Nuclear Medicine Imaging (SPECT and PET) TechniquesNuclear Medicine Imaging (SPECT and PET) Techniques
and Applicationsand...
2/48
Outline of This LectureOutline of This Lecture
Radioactivity
Types of decay
Gamma radiation, source of signals for Nu...
3/48
Four Forces (Interactions) and Their MediatorsFour Forces (Interactions) and Their Mediators
Okay. Then, electromagne...
4/48
Radioactive DecaysRadioactive Decays
Spontaneous Fission
Little importance in nuclear medicine
Alpha (α) Decay
Little...
5/48
BetaBeta++ (Positron) Emission(Positron) Emission
These mostly proton-rich (except 124I) radionuclides are used in po...
6/48
Gamma EmissionGamma Emission -- Isomeric Transition (IT)Isomeric Transition (IT)
Isomer: Nucleus with different arran...
7/48
AlternativeAlternative -- Internal Conversion (IC)Internal Conversion (IC)
Internal Conversion (IC): Energy from exci...
8/48
HalfHalf--LifeLife
Radioactive decay is a random process (Poisson
Statistics).
Mother radionuclide -> Daughter (radio...
10/48
Imaging Radioactive EmissionImaging Radioactive Emission
Nuclear Medicine (e.g., SPECT) is based on emission data fr...
11/48
Nuclear Medicine ImagingNuclear Medicine Imaging
Inject
Radioactive
Material Detect
Radioactivity
12/48
Study of Function and PhysiologyStudy of Function and Physiology
Common radiologic imaging (x-ray, ultrasonography, ...
13/48
Production of Radiopharmaceuticals (aka (Production of Radiopharmaceuticals (aka (Radio)tracersRadio)tracers))
Radio...
14/48
CyclotronCyclotron
16/48
ScintillatorScintillator
From Wikipedia,
A scintillator is a device or substance that absorbs high energy (ionizing)...
17/48
Scintillation Photon DetectionScintillation Photon Detection
Scintillation photons are detected by photon detectors ...
18/48
Emission TomographyEmission Tomography
Tomography: [Gk tomos section, cut; Gk graphikos, to write] Process of
imagin...
19/48
Image Reconstruction
(Backprojection)
Tomographic
Reconstruction
Rotational SPECTRotational SPECT
Data Acquisition
(...
20/48
Commercial SPECT(/CT) ScannersCommercial SPECT(/CT) Scanners
GE Millennium VG ADAC Cardio 60
(Philips Medical)
21/48
Positron Emission Tomography (PET)Positron Emission Tomography (PET)
BGO or LSO Crystal
Photomultiplier Tubes
Annihi...
22/48
Commercial PET(/CT) ScannersCommercial PET(/CT) Scanners
SiemensGeneral Electric
24/48
CollimationCollimation
To Data Acquisition Electronics
Photomultiplier
Tubes
Light Guide
NaI(Tl) Crystal
Collimator
...
25/48
ScatterScatter
Scintillation
Camera
Scatter Radiation
Scintillation
Camera
Imaging Concept
26/48
Photon Attenuation
Scintillation
Camera
AttenuationAttenuation
Scintillation
Camera
Imaging Concept
28/48
PositronPositron ““β+
”” EmissionEmission
eenp ν++→ +
Z
A
X +1.02MeV→Z−1
A
Y + β+
+ν
γ
β+
Z−1
A
Y
Z
A
X
2moc2
=1.02M...
29/48
Examples of Positron Emitters in Nuclear MedicineExamples of Positron Emitters in Nuclear Medicine
Rb82 rubidium fro...
30/48
PositronPositron--Electron AnnihilationElectron Annihilation
γ
Eγ = 511 keV
γ
Eγ = 511 keV
Positron Emission (e.g., ...
31/48
Coincidence Logic (Electronic Collimation)Coincidence Logic (Electronic Collimation)
BGO or LSO Crystal
Photomultipl...
33/48
TomographicTomographic (SPECT and PET) Image Reconstruction(SPECT and PET) Image Reconstruction
Tomographic images a...
34/48
Filter projections removes
blurring of backprojection
process
Filter (edge-sharpen
projections prior to
backprojecti...
35/48
Iterative Reconstruction Algorithm (MLEM or OSEM)Iterative Reconstruction Algorithm (MLEM or OSEM)
ANALYTIC ALGORITH...
