Direct model-based reconstruction for high-resolution whole-brain DCE- MRI Yi Guo MHI pitch presentation Viterbi School of Engineering Ming Hsieh Department of Electrical Engineering Magnetic Resonance Engineering Laboratory
Directmodel-basedreconstructionforhigh-resolutionwhole-brainDCE-
MRIYiGuo
MHIpitchpresentation
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
MagneticResonanceImaging(MRI)
• MRIisanoninvasivemedicalimagingtooltoproduce3Dimagesusingmultiplemagneticfields.• DynamicContrastEnhanced(DCE)MRIacquiresaseriesofimagestocapturethedynamicchangesduringacontrastinjection- Essentialtoevaluatebraintumorandotherabnormality
NyquistsamplinginMRIrawdataspace(k-space)
FFT DynamicContrastEnhancedMRI
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
2
TumorevaluationusingDCE-MRI
TKmaps
KtransDynamicimages
• Tumorseverityevaluation:importantpathologicalinformationfromtracker-kinetic(TK)maps(Ktrans,vp,ve etc.).
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
3
LimitedcoverageandresolutionforconventionalDCE-MRI• 5stemporalresolution,Nyquistsampling(usedclinically)
->7slices,0.9x1.3x7.0mm3 inplaneresolution
CartesianNyquist sampling Limited coverageandresolution
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
4
• 5stemporalresolution,30xundersampling->100slices,0.9x0.9x1.9mm3 inplaneresolution
Under-samplingreconstruction
CartesianGolden-angleradialsamplingat30x
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
5
Zero-paddedimages
• Constrainedreconstruction:
CartesianGolden-angleradialsamplingat30x
Reconstructedimages:Whole-braincoverage
22 1 1 2 1 3 1argmin || || || || || || || || [1]u
xx y F Sx Vx TVx x= + + +
Spatialandtemporalsparsifying transform
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
6
Zero-paddedimages
Under-samplingreconstruction
IndirectestimationofTKparametermaps
7
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
Under-sampledkt-spacedata,ku(t)
AnatomicalImages
ContrastAgentConcentration
TKParameters:Ktrans,vp
Reduced dimension!
ForwardmodellingofTKparametermaps
8
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
Under-sampledkt-spacedata,ku(t)
AnatomicalImages
ContrastAgentConcentration
TKParameters:Ktrans,vp
Reduced dimension!
ForwardmodellingofTKparametermaps
9
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
Under-sampledkt-spacedata,ku(t)
AnatomicalImages
ContrastAgentConcentration
TKParameters:Ktrans,vp
Model-baseddirectestimation
10
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
Under-sampledkt-spacedata,ku(t)
AnatomicalImages
ContrastAgentConcentration
TKParameters:Ktrans,vp
trans
If a general function is used:( ) (K , )u p
fk t f v=
22
,
Can sovle PK maps with an optimization problem:( , ) argmin || ( ) ( , ) ||
transp
trans transp u p
K vK v k t f K v=
Anefficientgradient-basedl-BFGSmethodisusedtosolvetheoptimizationproblem
Upto100xinretrospectivestudy
20x60x100x
Fullysampled
Direct
Indirect
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Ktrans maps
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
Whole-brainTKmapsbymodel-baseddirectreconstruction
Ktrans maps
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
12
Yi Guo, et al. Direct Estimation of Tracer-Kinetic Parameter Maps from HighlyUnder-sampled Brain DCE-MRI,Magnetic Resonance in Medicine (early view)
Whole-brainTKmapsbymodel-baseddirectreconstruction
Vp maps
Viterbi School of EngineeringMing Hsieh Department of Electrical Engineering
Magnetic Resonance Engineering Laboratory
13
Yi Guo, et al. Direct Estimation of Tracer-Kinetic Parameter Maps from HighlyUnder-sampled Brain DCE-MRI,Magnetic Resonance in Medicine (early view)