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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 Dawood 1,3,4 , T Kösters 2 , M Fieseler 1,3 , F Büther 1,4 , X Jiang 3 , KP Schäfers 1,4 1 European Institute of Molecular Imaging, University of Münster

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Motion Correction on Dual ECG and Respiratory Gated 3D Cardiac PET/CT Data

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  1. 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 Münster 2Institute for Computational and Applied Mathematics, University of Münster 3Institute of Computer Science, University of Münster 4University Hospital Münster

  2. Problem: Motion during data acquisition PET, Minutes CT, Seconds

  3. Problem:1. Attenuation correction CT: Static PET: Respiratory phases Expiration Inspiration

  4. Problem: 2. Image blur Extent of motion Superimposed image

  5. Clinical relevance • 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

  6. Method: Amplitude- vs. Time-based gating P1 Amplitude based P1 Time based P2 Amplitude based P2 Time based

  7. 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 value V = Flow x,y,z,t = Position

  8. Local consistency Solution: Part 2 - Optical flow Lucas/Kanade: Optical flow is locally consistent Ix1Vx+Iy1Vy+Iz1Vz = -It1 . . . . . . . . . . . . IxnVx+IynVy+IznVz = -Itn

  9. Global smoothness Brightness consistency Solution: Part 2 - Optical flow Horn/Schunck: Optical flow is globally smooth ∫((I.V+It)+(|u|2+|v|2+|w|2))dxdydz

  10. Local consistency Global smoothness Ψ2 (w,s) Discontinuity preservation Solution: Part 2 - Optical flow Lucas/Kanade + Horn/Schunck + Discontinuity Preservation ∫ (ψ1(I.V+It)+αψ2(w,|u|2+|v|2+|w|2)) dxdydz Dawood et al, IEEE Trans Med Imaging, August 2008

  11. Results: Visual PET-Data before correction -8 gates Remaining Motion ~ 0.3 mm << 1 Voxel PET-Data after correction -8 gates

  12. Respiratory motion, 6 gates Combined motion, 36 gates Cardiac contraction, 6 gates Dual ecg and respiratory gating and motion correction +

  13. Combined motion, 36 gates After motion correction, 36 gates Results: Visual Combined motion, 36 gates, motion corrected

  14. Data-based motion correction and reconstruction Data-based approach outperfoms the image-based motion correction Line of Response Lamare et al, Phys Med Bio, 2007

  15. 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

  16. Target Gate Ungated Motion Corrected Dual ecg and respiratory gating and motion correction

  17. Results: Myocardial thickness One gate 12,5 mm Before motion correction 17,2 mm After motion correction 12,5 mm

  18. Results: Myocardial thickness

  19. Thank you!

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