving spins:
B1(t)
90°
G(t)
Φ(t)
static
moving
S(t)
Comparison– Dual-IR vs. iMSDE
Dual$IR+ iMSDE+
iMSDE+coronary+wall+
1. Wang J et al. PLoS ONE 6(10): e26567.
Imaging Sciences Interdisciplinary
Medical Imaging Group T2W IMAGING
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ECG
Mid$diastole+
NAV
3D TSE TE = 50-80ms Fa
tSat
Dua
l-IR
prepulses+ imaging+ECG triggered: TR = every 2nd heart beat Non triggered: every TR= 2000-3000ms
iMSD
E
QIR
Imaging Sciences Interdisciplinary
Medical Imaging Group PDW IMAGING
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ECG
Mid$diastole+
NAV
3D TSE TE = shortest Fa
tSat
Dua
l-IR
prepulses+ imaging+ECG triggered: TR = every 2nd heart beat Non triggered: every TR= 2000-3000ms
iMSD
E
QIR
T1w, T2w, PDw and TOF Images
iMSDE+
Figure 4
* * *
* *
TOF T1W CE-T1W
PDW T2W
Contrast Enhanced Imaging
Pulse#sequences#can#be#designed#to#visualize#contrast*agents*based*on*their*T1*or*T2*shortening*effects*
#Inversion#recovery#or#DCEFMRI#
allows*enhancing*3ssues*with*gadolinium*uptake*while**suppressing*3ssues**without*contrast*uptake*based*on*their*T1*relaxa3on*3me*values*
*
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Imaging Sciences Interdisciplinary
Medical Imaging Group INVERSION RECOVERY (T1W)
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ECG
Mid$diastole+
NAV
3D TFE Fa
tSat
IR
prepulses+ imaging+
Inversion Recovery Imaging (T1w)
DE-MRI Fusion HE EvG
Control
4 weeks HFD
8 weeks HFD
12 weeks HFD
Treatment
a Inversion delay
ECG Inversion delay
trigger delay
Mz
1
-1
α α α α α
background tissue
180° Gd
blood
DE-MRI
Intraplaque Hemorrhage Imaging
DE-MRI
Kawasaki*T*et*al.*JACC*Imaging.*2009*Oei*ML*et*al.*Eur*Radiol.*2010
CTA CTA MRA
DE-MRI DE-MRI
Imaging Sciences Interdisciplinary
Medical Imaging Group DCE-MRI
B1(t)
Gx(t)
S(t)
α
Gz(t)
Gy(t)
2D GRE 2D GRE
B1(t)
Gx(t)
S(t)
α
Gz(t)
Gy(t)
10-30s
5-10ms
DCE-MRI Images
Figure 8
Lumen/Wall Identification on
T1W image
Registration / Filtering of DCE-MRI
Automated Processing of
DCE-MRI
Registration of Lumen
Boundary
Blood CurveExtraction
Kinetic Modeling
Optimization of Outer Wall Boundary Average
Ktrans
Ct(t): tissue Gd concentration Cp(t): plasma Gd concentration
Non Contrast Angiography
Spin#Labeling#or#T2prep#allows*enhancing*or**suppressing*3ssues*based**on*their*T1,*T2*values*
*
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180x° Non
Selective
Adiabatic Pulse
TI 1 TI 2
RR
Trigger Delay
nsIR sIR AQ NNR NS
180x°
Selective
Rest Slab
180x° Non
Selective
Adiabatic Pulse
180x°
Navigator
Restore
nsIR
�������������Mz
nsIR Acquisition
TI1
nsIR
TI2
180x° Non
Selective
Adiabatic Pulse
TI 1 TI 2
RR
Trigger Delay
nsIR sIR AQ NNR NS
180x°
Selective
Rest Slab
180x° Non
Selective
Adiabatic Pulse
180x°
Navigator
Restore
nsIR
�������� �Mz
nsIR sIR Acquisition
TI1
nsIR
TI2
180x° Non
Selective
Adiabatic Pulse
TI 1 TI 2
RR
Trigger Delay
nsIR sIR AQ NNR NS
180x°
Selective
Rest Slab
180x° Non
Selective
Adiabatic Pulse
180x°
Navigator
Restore
nsIR
Mz
nsIR sIR Acquisition
TI1
nsIR
TI2
Contrast Enhancement
T1 [ms] T2 [ms] f0 [Hz] flow
Blood 1200 250 0 yes
Muscle 850 50 0 no
Fat 250 100 220 no
Contrast Enhancement
! T2 Prepulse
x
y z
90 -90 180 RF 180 180 180
TE
time
1) Brittain JH, et al., Magn Reson Med. 33:689-696 (1995). 2) Botnar RM, et al.: Circulation. 99(24):3139-3148 (1999).
