2. PET/CT
• Medical Imaging
Technique
• Both systems in one
Gantry
• Aquired image combined
into a coregistered image
• Functional imaging by
PET
• Anatomical imaging by
CT-Scanner
2
By Eng. Abdulkader Helwan
3. PET/CT
• Combines the functional
information with the
anatomical detail
• Accurate anatomical
registration
• Higher diagnostic
accuracy than PET or CT
alone
3
By Eng. Abdulkader Helwan
6. PET
• Stands for positron emission tomography
• Machine that can image biological and
chemical activities
• For ex: imaging brain activity when there is a
scary event
• Active part of brain can’t be imaged using x-ray
of only CT
• It can be imaged using PET
7
By Eng. Abdulkader Helwan
7. Principles of PET
• Inject a radioactive tracer bind with glucose
• The active part of brain absorbs it more than
other inactive parts
• The radioactive tracer is:
Fluorine-18-deoxyglucose (FDG), a radionuclide
labeled glucose analogue is injected into the
organ that would be imaged
8
By Eng. Abdulkader Helwan
8. PET tracer: FDG
• Fluorodeoxyglucose is a glucose analog. Its full
chemical name is 2-fluoro-2-deoxy-D-glucose,
commonly abbreviated to FDG.
• Radioactive fluoride atom produced in a
cyclotron is attached to a molecule of glucose.
• The FDG molecule is absorbed by various
tissues just as normal glucose would be.
9
By Eng. AbdulkaderHelwan
17. CRYSTALS USED IN PET
BaF2 – Barium
Flouride(0.8ns)
BGO – Bismuth Germinate
Oxide(300ns)
LSO – Lutetium
Orthosilicate(40ns)
GSO – Gadolineum
Orthosilicate(60ns)
YLSO – Yttrium Lutetium
Orthosilicate(40ns)
17
18. Data Acqusition
• The detection of photon pairs by opposing crystals create one event(LOR)
• Millions of this event will be stored within sinograms and used to reconstructthe
image
• Spatial resolution is determined by the size of the crystal and their separation andis
typically 3-5mm
19.
20.
21.
22. Interpretation of Images
PET provides images of quantitative uptake of the radionuclide
injected that can give the concentration of radiotracer activity in
kilobecquerels per milliliter .
Methods for assessment of radiotracer uptake –
• visual inspection
• standardized uptake value (SUV)
• glucose metabolic rate
30
23. SUV
• Standardized Uptake Value
• The SUV is a semiquantitative assessment of the radiotracer uptake from a
static (single point in time) PET image.
• Malignant tumors have an SUV of greater than 2.5–3.0, whereas normaltissues
such as the liver, lung, and marrow have SUVs ranging from 0.5 to2.5.
• The SUV of a given tissue is calculated with the following formula:
24. Limitations of PET/CT
• FDG is not cancer specific and will accumulate in any
areas of high rates of metabolism and glycolysis.
• Therefore, increased uptake can be expected in all sites
of hyperactivity at the time of FDG administration (e.g.
muscles and nervous system tissues); at sites of active
inflammation or infection
28
30. Identification of distant metastatic disease
Top Tip
Evidence suggests that the
removal of a solitary adrenal
deposit at the time of resection of
the lung primary results in an
increased life expectancy.
Liver, adrenal, brain and bony
deposits are common with
lung cancer but many of the
lesions are undetected in
the course of conventional
staging
31.
32. • ASSESSMENT OF TREATMENT RESPONSE
Pretherapy and post
therapy
studies showing a
complete metabolic
response to therapy.
