imaging in inflammatory disorders and infection

Question 1

Positron emission tomography (PET)

Answer 1

molecular imaging- show how organs and tissues are working
uses radionuclides that decay by positron (antielectron)
these can be used to image biologically interesting processes
can be used for absolute quantitation, but requires arterial sampling
all scanners are now PET-CT (PET scans are often combined with CT scans to produce even more detailed images)

Question 2

state the properties of the ideal isotope for use in radiography

Answer 2

half-life similar to length of examination
gamma emitter, rather than alpha or beta
energy of gamma rays should be 50-300 keV
radionuclide should be readily available at hospital site
easily bound to pharmaceutical compound
radiopharmaceutical should be simple to prepare

Question 3

Risks of radiation

Answer 3

main risk is ionising radiation
risk of inducing fatal cancer (but risk 1:4)
risk to patients and staff
costly

Question 4

Benefits of radiation

Answer 4

diagnosis
management change (of inflammatory disorder/infection) and treatment should outweigh costs

Question 5

what are PET scans used for

Answer 5

Positron emission tomography (PET) scans are used to produce detailed 3-D images of the inside of the body.

Question 6

How do PET scans work?

Answer 6

PET scanners work by detecting the radiation given off by radiotracer that is injected as it collects in different parts of your body
-By analysing the areas where the radiotracer does and doesn’t build up, it’s possible to work out how well certain body functions are working and identify any abnormalities.

common radiotracer = FDG and this attaches to things like glucose so you can see where tissues that are working normally or abnormally are

Question 7

Example of a radiotracer

Answer 7

fluorodeoxyglucose (FDG) which is similar to naturally occurring glucose so your body treats it in a similar way.
e.g a concentration of FDG in the body’s tissues can help identify cancerous cells because cancer cells use glucose at a much faster rate than normal cells.

Question 8

technetium 99m

Answer 8

the most commonly used radiotracer for diagnostic purposes
it emits gamma rays which are collected by gamma camera
used in PET scans

Question 9

MR contrast agents (MRI) have a higher ____ than body tissues?

Answer 9

mass

Question 10

what is lung imaging agent

Answer 10

Tc 99m Macroaggregated Albumin

used to assess the flow of blood in the lungs

Question 11

what is a bone imaging agent

Answer 11

hydroxy- diphosphonate

Question 12

what is a brain imaging agent

Answer 12

hexamthyl-propine amine oxime

Question 13

what is a kidney imaging agent

Answer 13

dimercapto-succinic acid