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Recent Innovations in PET and hybrid modality technologies

Recent Innovations in PET and hybrid modality technologies. Bernard Bendriem, Ph.D. Vice President, PET R&D 9 th International SAC Seminar on New trends on PET. Lung cancer: response to therapy (Hanna, Nahmias). Week 7. Week 1. Week 7. Week 1. Responder. Non-responder.

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Recent Innovations in PET and hybrid modality technologies

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  1. Recent Innovations in PET and hybrid modality technologies Bernard Bendriem, Ph.D. Vice President, PET R&D 9th International SAC Seminar on New trends on PET

  2. Lung cancer: response to therapy (Hanna, Nahmias) Week 7 Week 1 Week 7 Week 1 Responder Non-responder Patient alive 20 months after end of chemotherapy Patient survived 2 months after end of chemotherapy Courtesy of David Townsend, Ph.D. University of Tennessee Medical Center

  3. Improving detectability and quantification • Hybrid imaging

  4. Hybrid imaging Morphology Physiology Metabolism Molecules CT US MRI, MRS NM Fluorescence- Optical Dynamic, Perfusion Dynamic, Flow, Perfusion 106 -108 molecules/cell Dynamic, Flow, Perfusion, Diffusion, Molecules 1 molecule/cell Perfusion, Molecules Several molecules/cell Molecules

  5. CT (anatomy) PET (function) • to image different aspects of disease • to identify tracer uptake • to simplify the image interpretation • to give added value to CT and PET Form + function Why combine form and function? Fused image accurately localizes uptake into a lymph node and thus demonstrates spread of disease. PET/CT Courtesy of David Townsend, Ph.D. University of Tennessee Medical Center

  6. I-131 SPECT•CT: Residu thyroidien vs. Metastases ganglionnaires University of Erlangen

  7. Advantages of CT-based correction • standard transmission sources not required • much higher statistical quality (400 MBq vs2·109 MBq) • much faster scan (20 s compared with 20 min) • less patient movement during scan • more tolerable for the patient • shorter total scan duration

  8. Improving detectability and quantification • Hybrid imaging • Organ motion

  9. Whole-body respiratory gated PET/CT: Simulations • Spherical VOI that tracks with motion over 10 respiratory phases Courtesy of Dr. Kinahan University of Washington

  10. Whole-body respiratory gated PET/CT: Patients • Respiratory motion is distributed throughout the whole body • Impact is rarely on detection, but often affects quantitation Static wholebody Single respiratory phase (1 of 7, so noisier) < 1 cc lesion on CT Courtesy of Dr. Kinahan University of Washington

  11. Improving detectability and quantification • Hybrid imaging • Organ motion • Spatial resolution

  12. 2.0 3.9 1.3 3.3 3.7 8.7 4.1 8.6 100 50 0 37 28 22 17 Recovery (%) 13 10 Sphere diameter (mm) The clinical importance of spatial resolution 8 x 8 elements/block6.4 mm x 6.4 mm Low-REZ; 8.6 mCi; 60 min uptake HI-REZ; 11.2 mCi; 90 min uptake 13 x 13 elements/block4.0 mm x 4.0 mm Courtesy of David Townsend, Ph.D. University of Tennessee Medical Center

  13. 2 mm 5 6 6 3 c r y s t a l b l o c k 1 5 8 7 0 Smaller pixels……Research HRRT Detector Block Design • 8X8 crystal matrix • 128 Single crystals per block LYSO (10 mm) LSO (10 mm) Light Guide P M T P M T 1 9 . 5 m m 2 0 3 1 • LYSO only used for pulse shape discrimination c o l u m n s

  14. Ventral striatum VTA & SNr High Resolution Research Tomograph Investigation of small dopaminergic structures playing a crucial rôle in the reward circuit, such as : - Ventral striatum (Accumbens nucleus) - Midbrain (SNr & VTA) • High spatial PET imaging is promising for the exploration of subtle modifications in small and complex brain structures. Courtesy of Pr Syrota Service Hospitalier Frederic Joliot, Orsay

  15. Improving detectability and quantification • Hybrid imaging • Organ motion • Spatial resolution • Number of detected photons

  16. Clinical workflow: reduced imaging times 2 min/bed 30 sec/bed 3 min/bed 2.5 min 10 min 15 min Total scan duration (5 beds) 79 year-old female (103 lbs) referred for restaging of colon cancer. PET/CT identifies uptake in left pelvic mass increasing since previous scan. Also interval development of soft tissue mass in right gluteal region and mild focally increased FDG activity in the region of the ninth thoracic vertebra.Scan acquired at 5 bed positions; 10 mCi, 92 min pi.