36/48
Stopping
Conditions
Measured
Projection Data
Projector
Attenuation Map
Image
Estimate
Comparator
Corrector
Final
Ima...
37/48
Iterative EstimatesIterative Estimates
Iter0
Iter1
Iter2
Iter4
Iter8
Iter16
Iter32
Iter64
Object
39/48
Some of Tumor Specific RadiopharmaceuticalsSome of Tumor Specific Radiopharmaceuticals
RADIOPHARMACEUTICAL
18F-fluor...
40/48
Glucose
18FDG
18FDG-6-PO4
Vascular
Compartment
Metabolic Compartment
hexokinase
G-6-P
ECF
Glycogen
G-1-PO4
G-6-P
F-6...
41/48
1818
FF--FDGFDG--PET ScanPET Scan
*Data courtesy of Tom Lewellen, Ph.D., University of Washington
18F-Fluorodeoxyglu...
42/48
1818
FF--FLT (FLT (fluorothymidinefluorothymidine) PET) PET
FLT is a cell proliferation marker. The figures show tum...
43/48
99m99m
TcTc--MDP Bone ScanMDP Bone Scan
Normal Metastatic Prostate Cancer
44/48
99m99m
TcTc--sestaMIBI SPECTsestaMIBI SPECT
http://www.gehealthcare.com/usen/fun_img/nmedicine/myosight/products/img...
45/48
111111
InIn--ProstaScint SPECT/CTProstaScint SPECT/CT
46/48
Bone scintigraphy reveals changes in bone metabolism (bone turnover or
blood flow) rather than changes in bone struc...
47/48
99mTc99mTc--MDP to Image Stress FractureMDP to Image Stress Fracture
Pain in the right foot for three weeks caused b...
48/48
Skeletal muscle activity
measurements by 18F-FDG PET
(glucose metabolism) in runners.
Useful imaging technique for:
...
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Nuclear Medicine Imaging (SPECT and PET) Techniques Nuclear ...

  1. 1. Nuclear Medicine Imaging (SPECT and PET) TechniquesNuclear Medicine Imaging (SPECT and PET) Techniques and Applicationsand Applications Youngho Seo, PhD Center for Molecular and Functional Imaging UCSF Department of Radiology
  2. 2. 2/48 Outline of This LectureOutline of This Lecture Radioactivity Types of decay Gamma radiation, source of signals for Nuclear Medicine Transmission vs. emission What is emission? Study of function and physiology Production of radiotracers How data are acquired Scintillators, photodetectors (e.g., photomultiplier tubes) Gamma camera, SPECT, PET SPECT acquisitions Collimation, scatter, attenuation PET acquisitions Positron-electron annihilation, coincidence logic Image reconstruction Applications (Cancer and Musculoskeletal)
  3. 3. 3/48 Four Forces (Interactions) and Their MediatorsFour Forces (Interactions) and Their Mediators Okay. Then, electromagnetic force is carried by “photons”. In other words, photons == electromagnetic radiation that involves interactions of leptons (electrons and positrons in most cases). – This is what we are interested in the most for Nuclear Medicine. Figure from The Particle Adventure (particleadventure.org)
  4. 4. 4/48 Radioactive DecaysRadioactive Decays Spontaneous Fission Little importance in nuclear medicine Alpha (α) Decay Little importance in nuclear medicine Beta (β) Decay β- (electron) emission β+ (positron) emission β- (electron) capture Gamma (γ) Decay: γ (gamma-ray) radiation Isomeric transition Internal conversion
  5. 5. 5/48 BetaBeta++ (Positron) Emission(Positron) Emission These mostly proton-rich (except 124I) radionuclides are used in positron imaging (a.k..a. Positron Emission Tomography or PET, in short). e e e e e e e e ν ν ν ν ++→ ++→ ++→ ++→ ++→ + + + + + NO NC OF YX 15 7 15 8 11 7 11 8 18 8 18 9 A 1-Z A Z eeeeννννeeeennnnpppp
