Positron Emission Tomography PET

an noninvasive, three-dimensional tomographic imaging procedure that involves the administration of radioactive molecules to demonstrate the biochemical function of the body’s organs and tissues

PET

This nuclear imaging technique images the __ of the radioactive materials as they move into and out of tissues.

distribution and kinetics

___ images of the distribution of the radioactive tracer in the body is produced.

3D tomographic

PET is function study of ___

physiology

CT/MRI/ ultrasound/ dx xray are____ studies

structural

__ studies determine whether organs and tissues are healthy or diseased.

Biochemical and Functional

PET can often detect __ even before the onset of symptoms.

abnormal function

Detection of disease in __ can aid physicians in planning the most appropriate care for their patient.

early stage

3 factors distinguish PET from all radiologic procedures and from other nuclear imaging procedures:
1. The gathered images are __ images, because they are related to a particular physiological parameter such as blood flow or metabolism.

functional or parametric

3 factors distinguish PET from all radiologic procedures and from other nuclear imaging procedures:

2. Images created are by the simultaneous detection of a __ radiation that results from positron decay.

pair of annihilation

3 factors distinguish PET from all radiologic procedures and from other nuclear imaging procedures:

3. The __used is specifically chosen because of it similarity to naturally occurring biochemical constituents of the human body.

radiotracer

PET is similar to __ in that they both use radioactive compounds (tracers) that are administered to the patient by injection or inhalation.

Nuclear Medicine

But, unlike NM, PET uses tracers that emit __during the radioactive decay process.

positrons

PET uses three naturally occurring elements (__) that are easily incorporated into a wide variety of biochemical compounds.

oxygen, nitrogen, and carbon

atomic number 8

atomic mass 16

oxygen

atomic number 7

atomic mass 14.01

Nitrogen

atomic number 6

atomic mass 12.01

Carbon

atomic number 9

atomic mass 19

Flourine element

__is also used and can be substituted for the hydrogen atom present in many biochemical compounds.

Fluorine

Radiotracers are made by synthesizing compounds with radioactive isotopes of these elements.
When these elements are attached to other compounds to form specific radioactive tracers, they can measure processes at the __ such as: glucose metabolism, oxygen utilization, and tissue perfusion.

cellular level

A given compound acts as a tracer of a ____

specific biochemical process

__ is identical in mass to an electron, but the positron
possesses a positive charge instead of a negative charge.

The positron

The decay of a positron occurs in __radioisotopes.

unstable

Positrons are emitted from the nucleus with very ___.

high velocity and kinetic energy

Interactions with the surrounding tissue __ the positron until all of it’s kinetic energy is lost.

rapidly slows

Once all of the kinetic energy is lost, the positron combines momentarily with an _.

electron

The combination of particles results in __ and the combined positron-electron mass of 1.022MeV is transformed into 2 equal-energy 511-keV photons, which are emitted 180 degrees from each other.

total annihilation (disintegration)

Using __
~normal to see brain consume b/c a great deal of glucose is
used by the brain

18F-FCG

Neurology
Epilepsy
For patients that are not responding to __, PET can be used to identify the seizure sites in epileptic patients.

drug therapy

Neurology
Epilepsy

___ is used to study this disorder.

FDG (sugar tracer)

Neurology
Epilepsy

Patient does not have to be __ at the time of the scan for PET to identify seizure sites.

experiencing a seizure

Neurology
Epilepsy

If a seizure occurs during the PET scan, the attained images will show an __ utilization at the seizure site.

increase in sugar

Neurology
Epilepsy

If a seizure is NOT occurring at the time of the PET scan, the images will show a ____ utilization in the area of the seizure site.

decrease in sugar

Neurology cont’
Dementia
PET can be used to confirm a diagnosis of __ and monitor the effects of treatment of the disease.

Alzheimer’s disease

Neurology cont’
Dementia

___ naturally decreases uniformly in the brain during the normal aging process.

Glucose metabolism

Neurology cont’
Dementia

For Alzheimer’s patients, glucose metabolism is __ in several specific areas of the brain.

dramatically decreased

Neurology cont’
Dementia

Therefore, PET uses FDG to measure glucose
metabolism to aid in the __of Alzheimer’ disease.

diagnosis