  17. How to improve intrinsic sensitivity? • thicker crystals • extended axial FOV B 20 mm to 30 mm A g (511 keV) D C sensitivity increase: 40% 16.2 cm to 21.6 cm sensitivity increase: 77% 3D (no septa)

  18. Advantages of the extended axial field-of-view bed # 5 15 min Standard: 4 8 min Extended FOV: • higher sensitivity = shorter imaging per bed (or more counts) • larger axial FOV = fewer bed positions for same axial coverage

  19. Staging melanoma with extended field-of-view Total scan duration: 22 min CT: 30 mAs, 130 kV, 5 mm slices at 0.75 mm PET: 10 mCi FDG, 108 min pi, 2 min/bed, 11 beds 27 year-old female (123 lbs) with metastatic melanoma. Uptake in left lower extremity and in left axillar node positive for melanoma. Courtesy of David Townsend, Ph.D. University of Tennessee Medical Center

  20. Lung cancer Biograph 15.1 mCi, 90 min pi 4 min/bed, 5 beds 4i / 8s; 5f PET/CT Scan duration: 20 min 60 year-old male (187 lbs) with history of NSCLC commencing a seven week course of chemotherapy. Baseline PET/CT scan shows hypermetabolic left hilar mass consistent with known malignancy. Left anterolateral 4th and 5th rib activity is suspicious for metastases. Courtesy of David Townsend, Ph.D. University of Tennessee Medical Center

  21. Torso phantom study 4.9 mm Brain-torso-bladder phantom scanned with a total of 9 mCi in phantom. Activity in the torso phantom at time of scan is ~3 mCi 7.8 mm 6.2 mm 4.9 mm Imaging time based on equivalent total acquisition time for whole body scan. Sphere diameters: 7.8 mm; 6.2 mm, 4.9 mm Contrast ratio in spheres: 8:1 7.8 mm 6.2 mm

  22. Advantage of extended axial FOV in PET • scanner operational since late February 2006 • scan time reduced by factor ~2 • equivalently the dose can be reduced by factor of 2 • improved image quality for large patients (up to 450 lbs) • HI-REZ detectors resolve smaller details (kidney) • melanoma scan now from head to toe in < 25 min

  23. Improving detectability and quantification • Hybrid imaging • Organ motion • Spatial resolution • Number of detected photons • Image reconstruction

  24. True Counts & Noise Scatter Coincidence Trues Coincidence Random Coincidence

  25. Patient MN. 297 lbs (135 kg) FORE + OSEM, 4i x 8s, 8 mm filter 0 – 21% max window Scatter corrected No scatter correction high residual in left ventricle scatter from liver hot lung walls

  26. Patient MN. 297 lbs (135 kg) Sinogram profiles Measured emission _ _ _ _ Computed scatter 396 MBq injection 157 min uptake 52% Scatter 54% Scatter

  27. Time-of-Flight Acquisition: Principles • Time-of-flight reduce noise propagation during image reconstruction process TOF filter Back projection along the LOR FOV

  28. Time Resolution (ns) Dx (cm) SNR improvement (20 cm object) SNR improvement (40 cm object) 0.1 1.5 3.7 5.2 0.3 4.5 2.1 3.0 0.5 7.5 1.6 2.3 1.2 18.0 1.1 1.5 Time-of-Flight and SNR

  29. TOF shorter scan similar CRC and noise 60s 180s TOF higher CRC similar noise and scan time 60s TOF lower noise similar CRC and scan time 60s Measurements: 27-cm lesion phantom 6-to-1 contrast TOF Non-TOF Courtesy of Joel Karp University of Pennsylvania

  30. Gemini TF - patient study Rectal carcinoma, metastases in mesentery and bilateral iliac chains 114 kg; BMI = 38.1 12 mCi; 2 hr post-inj 3min/bed non-TOF TOF Lesion contrast (SUV) improves with TOF reconstruction Courtesy of Joel Karp University of Pennsylvania

  31. Improving detectability and quantification • Hybrid imaging • Organ motion • Spatial resolution • Number of detected photons • Image reconstruction • Other hybrid imaging

  32. Lésion d’un sésamoïde(premier métatarsien)

  33. New Hybrid imaging : MR-PET Benefits • Isocentric & simultaneous measurements • Perfect anatomical matching • Important for attenuation correction and motion correction • Good soft tissue contrast • Neuro • Abdomen • No additional ionizing radiation through MR • Enables follow up studies • Gating and Motion Correction MR  PET • Prospective and retrospective • Functional MR data adds further information • Spectroscopy, fMRI, CE dynamics (Resolution enhancement due to reduced position range at UHF)

  34. MR Scanner PET Scanner MR Scanner PET Scanner Analogous to PET-CT MR-PET Concepts Integrated System PET-Insert MR PET • No simultaneous measurement, no iso-centric measurement • Reduced MR compatibility demand (only main field) • Upgrade of existing MR scanners possible • Reduced FOV for PET • Integrated development necessary

  35. High resolution artifact free PET images High resolution artifact free MR images 1.5mm 1.0mm 2.0mm 3.5mm 2.5mm 3.0mm Simultaneous dual-modality data acquisition

  36. Improving detectability and quantification • Hybrid imaging • Organ motion • Spatial resolution • Number of detected photons • Image reconstruction • Other hybrid imaging • Advancement in term of higher spatial resolution, higher statistics, larger axial coverage and better image reconstruction, including TOF information and other physical characteristics of instrument. • New relevant hybrid imaging, new imaging protocol with organ motion correction.

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