1. Ultrasound, Positron Emission Tomography, and Single Photon Emission Tomography Allen T. Newton, Ph.D. PAVE 2014

2. PET in cancer imaging Images generated using very similar computations as in CT Spatial resolution: humans and animals ~2 mm Some radioactive isotopes ( 18 F, 15 O, etc) emit positrons: Such elements can be incorporated into metabolically relevant compounds Emitted positron encounters electron, they annihilate leaving 2 photons traveling in opposite directions which are measured by ring of detectors Most common PET tracer is FDG (flourodeoxyglucose), a glucose analog 18 FDG (blood) 18 FDG (tissue) 18 FDG-6-PO 4 (cells) X

5. Positron Emission Tomography J Nucl Med Technol 2002; 30:3949 http://www.cerebromente.org.br/n01/pet/pet_hist.htm

6. Types of Coincidence  True coincidence is the simultaneous detection of the two emissions resulting from a single decay event.  Scatter coincidence is when one or both photons from a single event are scattered and both are detected.  Random coincidence is the simultaneous detection of emission from more than one decay event. Coincidences: TrueScatter Random

7. Positron Emission Tomography Common Tracers

8. Positron Emission Tomography Common Tracers Half life = 110min Half life = 20min

9. PET/CT CT PET CT+PET General Electric Medical Systems

10. PET image reconstruction Projection Object P(  2,r) Radon Transform 11 22 P(  1,r) f(x,y) r r

11. PET image reconstruction Sinogram r  Projection angle Projection bin Object

12. PET image reconstruction Sinogram Object r 

13. PET image reconstruction Sinogram Object r 

14. PET image reconstruction Sinogram Object r 

15. PET image reconstruction Sinogram Object r 

16. PET image reconstruction r  Sinogram Object

17. Sinogram Other representations can be used instead of the sinogram (linogram, planogram) SPECT: 360º (1 photon) PET: 180º (2 opposite photons)

18. PET image reconstruction 2D Reconstruction – Each parallel slice is reconstructed independently (a 2D sinogram originates a 2D slice) – Slices are stacked to form a 3D volume f(x,y,z) 2D reconstruction Plane 5 Slice 5 etc 2D reconstruction Plane 4 Slice 4 2D reconstruction Plane 3 Slice 3 2D reconstruction Plane 2 Slice 2 2D reconstruction Plane 1 Slice 1 2D Reconstruction

19. PET image reconstruction Projection and Backprojection ProjectionBackprojection 2D Reconstruction

20. 4 projections16 projections128 projections Backprojection Filtered Backprojection PET image reconstruction

21. 50 000 counts100 000 counts200 000 counts 500 000 counts1 million counts2 million counts 4.8mm 6.4mm 11.1mm 12.7 mm The Importance of counts 7.9 mm 9.5mm

22. Noise In PET Images Noise in PET images is dominated by the counting statistics of the coincidence events detected. Noise can be reduced at the cost of image resolution by using an apodizing window on ramp filter in image reconstruction (FBP algorithm). 10 5 10 6 10 7 counts Unapodized ramp filter Hanning window, 4mm Hanning window, 8mm

23. Scattered coincidences component Attenuation Random coincidences component Detector efficiency effects True coincidences component PET image reconstruction Data corrections are necessary – the measured projections are not the same as the projections assumed during image reconstruction Object (uniform cylinder) projection measured projection assumed integral of the activity along the line or tube of response

24. PET Image reconstruction Iterative methods Current estimate Measured projection Compare (e.g. – or / ) Error projection projection Estimated projection image space projection space backprojection Error image Update Iteration 1

25. PET Image reconstruction Iterative methods Current estimate Measured projection Compare (e.g. - or / ) Error projection projection Estimated projection image space projection space backprojection Error image Update Estimated projection Iteration 2

26. PET Image reconstruction Iterative methods Current estimate Measured projection Compare (e.g. - or / ) Error projection projection image space projection space backprojection Error image Update Estimated projection Iteration N

27. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

28. Figure 2a. Primary carcinoid nodule of the left upper lung. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

29. Figure 2b. Primary carcinoid nodule of the left upper lung. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

30. Figure 5a. Large cell lung cancer in a 71-year-old woman. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

31. Figure 5b. Large cell lung cancer in a 71-year-old woman. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

32. Figure 15c. Hodgkin disease involving the mediastinal and right cervical lymph nodes. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

33. Figure 15e. Hodgkin disease involving the mediastinal and right cervical lymph nodes. Kostakoglu L et al. Radiographics 2003;23:315-340 ©2003 by Radiological Society of North America

34. Single Photon Emission Tomography

35. Gamma Cameras

36. Single Photon Emission Tomography CT scanner

37. Single Photon Emission Tomography

38. http://cdcfd.wordpress.com/ http://quarknet.fnal.gov/

39. Single Photon Emission Tomography http://cdcfd.wordpress.com/ http://quarknet.fnal.gov/ Each coated with a secondary emissive material (like a scintilation crystal)

40. Single Photon Emission Tomography

41. Again, its all about what molecule you attach the radioactive element to… Note, these all make use of 99 Tc (half life = 6hrs)

42. Reconstruction of a slice from projections example = myocardial perfusion, left ventricle, long axis courtesy of Dr. K. Kouris

43. Single Photon Emission Tomography J Nucl Med May 2007 vol. 48 no. 5 696-703

44. Single Photon Emission Tomography 131I-iodide (half life = 13hrs) scan in a 16 year old patient with thyroid cancer discloses an iodine-avid focus (arrow). The patient had had three surgical procedures (including total thyroidectomy) and 37 GBq of 131I, so that this focus indicates the presence of a further lymph node metastasis. Considering scarring from prior surgeries, exact localization of this lesion is an essential requisite for its surgical resection Clinical Applications of SPECT/CT: New Hybrid Nuclear Medicine Imaging System, IAEA-TECDOC-1597

45. Single Photon Emission Tomography Uptake of 99mTc-MDP is due to arthrosis of the facet joint.

46. Single Photon Tomography “In a recent study comparing the diagnostic accuracy of 99mTc-phosphonate skeletal scintigraphy to that of [18F]FDG-PET in patients with thyroid carcinoma [64], sensitivity of the conventional procedure was not significantly different from that of [18F]FDG-PET. However, its specificity was significantly worse.” “…there are several highly prevalent benign conditions leading to focally increased uptake of the radiolabelled phosphonates in the skeleton. Most of these conditions reflect degenerative processes of the joints increasing in frequency with age, such as spondylarthrosis or coxarthrosis. Additional benign causes of enhanced uptake are rheumatic disease or benign bone tumours. Since most of these benign conditions are readily identifiable on CT, SPECT/CT is expected to improve specificity of skeletal scintigraphy without reducing its sensitivity. Besides single case reports illustrating this assumption, several prospective studies have investigated this issue.”

47. Ultrasound System Transducers Facts: 1-20MHz Tomographic view Mechanical vibrations, no ionizing radiation

48. Ultrasound Aldrich JE, Basic physics of ultrasound imaging, Crit Care Med 2007 Vol. 35, No. 5 (Suppl.) The Anatomy of a Transducer

49. Ultrasound

50. Aldrich JE, Basic physics of ultrasound imaging, Crit Care Med 2007 Vol. 35, No. 5 (Suppl.)

51. Ultrasound Aldrich JE, Basic physics of ultrasound imaging, Crit Care Med 2007 Vol. 35, No. 5 (Suppl.) http://www.bercli.net/

52. Ultrasound High frequency Less penetration Greater resolution Frequency vs Resolution Low frequency Greater penetration Less resolution

53. Ultrasound

63. www.4dfirstimpressions.com

64. www.oakparkultrasound.com

65. www.firstglimpseultrasound.com