muscle
blood
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T2prep 90 -90 180 RF 180 180 180
TE
time
T2prep OFF T2prep ON
ECG
3D GRE Nav T2prep
TE1
Gp
Gr
DAQ
Gs
RF
dTE
TR
B)
C)
D)
E)
A)
Water/Fat Coronary Imaging
S0 = (W + F) ⋅eiΦ0 S1 = (W − F) ⋅eiΦ ⋅eiΦ0
W = 0.5 ⋅ S0 + S1
F = 0.5 ⋅ S0 − S1In phase Out of phase
Nehrke K. et al. Radiology
Imaging Sciences Interdisciplinary
Medical Imaging Group
Respiratory Motion Correction
End expiration
End inspiration
3D NAV
2D Self-Navigation
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Motion Correction
Henningsson M et al. MRM 2011
a a
a a
i jj jz z e θ⋅ ⋅= ⋅
2a
a
aFOVπθ ⋅Δ=
a a a→ +Δ
1 2 5 7 (a) (b) (c) (d)
(e) (f) (g) (h)
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Henningsson M et al. MRM 2011
2D Self-Navigation
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Coronary Lumen Sequence
Li D et al. Radiology. 1996 Botnar RM et al. Circulation. 1999 Stuber M et al. JACC. 1999
Coronary Wall Sequence
Inversion!
Dual Inversion!
Spin Echo!
Imaging Sciences Interdisciplinary
Medical Imaging Group VESSEL WALL MRI
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3D Spiral
FatS
at
Local+Inversion+(black+blood)+
180° 180°
RF
Gx
Gy
kx
ky
Coronary Vessel Wall Imaging Double Inversion Radial Sequence
3D radial
Katoh M et al. J Magn Reson Imaging. 2006;23(5):757-62.
Courtesy: Marcelo Andia MD MSc and Markus Henningsson MSc
iT2prep Vessel Wall Imaging (T2prep on / off)
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blood Tissue
L1
L2
L3
4f 4g
4h 4i
4j
LCA
RCA
Ao
1 cm
0.00
0.20
0.40
0.60
0.80
1.00
No
rmal
ized
Sig
nal
Inte
nsi
ty
0.00
0.20
0.40
0.60
0.80
1.00
No
rmal
ized
Sig
nal
Inte
nsi
ty
0.00
0.20
0.40
0.60
0.80
1.00
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rmal
ized
Sig
nal
Inte
nsi
ty
L1 L2 L3
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Conclusions*
• MRI provides many contrast weightings that allow imaging
• vessel lumen
• vessel wall (morphology)
• vessel wall vascularity (DCE-MRI)
• vessel wall biology (CE-MRI)
• advanced motion correction " coronary lumen and vessel imaging
Thank You! • King’s College London
• Alkystis Phinikaridou, PhD • Marcus Makowski, MD • Alberto Smith, PhD • Reza Razavi, MD • Phil Blower PhD • Tobias Schaeffter, PhD • Eike Nagel, MD • Marcelo Andia MD MSc • Sarah Peel, MSc • Markus Henningsson, MSc • Ajay Shah, MD • Michael Marber, MD • Alice Warley, PhD • Friederike Cuello, PhD • Andrea Wiethoff, PhD • Boris Bigalke, MD • Andreas Indermuehle, MD • Britta Butzbach, MD • Rafa Torres, PhD • Andreas Protti, PhD • …
• BIDMC, Harvard, Boston – Warren Manning, MD – Dana Peters, PhD – Reza Nezafat, PhD
• TUM München – Christian von Bary, MD – Tareq Ibrahim, MD – Anne Preissel, VMD – Silvia Schachoff, RT – Albert Schoemig, MD – Markus Schwaiger, MD
• Charité, Berlin – Matthias Taupitz, MD
• Lantheus Medical Imaging – Simon Robinson, PhD – Joel Lazewatsky, PhD – David Onthank, PhD – Richard Cesati, PhD