Quantitative MR Imaging of Acute Stroke Risto Kauppinen.
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Transcript of Quantitative MR Imaging of Acute Stroke Risto Kauppinen.
Quantitative MR Imaging of Acute Stroke
Risto Kauppinen
• Unambiguous diagnosis of acute ischemia by MRI (1990)
• Monitoring expansion of ischaemic damage by MRI (1991)
• rtPA introduced as a therapeutic agent (1996)
• Availability of CT scans for stroke A & E (since mid 90s)
• [Shift to 3T MR scanners in Clinical Radiology (since 2005)]
• [Computing power has increased and become cheaper]
Acute Stoke: Advances since 1990
DWI (45 min) T2w (65 min)
MRI: translation to clinic
DWI (45 min) T2w (65 min)
MRI: translation to clinic
Kuharchyck et al. 1991Warach et al. 1992
Griffin JL et al. Cancer Res 63:3195, 2003
Quantitative MRI (qMRI)
Each pixel in an image is represented by a physically
meaningful number
- Relaxation times (T1, T2, T1), ADC, haemodynamics etc.
- Normative values
- Requires acquisition of multiple data points
Griffin JL et al. Cancer Res 63:3195, 2003
qMRI in clinical settings
Griffin JL et al. Cancer Res 63:3195, 2003
qMRI in clinical settings
Griffin JL et al. Cancer Res 63:3195, 2003
Expectations from imaging in clinics
Radiol Clin N Am 49:1-26 (2011)
Goals in acute stroke management
• Rescue the penumbra
by maximising use of available
treatment strategies
• Patient –specific management
• Guide patient triaging
for investigational therapies
DWI ADC image
qMRI: Diffusion MRI in acute ischaemia
-Catastrophic drop in CBF-Energy failure-Depolarisation-Disturbance in water homeostasis
Grohn et al. J Cereb Blood Flow Metab 20: 316, 2000
ADC and Blood FlowIschaemia compromised normal blood flow
Grohn et al. J Cereb Blood Flow Metab 20: 316, 2000
ADC and Blood Flow
ADC/Trace decrease in acuteischaemiais not an ON-OFF event
motivation for qMRI
Ischaemia penumbra normal blood flow
qMRI: pixelwise histogram of ADCs
VOLUME
ADC
Normal
Ischaemic
Ischaemic+compromised
ADC map
qMRI: pixelwise histogram of ADCs
VOLUME
ADC
Normal
Ischaemic
Ischaemic+compromised
ADC map
qMRI: Potentials of (q)ADC
• State of tissue beyond perfusion-diffusion mismatch as assessed by volume (mis)match• Degree of ischaemia in parenchyma• Guide patient selection for reperfusion therapy
qMRI: Potentials of (q)ADC• State of tissue beyond perfusion-diffusion mismatch as assessed by volume (mis)match• Degree of ischaemia in parenchyma• Guide patient selection for reperfusion therapy
• Image pixels are either absolute T1 or T2 relaxation times
• Absolute T1/T2 are much more sensitive to parenchymal alterations than either T1w or T2w images
MR relaxometry
T1 and T2 in acute stroke
24 h afterischaemia
Dav
T1
T2
25 min ofreperfusion
40
60
80
100
120
T1 (m
s)
20
40
60
80 T2 (m
s)
0.5
0.6
0.70.8
0.9D
av ( 10-3 m
m2/s) 0.5
0.6
0.70.8
0.9
Dav ( 10
-3 mm
2/s)
40
50
60
7080
90
T1 (m
s)
45
55
65
75
T2 (m
s)
35 min ofhypoperfusion
45 min of ischaemia
Gröhn O.H.J. et al. MRM 42: 268, 1999
Multiparametric qMRI in acute ischaemia
-6
-4
-2
0
2
4
T2 (m
s)
-0.5-0.4-0.3-0.2-0.1
00.10.2
Dav
(10
-3 m
m2 /
s)
Time post-ischaemia (min) Time post-ischaemia (min)
8020 40 60
***
*
**
*
*
20 40 60 80
****
**
***
Cortex1Cortex2
Putamen
Areas analysed:
Gröhn O et al. JCBFM 18:911 (1998)
Acute ischaemiaTransition toirreversible
Vertebral arteryocclusions
2 days later
remotecontrolledgradualoccluder
Remote controlgraded occlusion
Time of Stroke Onset by MRI
Jokivarsi et al. Stroke 41; 2335-40, 2010
Vertebral arteryocclusions
2 days later
remotecontrolledgradualoccluder
Remote controlgraded occlusion
a) Controllable forebrain ischaemiab) Cortical hypoperfusion (’misery perfusion’)c) Middle cerebral artery (MCA) occlusion
Time of Stroke Onset
Jokivarsi et al. Stroke 41; 2335-40, 2010
