brief discussion about positron emission tomography

1. PET
(Positron EmissionTomography)

2. • Positron Emission Tomography (PET) is a nuclear imaging technique
that produces a 3-D image of functional processes in the body by
detecting the radiation emitted by photons .
• The system detects pairs of gamma rays emitted indirectly by
positron emitting radionuclide (tracer), which was previously
injected in body on a biologically active molecule,
• 3-D images of tracer concentration within the body are then
constructed by computer analysis.

3. A PETfacility
Scanner

4. Working
• Injection of Short lived Radioactive Isotope,
produced in cyclotron, in body most commonly
used is FDG (fluoro-2-deoxyglucose).
• Wait till tracer gets accumulated in tissues of interests.
• Subject is placed in the imaging scanner
• Tissue concentration is recorded with time.
• As isotope decays in body, it releases a positron in
body. On interaction with an electron, it produces a
pair of gamma ray photons with 511kev in 180◦
direction.

5. Detectorsmust stop high-energy gamma-rays.
PET scanner detect these photons and with the help of a
computercreatespicturesofferingdetailsonboththestructure
andfunction oforgansandtissuesinyourbody.

6. A whole body Pet
scan using FDG.

7. Applications ofPET
• PET is used in following areas.
• Neuroimaging
• Clinical oncology (medical imaging of tumors).
• Musculo-skeletal imaging
• Cardiology
• Pharmacology
• Neuropsychology

8. Neuroimaging
• The greatest benefit of PET is that it can show blood and
oxygen flow and glucose metabolism to different tissues of
working brain. These measurements help in understanding
amount of brain activity and allow us to know more about
how brain works.
• PET is superior to all other imaging techniques because of its
resolution and speed of completion.
But it has a limitation of its high cost.

9. BRAINPETSCANSDURINGLINGUISTICSACTIVITIES
By analyzing the BRAIN PET scans , we can find out that
the person has difficulty in which areas.
For e.g.

10. BrainPETscans of differentAddicts

11. Brain Diseases andPET
• Tumors, strokes and neuron damaging diseases which cause
Dementia (like Alzheimer’s disease) all cause great change in
brain metabolism which causes easily detectable changes in
PET scans.
• PET scan is most commonly used in case of certain dementias
like( Alzheimer’s Disease and Pick’s Disease) where the early
damage is not detected by using CT and MRI scans.

12. BrainPETscansofOtherDiseases

13. Oncology
• Most widely used Application of PET
• Tracer used is FDG-18.
• Highly accurate as tumor cells consume lot of glucose.
• And Tracer is a glucose analog.
• Also, tracer is bound in tumor cell once it got there until it
decays.
• Thereby, giving more accurate results.

14. PETSCANofBrainTumor
White shows the areas of high Metabolic Activity