  6. 6. 6/48 Gamma EmissionGamma Emission -- Isomeric Transition (IT)Isomeric Transition (IT) Isomer: Nucleus with different arrangements Ground states: The most stable energy states Excited states: Arrangements are so unstable that there is only a short transient time (less than 10-12 sec) becoming ground states. Metastable states: Arrangements are unstable, but relatively long-lived (sometimes up to several hours) before becoming ground states. γ1 (IC) γ2 (IT) γ3 (IC) Tc-99m (6 h half-life) 142 keV 140 keV 0 keV
  7. 7. 7/48 AlternativeAlternative -- Internal Conversion (IC)Internal Conversion (IC) Internal Conversion (IC): Energy from excited nucleus is transferred directly to an orbital electron. When the electron is ejected, the vacancy is filled by an electron from an outer shell followed by characteristic x-ray. pp nn K shell L shell x-ray
  8. 8. 8/48 HalfHalf--LifeLife Radioactive decay is a random process (Poisson Statistics). Mother radionuclide -> Daughter (radio)nuclide NdtdN λ=− / N: The number of radioactive atoms at time t. λλλλ: Decay constant, Radionuclide-specific λtλtλtλt 0000eeeeAAAAA(t)A(t)A(t)A(t) − − = = t eNtN λ 0)( A: Activity = λλλλN Time required to reduce its initial activity (A0) to a half (1/2*A0) 0.693/λ0.693/λ0.693/λ0.693/λtttt1/21/21/21/2 = = − 2/1 00 2 1 t eAA λ
  9. 9. 10/48 Imaging Radioactive EmissionImaging Radioactive Emission Nuclear Medicine (e.g., SPECT) is based on emission data from radioactive materials injected in the body. Nuclear signals penetrated through the body are detected and reconstructed to form images. X-Ray Tube X-Ray Detectors To Data Acquisition Electronics Patient with Radioactivity Transmission ‘through’ Emission ‘from’
  10. 10. 11/48 Nuclear Medicine ImagingNuclear Medicine Imaging Inject Radioactive Material Detect Radioactivity
  11. 11. 12/48 Study of Function and PhysiologyStudy of Function and Physiology Common radiologic imaging (x-ray, ultrasonography, CT, or MRI) Basically transmission imaging Morphological, structural information The images in anatomical imaging consist of true physical parameters (e.g., CT number in CT is directly proportional to photon attenuation coefficient in the imaged object.). Nuclear Medicine Imaging (scintigraphy, SPECT, or PET) Basically emission imaging Physiologic, metabolic, biochemical information Use of pharmaceutical (physiology or function) chemically labeled with radioactive elements: radiopharmaceutical (or radiotracer)
  12. 12. 13/48 Production of Radiopharmaceuticals (aka (Production of Radiopharmaceuticals (aka (Radio)tracersRadio)tracers)) Radioactive elements (radionuclides) are produced by: Natural occurrence, but rarely Nuclear reactors (bombarding neutron beams to stable nuclides) Nuclear fission (as a product) Cyclotron (bombarding accelerated charged particles to stable nuclides) A radioactive compound used for the diagnosis and therapeutic treatment of human diseases. Radiopharmaceutical = Radionuclide + Pharmaceutical For example, 99mTc-MDP = 99mTc (radionuclide) + MDP (methylene diphosphonate) Used in skeletal scintigraphy primarily for detection of neoplasm, infection, or trauma. 18F-FDG = 18F (radionuclide) + FDG (fluorodeoxyglucose) Used in positron emission tomography primarily to diagnose many brain diseases, measure regional brain function, measure myocardial viability, and diagnose or stage a variety of cancers.