Vertebral arteryocclusions
2 days later
remotecontrolledgradualoccluder
Remote controlgraded occlusion
a) Controllable forebrain ischaemiab) Cortical hypoperfusion (’misery perfusion’)c) Middle cerebral artery (MCA) occlusion
Time of Stroke Onset
Jokivarsi et al. Stroke 41; 2335-40, 2010
Vertebral arteryocclusions
2 days later
remotecontrolledgradualoccluder
Remote controlgraded occlusion
a) Controllable forebrain ischaemiab) Cortical hypoperfusion (’misery perfusion’)c) Middle cerebral artery (MCA) occlusion
Time of Stroke Onset
Jokivarsi et al. Stroke 41; 2335-40, 2010
Calibration for humanbrain parenchyma nottrivial
Absolute T2 in Acute Stroke
Siemonsen et al. Stroke 40: 1612, 2009
<3 hours of stroke: qT2
@1.5T
Cut-off 7.5msSensitivity 0.824Accuracy 0.794ROC 0.757(ROC(ADC) 0.635)
T1 in Acute Stroke
Very early increase in T1
in Str by 63±16ms (+6%)
Able to discriminate lesionexpansion and non-damagingcortex, despite similar CBFvalues in early stroke
30min
2.5h
24h
Multi-parametric MRI of Acute Stroke
Jokivarsi et al. MRM under revision
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T2
TP1
TP2
TP3
TP4
TP5
TP6
C‡‡‡‡ ‡ ‡†‡ ‡ †‡‡ ‡ ‡‡ ‡ †
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T1
TP1
TP2
TP3
TP4
TP5
TP6
B‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
RAFF
TP1
TP2
TP3
TP4
TP5
TP6
D‡‡† ‡ †† ‡†† †
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T1
TP1
TP2
TP3
TP4
TP5
TP6
A‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡
S1
S2
C1
C2
C3
Multi-parametric MRI of Acute Stroke
Jokivarsi et al. MRM under revision
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T2
TP1
TP2
TP3
TP4
TP5
TP6
C‡‡‡‡ ‡ ‡†‡ ‡ †‡‡ ‡ ‡‡ ‡ †
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T1
TP1
TP2
TP3
TP4
TP5
TP6
B‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
RAFF
TP1
TP2
TP3
TP4
TP5
TP6
D‡‡† ‡ †† ‡†† †
-10 %
-5 %
0 %
5 %
10 %
15 %
20 %
25 %
30 %
S1 S2 C1 C2 C3
T1
TP1
TP2
TP3
TP4
TP5
TP6
A‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡ ‡‡‡‡‡ ‡
S1
S2
C1
C2
C3
30 min of ischaemia
24 hours of ischaemia
Focus on endogenous metabolites
qMR spectroscopy (qMRS)
‘1H MRS neurochemical profile at 3T’
Wilson et al. Magn Reson Med 65: 1 (2011)
State-of-the-art 1H MRS
NAA
Cr
(lac)
1H MRS Metabolites in Stroke
Van der Toorn et al. MRM 32: 865 (1994)
Cr NAA
Lac
1H MRS in Acute Stroke
Saunders et al. JMRI 7: 1116 (1997)
Reduced NAA: clinical stroke syndrome, more extensive infarction, severe drop in blood flow, presence of lactate
Increased lactate: large infarcts and reduced NAA
Reduced NAA: clinical stroke syndrome, more extensive infarction, severe drop in blood flow, presence of lactate
Increased lactate: large infarcts and reduced NAA
Low NAA and high lactate predicted expansion of DWI lesion
• Potentials to provide clinically important data from a single exam
• Objective assessment of tissue status (early on)
• Potentially guides clinical management of patients
• Aids to maximise use of available therapies
• Allows patient –specific treatment protocols
qMR in acute stroke: Conclusions
• Standard clinical hardware
• Requires expertise and commitment
• Standardised MR protocols
• Regular QA according to appropriate procedures
• Automated on-line data processing
• Computer-assisted decision making tools
qMRI/S in clinical setting
Stroke Management in the 21st Century
1. Active prevention2. Thrombolysis3. Minocyclin4. Hematopoetic growth factors5. Hypothermia6. Remote preconditioning
• Application specific scanners– Lower capital costs– Lower running costs– Increased availability at A&E– Faster through-put– Improved data quality
• Tissue status assignment for therapeutic procedures• Improving overall outcome of stroke patients
MR in Evaluation of Acute Stroke Patients in 2020s