2. Coincidence to Image: PET Imaging Jennifer White Marketing Manager SNS Workshop October 13, 2003

3. 2 Coincidence to Image: PET Imaging The PET Mission “Disease is a biological process and PET is a biological imaging technique that uses molecular probes.” -Michael Phelps The CPS mission is to utilize CPS’ unique foundation of knowledge and experience in molecular imaging technology to manage disease better through earlier detection and more complete diagnosis.

4. 3 Coincidence to Image: PET Imaging The Image Fused PET CT Image Brain Imaging Cardiac Image PET CT and PET Dedicated PET

5. 4 Coincidence to Image: PET Imaging PET Principles 18 O (p,n) 18 F 18-F-FDG most common nuclide Other PET Radionuclides 11 C 13 N 15 O 82 Rb

6. 5 Coincidence to Image: PET Imaging Annihilation Reaction e+e+ e-e- Positron emission Positron scatters in tissue losing energy Annihilation 511 keV  - ray

7. 6 Coincidence to Image: PET Imaging PET Principles Detector Block LSO PROCESSING ELECTRONICS

8. 7 Coincidence to Image: PET Imaging PET Principles Acquisition Disk Real Time CPU Ethernet Optical data link Workstation Detector Electronics Gantry Controller Serial line Ethernet Acquisition Memory VSB bus Coincidence Processor Gantry Detectors Singles Events Formatter & Motion Translator Sorter Rotating Rod Converter VME bus ECAT System Schematic

9. 8 Coincidence to Image: PET Imaging PET Principles Line of Response is Defined by connecting Pairs in Coincidence Event Types of Events Detected Prompt True Random Scatter

10. 9 Coincidence to Image: PET Imaging Event Detection

11. 10 Coincidence to Image: PET Imaging Event Detection Collection of Events t = 12ns Delay Constant Fraction Discrim Detector t>>12ns AND Constant Fraction Discrim

12. 11 Coincidence to Image: PET Imaging Sinogram Formation A sinogram is formed by placing the projection for the angle 0 at the top of a matrix and the other angles in ascending order. EXACT, ART, Accel: 192 x 192 elements. HR+: 288 x 288 elements Data is collected as the integral of the activity along parallel rays for each angle from 0 to 180 degrees.

13. 12 Coincidence to Image: PET Imaging PET Principles PROMPT EMISSION SINOGRAM TRUE EMISSION SINOGRAM IMAGE Random Subtraction acquisition time and decay correction calibration/branching fraction correction deadtime correction detector efficiency normalization scatter subtraction ring geometry rebinning attenuation correction

14. 13 Coincidence to Image: PET Imaging Attenuation Corrections – Correction made for number of detection lost Scatter (Compton or Rayleigh interactions) Absorption (photoelectric interaction) – Significance of Attenuation The reconstruction algorithms are not valid without AC. The emitter distribution is distorted. Quantification is not possible. Scattered A B Absorbed Unattenuated Absorbed

15. 14 Coincidence to Image: PET Imaging PET Principles Uncorrected Corrected Image Quality Considerations

16. 15 Coincidence to Image: PET Imaging PET Attenuation Correction Methods of Attenuation Correction: ROD SOURCE Measure rod intensity with no object present. Measure transmission through the object. Smooth and take the ratio. Blank/Transmission = ACF Blank scan Transmission scan Emission scan Measure emission from object. Correct the emission data. E true = E meas x ACF 1 hour2–4 min 4–8 min

17. 16 Coincidence to Image: PET Imaging PET Attenuation Correction Methods of Attenuation Correction: CT soft tissue bone 511 keV ~70 keV

18. 17 Coincidence to Image: PET Imaging Corrected Sinogram to Image measured N = 1 N = 3 FBP OSEM Sinogram

19. 18 Coincidence to Image: PET Imaging PET Images MI projectionPlane 66 FBP OS-EM 7.1 OS-EM 7.2 (prototype) Plane 71 Plane 76 Reconstruction Methods vs Image Quality

20. 19 Coincidence to Image: PET Imaging Putting it all together Transmission scan Emission scan Blank scan Normalization Attenuation correction  -map Image

21. 20 Coincidence to Image: PET Imaging PET Image Reconstruction: multiple bed positions 25 yr old male, melanoma, 71 kg, 178 cm, 16.9 mCiFDG Data courtesy of NCPIC, Sacramento, CA

22. 21 Coincidence to Image: PET Imaging Case Study

23. 22 Coincidence to Image: PET Imaging PET Analysis Measured Activity Weight Volume Injected Activity SUV =  Partial volume effect (Resolution dependent) Size of ROI Size of lesion Resolution Scanner Reconstruction parameter Filter/ Noise Glucose concentration before injection Metabolism Pathologic Stress Time after injection Uptake time Scan length (to reach ROI) Scanner calibration Weight only used as substitute for blood/ water volume! Measuring error (esp. when patient estimate) Tissue/ fat/ bone composition/ distribution Measuring error Cross-calibration

24. 23 Coincidence to Image: PET Imaging Analysis Packages Selected Models Patlak, Logan plots Time-weighted integral method Simplified reference model Ichise’s reference models Logan’s non-invasive model Glucose autoradiography Fractal analysis Fourier analysis PMOD Technologies www.pmod.com

25. 24 Coincidence to Image: PET Imaging Case Study Multi-Planar Fused Sagittal, Coronal, Transaxial Coronal Series

26. 25 Coincidence to Image: PET Imaging Case Study Sub-cm nodes detected with PET localized with CT Patient with history of Breast Cancer evaluated for treatment follow-up. Small 7 mm nodes detected by examination on PET/CT

27. 26 Coincidence to Image: PET Imaging Thank you