  13. 13. 14/48 CyclotronCyclotron
  14. 14. 16/48 ScintillatorScintillator From Wikipedia, A scintillator is a device or substance that absorbs high energy (ionizing) electromagnetic or charged particle radiation then, in response, fluoresces photons at a characteristic Stokes-shifted (longer) wavelength, releasing the previously absorbed energy. Most scintillators are inorganic crystals. Examples are: NaI(Tl) (commonly used in gamma cameras), BaF2, CsI, BGO (bismuth germanate, commonly used in PET), LaBr3, LuI3, etc. Incident nergetic particles (photons or charged particles) Scintillator Scintillation photons
  15. 15. 17/48 Scintillation Photon DetectionScintillation Photon Detection Scintillation photons are detected by photon detectors such as photomultiplier tubes (PMTs). radioactive photon photocathode dynode dynode dynode anode High Voltage To Electronics Scintillation photons
  16. 16. 18/48 Emission TomographyEmission Tomography Tomography: [Gk tomos section, cut; Gk graphikos, to write] Process of imaging the structures along a plane through the body. Single Photon Emission (Computed) Tomography (SPECT or SPET) Positron Emission Tomography (PET)
  17. 17. 19/48 Image Reconstruction (Backprojection) Tomographic Reconstruction Rotational SPECTRotational SPECT Data Acquisition (Projection) Projection Data (Sinogram) Reconstructed Data (Tomogram) Data Acquisition
  18. 18. 20/48 Commercial SPECT(/CT) ScannersCommercial SPECT(/CT) Scanners GE Millennium VG ADAC Cardio 60 (Philips Medical)
  19. 19. 21/48 Positron Emission Tomography (PET)Positron Emission Tomography (PET) BGO or LSO Crystal Photomultiplier Tubes Annihilating Photons (511 keV) Ring detector modules (crystal + PMT + read-out electronics) will collect angular projections simultaneously.
  20. 20. 22/48 Commercial PET(/CT) ScannersCommercial PET(/CT) Scanners SiemensGeneral Electric
  21. 21. 24/48 CollimationCollimation To Data Acquisition Electronics Photomultiplier Tubes Light Guide NaI(Tl) Crystal Collimator Patient with Radionuclide (View from top/bottom)
  22. 22. 25/48 ScatterScatter Scintillation Camera Scatter Radiation Scintillation Camera Imaging Concept
  23. 23. 26/48 Photon Attenuation Scintillation Camera AttenuationAttenuation Scintillation Camera Imaging Concept
  24. 24. 28/48 PositronPositron ““β+ ”” EmissionEmission eenp ν++→ + Z A X +1.02MeV→Z−1 A Y + β+ +ν γ β+ Z−1 A Y Z A X 2moc2 =1.02MeV
  25. 25. 29/48 Examples of Positron Emitters in Nuclear MedicineExamples of Positron Emitters in Nuclear Medicine Rb82 rubidium from 82Sr generator 3 13 NH ammonia labeledO −15 water Tissue Perfusion F18 fluorodeoxyglucose C11 palmitate C11 acetate Tissue Metabolism
  26. 26. 30/48 PositronPositron--Electron AnnihilationElectron Annihilation γ Eγ = 511 keV γ Eγ = 511 keV Positron Emission (e.g., 18F, 11C, 15O) Electron in object (e.g., cancer cells) Positron, ββββ+ Electron, ββββ-
  27. 27. 31/48 Coincidence Logic (Electronic Collimation)Coincidence Logic (Electronic Collimation) BGO or LSO Crystal Photomultiplier Tubes Annihilating Photons (511 keV) Energy Discrimination And Coincidence Timing Electronics
  28. 28. 33/48 TomographicTomographic (SPECT and PET) Image Reconstruction(SPECT and PET) Image Reconstruction Tomographic images are generated from projection data using reconstruction algorithms. Analytic method: Filtered backprojection Statistical method: Iterative Maximum Likelihood Expectation Maximization (MLEM) or Ordered Subsets Expectation Maximization (OSEM)
  29. 29. 34/48 Filter projections removes blurring of backprojection process Filter (edge-sharpen projections prior to backprojection Filtered backprojection Simple backprojection FilteredFiltered BackprojectionBackprojection (FBP)(FBP)
  30. 30. 35/48 Iterative Reconstruction Algorithm (MLEM or OSEM)Iterative Reconstruction Algorithm (MLEM or OSEM) ANALYTIC ALGORITHMS (Filtered Backprojection) Radionuclide Distribution Projection Data Data Acquisition Radionuclide Distribution Projection Data ITERATIVE ALGORITHMS (ML-EM) Data Acquisition Tomogram Backprojection (Tomographic Reconstruction) Projection (Models image acquisition process) Tomogram Backprojection (Tomographic Reconstruction) The tomogram is a mathematical repre- sentation of the radio- nuclide distribution within the patient
