Imaging in Inflammatory Disorders and Infection Flashcards
What is molecular imaging?
Detects cellular changes that occur early on the course of disease
Involves an imagine device and imaging agent
In nuclear medicine the imaging agent is____
a radiotracer
Types of molecular imaging
PET, MRI and optical imaging
Gamma Camera
a gamma camera is a specialised camera that is capable of detecting a radiotracer
Creates 2D picture of the body from different angles
SPECT
this scan uses a gamma camera which rotates around the patient to detect radiotracer in the body
With a computer is creates a 3D image
SPECT can be combined with___ for greater accuracy
CT
Radionuclide imaging uses
gamma rays, lead collimator and a gamma camera
PACS
Picture Archiving and Communication System
Gamma radiation occur
due to radioactive decay of unstable isotopes
Gamma radiation is in between
Infrared and UV on the electromagnetic spectrum
Properties of ideal isotope (6)
- Half-life similar to length of examination
- Gamma emitter rather than alpha or beta
- Energy of gamma rays should be 5-300
- Radionuclide should be readily available at hospital site
- Easily bound to pharmaceutical component
- Radiopharmaceutical should be simple to prepare
- Radiopharmaceutical should be elminated in similar half-time to duration of examination
Technetium 99m
Widely used radioactive tracer isotope
Can be conjugated with different compounds to increase uptake in different tissues
Hydroxy-diphosphonate
Bone
Dimercapto-succinic acid
Kidney
hexamethyl-propine amine oxime
Brain
Macroaggregated albumin
Lung
how does a gamma camera work
Radiotracer emits gamma radiotracer
Large crystal of sodium iodide is used to detect gamma photons
This is converted to electrical signals
Analysed by computers to form an image
Single Photon Emission Computed Tomography (SPECT)
CT version of nuclear medicine
Gamma cameras rotate around area of interest
Scintigraphy
a technique in which a scintillation counter or similar detector used with a radiotracer to obtain an image of a bodily organ
HMPAO
used for labelling leukocytes to look at blood supply to the brain
Positron Emission Tomography (PET)
Uses radionuclides that decay by positron emission Proton= neutron + positron
radiotracer for PET
18 F-fluorodeoxy glucose
How does 18 F flurodeoxy- glucose work
marker of uptake of glucose, which correlates with certain types of tissue metabolisms
Physiological uptake of 18 F fluorodeoxy-glucose
Brain, heart, stomach, liver spleen, colon and urinary tract
