Загрузил Dmitry Solovyev

Введение в Позитронно-Эмиссионную Томографию

реклама
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Introduction to PET
Dmitri Soloviev, PhD, MRSC
radiochemist,
Wolfson Brain Imaging Centre
UNIVERSITY OF
CAMBRIDGE
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Positron Emission Tomography
• PET - Diagnostic method in Nuclear
Medicine
– imaging of cancer
– organ perfusion and metabolism
– receptor studies
• Tomograph (PET camera)
– creates image of radioactivity distributed
throughout the human body
– detects g-radiation from positron
annihilation
• Radiopharmaceutical (PET radiotracer )
– delivers radioactive isotope to the tissue
• Positron Emitter (PET isotope)
– decays by emitting positrons
• Cyclotron
– produces positron-emitting isotopes
50 year-old male with colon CA
720 MBq FDG, 162 min p.i.
Data courtesy of
NC PET Imaging Center, Sacramento, USA
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
History of PET
•
•
•
•
•
•
1953 – first positron emission clinical
images (15O; 68Ga). G.Brownell, S.
Aronow, W.Sweet, Massachusets General
Hospital
1971 – first computed tomographic
images ( PET). D.Chesler, PC I , MGH
1973 – first 32-detector ring PET
camera, Robertson, Brookhaven
National Laboratory
1974 – first Human PET camera,
M.Phelps, E.Hoffmann, Washington
University.
1977- first [18F]FDG synthesis and
images. A.Wolf, J.Fowler, BNL; D.Kuhl,
A.Alavi, M.Reivich, L.Sokoloff, University
of Pennsylvania.
1985- first block detector. M.Casey,
R.Nutt, CTI
[18F]NaF
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Principle of PET
• Patient is injected with a radiotracer
• Blood distributes the radiotracer in the
body
• Cells and tissues accumulate radiotracer
• Isotope decays by positron emission, two
opposite g-quants fly out of the body
• Camera detects gamma-irradiation of
511 keV in coincidence mode at 180°
• Computer reconstructs the image of
radioactivity distribution slice by slice
• PET - tomographic image of radiotracer
distribution in the patient`s body
FDG
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Positron mode of decay
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Classical PET isotopes
Isotope
T 1/2
min
Type
of Decay
Daughter
Isotope
% b+
b+ Energy
MeV
15O
2.04
b+
15N
99.89
2.75
13N
9.96
b+
13C
100
2.22
11C
20.39
b+
11B
99.76
1.98
68Ga
67.63
b+
68Zn
89.1
2.92
18F
109.69
b+
18O
96.9
1.66
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Why use positron emission ?
• Positron produces always two
opposite g at 180°of 511 KeV energy
• Detection in coincidence mode allows
to:
– localise precisely place of radiotracer decay
– decrease the influence of background
radiation (randoms)
– quantify radioactivity in the region of
interest
• High image resolution
– is limited to the distance of positron flight in
the tissue (0.6-6 mm, depending on b+
energy)
g2
g1
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Isotope
18F
Main clinical PET applications
T1/2
Radiotracer
Action
Application
[18F]FDG
Glucose
metabolism
Oncology, cardiology,
neurology
Bone activity
Oncology
Oxidative
metabolism
Fatty acid
synthesis
Aminoacid
utilisation
Cardiology
Brain tumours
110
[18F]fluoride
[11C]acetate
11C
20
[11C]methionine
Oncology
13N
10
[13N]ammonia
Heart perfusion
Cardiology
15O
2
[15O]water
Brain perfusion
Psychology,
psychiatry, neurology
Dmitri Soloviev
Global Imaging Summit
Workshop X
[18F]FDG
October 2007,
Zurich
Use of PET-Tracers in Europe per year
Use of PET tracers
[15O]H 2O
[13N]NH 3
[11C]Meth.
18
[ F]F-DOPA
18
[ F] F15
[ O]Butanol
[15O]H2O
[11C]Flumac.
[11C]Acetate
[11C]Raclopr.
[15O]CO
very
important
most
important
FDG
H2O, NH3
11
[ C]HED
13
[ N]N 2
11
[ C]Diprenorph.
[11C]Choline
[11C]MDL100.907
[11C]Hyd-Trypt.