  31. 31. 36/48 Stopping Conditions Measured Projection Data Projector Attenuation Map Image Estimate Comparator Corrector Final Image Initial Image Estimate Iterative Image ReconstructionIterative Image Reconstruction
  32. 32. 37/48 Iterative EstimatesIterative Estimates Iter0 Iter1 Iter2 Iter4 Iter8 Iter16 Iter32 Iter64 Object
  33. 33. 39/48 Some of Tumor Specific RadiopharmaceuticalsSome of Tumor Specific Radiopharmaceuticals RADIOPHARMACEUTICAL 18F-fluorodeoxyglucose (FDG) 18F-fluorotamoxifen 18F-estadiol 11C-choline 11C-methionine 111In-octreotide 111In-Oncoscint 99mTc-174H.64 99mTc-IMMU-4-Fab’ 99mTc-methylene diphosphonate (MDP) 111In-ProstaScint 111In-antiCEA 123I-vasoactive intestinal peptide 131I-metaiodobenzylguanidine TUMOR SITE most tumors breast breast prostate glioma, lymphoma, lung neuroendocrine, lymphoma colorectal, ovarian head/neck breast bone prostate colorectal lung, stomach, pancreas, colon neuroblastoma
  34. 34. 40/48 Glucose 18FDG 18FDG-6-PO4 Vascular Compartment Metabolic Compartment hexokinase G-6-P ECF Glycogen G-1-PO4 G-6-P F-6-P CO2 + H20 Glucose Glucose CapillaryMembrane 18FDG18FDG hexokinase G-6-P Phosphorylase 'a' “FDG, glucose analogue… …FDG-6-phosphate does not undergo glycolysis, and does not enter the fructose-pentose shunt or glycogen synthesis pathway… …cellular FDG uptake reflects the overall rate of transmembranous exchange of glucose…” (Medcyclopaedia provided by Amersham Health) 22--deoxydeoxy--2[2[1818 F]fluorodeoxyglucose (FDG) metabolismF]fluorodeoxyglucose (FDG) metabolism
  35. 35. 41/48 1818 FF--FDGFDG--PET ScanPET Scan *Data courtesy of Tom Lewellen, Ph.D., University of Washington 18F-Fluorodeoxyglucose (FDG)
  36. 36. 42/48 1818 FF--FLT (FLT (fluorothymidinefluorothymidine) PET) PET FLT is a cell proliferation marker. The figures show tumor uptake in patient’s tongue.
  37. 37. 43/48 99m99m TcTc--MDP Bone ScanMDP Bone Scan Normal Metastatic Prostate Cancer
  38. 38. 44/48 99m99m TcTc--sestaMIBI SPECTsestaMIBI SPECT http://www.gehealthcare.com/usen/fun_img/nmedicine/myosight/products/imgcasestudy_new.html
  39. 39. 45/48 111111 InIn--ProstaScint SPECT/CTProstaScint SPECT/CT
  40. 40. 46/48 Bone scintigraphy reveals changes in bone metabolism (bone turnover or blood flow) rather than changes in bone structure. Structural information is not present. So, bone scintigraphy cannot replace any other structural imaging (x-ray radiography, CT, or MRI). Very sensitive (because it reveals the metabolism of the bone), but usually specificity is very low. However, Can be used (and is primarily useful) for: Stress fractures (the result of repeated low-level impact) when radiography is normal. Confirmation of fracture when radiography is normal. Infection (osteomyelitis) when combined with gallium scan or radiolabeled white blood cell (WBC) scan. 99m99m TcTc--MDP or 18FMDP or 18F--Fluoride in Musculoskeletal ApplicationsFluoride in Musculoskeletal Applications
  41. 41. 47/48 99mTc99mTc--MDP to Image Stress FractureMDP to Image Stress Fracture Pain in the right foot for three weeks caused by stress fracture. From http://www.uhrad.com/spectarc/nucs012.htm
  42. 42. 48/48 Skeletal muscle activity measurements by 18F-FDG PET (glucose metabolism) in runners. Useful imaging technique for: Sports science and rehabilitation medicine Index for proper training of a particular muscle group 201Tl-SPECT can be used for a similar application. However, 201Tl, a Potassium analog, is directly proportional to blood flow. It has been reported that blow flow in the leg during strenuous exercise increases corresponding to an increase of cardiac output. Tashiro M, et al. J Nucl Med. 1999;40:70-76. Direct Musculoskeletal Measurements byDirect Musculoskeletal Measurements by 1818 FF--FDG PETFDG PET

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