Motion Correction on Dual ECG and Respiratory Gated 3D Cardiac PET/CT Data
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Transcript of Motion Correction on Dual ECG and Respiratory Gated 3D Cardiac PET/CT Data
Motion Correction on Dual ECG and Respiratory Gated 3D Cardiac PET/CT Data
Mohammad Dawood1,3,4, T Kösters2, M Fieseler1,3, F Büther1,4, X Jiang3, KP Schäfers1,4
1European Institute of Molecular Imaging, University of Münster2Institute for Computational and Applied Mathematics, University of Münster
3Institute of Computer Science, University of Münster4University Hospital Münster
M. Dawood EIMI, Münster
Problem: Motion during data acquisition
PET, Minutes
CT, Seconds
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Problem: 1. Attenuation correction
Inspiration Expiration
PET: Respiratory phases
CT: Static
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Problem: 2. Image blur
Extent of motion
Superimposed image
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Motion artifacts lead to errors:
• wrong „staging“ of the tumors (Osman et al 2003, Erdi et al 2004)
• „Uptake Values“ are incorrect (Nakamoto et al 2004)
• small tumors may remain undetected (Papathanassiou et al 2005)
Solution?
Gating + Motion Correction
Clinical relevance
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Method: Amplitude- vs. Time-based gating
P1 Amplitude basedP1 Time based
P2 Amplitude basedP2 Time based
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Solution: Part 2 - Optical flow
Brightness consistency constraint
I(x,y,z,t) = I(x+∂x,y+∂y,z+∂z,t+∂t)
I.V = -It
I = Grey valueV = Flowx,y,z,t = Position
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Solution: Part 2 - Optical flow
Lucas/Kanade: Optical flow is locally consistent
Ix1Vx+Iy1Vy+Iz1Vz = -It1
. . . .
. . . .
. . . .IxnVx+IynVy+IznVz = -Itn
Local consistency
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Horn/Schunck: Optical flow is globally smooth
∫((I.V+It)+(|u|2+|v|2+|w|2))dxdydz
Solution: Part 2 - Optical flow
Brightness consistency Global smoothness
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Lucas/Kanade + Horn/Schunck + Discontinuity Preservation
Solution: Part 2 - Optical flow
Dawood et al, IEEE Trans Med Imaging, August 2008
Local consistency Global smoothness
∫ (ψ1(I.V+It)+αψ2(w,|u|2+|v|2+|w|2)) dxdydz
Discontinuity preservation
Ψ2 (w,s)
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Results: Visual
PET-Data before correction-8 gates
PET-Data after correction-8 gates
Remaining Motion ~ 0.3 mm << 1 Voxel
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+
Dual ecg and respiratory gating and motion correction
Cardiac contraction, 6 gates
Respiratory motion, 6 gates
Combined motion, 36 gates
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After motion correction, 36 gates
Combined motion, 36 gates
Results: Visual
Combined motion, 36 gates, motion corrected
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Data-based motion correction and reconstruction
Data-based approach outperfoms the image-based motion correction
Lamare et al, Phys Med Bio, 2007
Line of Response
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Attenuation correction: PET-derived dynamic CT-based mu-map
Dynamic CT-based mu-maps derived from a static mu-map and motion information from the PET
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Dual ecg and respiratory gating and motion correction
Target Gate Ungated Motion Corrected
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One gate 12,5 mm
Before motion correction 17,2 mm
After motion correction 12,5 mm
Results: Myocardial thickness
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Results: Myocardial thickness
Thank you!