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

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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

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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

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Yi Guo, et al. Direct Estimation of Tracer-Kinetic Parameter Maps from HighlyUnder-sampled Brain DCE-MRI,Magnetic Resonance in Medicine (early view)