[11C]SCH23390
[11C]PK1195
important
Methionine
DOPA, F-
18
[ F]Thymidine
18
[ F]Uracil
11
[ C]M-Spip.
[11C]N AIB
[11C]Thyr.
[11C]WAY100.635
[18F]UdR
[18F]MPPF
less
used
11
[ C]CO2
11
[ C]DOPA
[18F]MISO
[18F]ESP
G.J.Meyer, Wart 17.Sept.1999
1
10
100
1000
10000
100000
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Example:
regional blood flow studies with 15O
•Studied: action of
odours and pheromones
on women’s brain
•PET used to measure
regional cerebral blood
flow changes
•average image of 5
subjects
•Radiotracer diffuses in
the brain following the
changes in blood flow
•2 min half-life allow
repeated injection in the
same subject
•[15O]butanol as a
radiotracer
•Other modalities (fMRI)
are available to
measure rCBF
•Requires repeated
injections for reasonable
statistics
•2 min half-life is too
short: only fast
chemistry, and on-line
delivery
•cyclotron needs to be
close to the patient
•number of studies with
oxygen-15 goes down
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Example: [18F]fluoride and FDG
18F-
fluoride
18F
FDG
Http://www.crump.ucla.edu/lpp
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Example: [11C]acetate
Carbon-11-Acetate PET imaging in
recurrent prostate cancer: Initial
experiences at the University of
Vienna
S. Wachter et al.
11C
EANM 2002 Congress, August 31 September 4, 2002
University of Vienna, Austria
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Transmission and Emission Scans
Rotating external g- source (68Ge)
• Transmission scan:
– uses external source of radioactivity
– helps to improve image quality
– quantifies absorption of g-rays in the patient's
body
– calibrates detectors
– is a supplementary tool
• Emission scan:
–
–
–
–
uses g from positron emitting radiotracer
works in coincidence mode
serves to build a PET image
is a true PET scan
g2
g1
511 KeV g- rays from injected radiotracer
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments:
fusion of images
• PET + CT
• PET+ MRI
PET image shows activity
of the cells – functional or
metabolic imaging. Very
poor anatomical structure.
CT or MRI show very fine
anatomical structures –
morphological imaging.
Combining function with
morphology provides
additional information.
University of Vienna
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments:
PET/CT scanners
PET/CT :
•combination of two cameras
•morphology & function
•CT used for transmission scan
•better quality of PET
•more sensitive
•more accurate localisation
•synergy of two modalities
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments:
PET/SPECT, microPET scanners
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments
Mobile PET
Fast PET
Emission scan
time:
27 min
ECAT ACCEL
High resolution PET
ECAT HR+
Advance NXi
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
g2
g1
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments:
microPET/MRI scanners
UNIVERSITY OF
CAMBRIDGE
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Modern PET developments:
microPET/MRI scanners
Brookhaven National Laboratory
Rat Conscious Animal PET (RatCAP)
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
Clinical PET statistics
(as of 2004)
Country
Justified need:
1 PET camera
per
1 million of habitants
1 Cyclotron
can deliver FDG
to
5-8 PET cameras nearby
or 2-4 cameras
up to 1000 km distance
Number of PET
installed
Need in
PET
% of needed
USA
600
294
204%
Belgium
19
10
198%
Sweden
4
7
196%
Switzerland
7
4
175%
Germany
80
56
143%
Spain
28
24
116%
Denmark
4
4
100%
Finland
2
2
100%
Italy
25
47
53%
Portugal
2
4
50%
Great Britain
13
42
31 %
France
11
35
31%
Russia
6
145
4%
Dmitri Soloviev
Global Imaging Summit
Workshop X
October 2007, Zurich
References
• A HISTORY OF POSITRON IMAGING. Gordon L. Brownell, 1999
Physics Research Laboratory, Massachusetts General Hospital
ftp://deas-ftp.harvard.edu/pub/tuan/pethis/pethis.pdf
• THE HISTORY OF POSITRON EMISSION TOMOGRAPHY. Ronald Nutt,
PhD, CTI PET Systems, Knoxville, TN.
Molecular Imaging and Biology, Vol. 4, No. 1, 11–26. 2002
• Let’s play PET: http://www.crump.ucla.edu/lpp
• Nuclides 2000: An electronic chart of the nuclides. Version 1.00. European
Communities 1999.
Скачать