Imaging in inflammatory disorders & infection IA % + Flashcards
1
Q
Radionuclide imaging pic
A
2
Q
Radiography pic 2
A
3
Q
Gamma radiation
A
- Gamma rays occur due to radioactive decay of unstable isotopes
- High energy, high frequency, very similar properties to x-rays
4
Q
Properties of an ideal isotope
A
- Half-life similar to length of examination
- Gamma emitter, rather than a or b
- Energy of g rays should be 50-300 keV
- Radionuclide should be readily available at hospital site
- Easily bound to pharmaceutical component
- Radiopharmaceutical should be simple to prepare
- Radiopharmaceutical should be eliminated in similar half-time to duration of examination
5
Q
99mTechnecium
A
- hydroxy-diphosphonate ⇒ bone
- dimercapto-succinic acid ⇒ kidney
- hexamethyl-propine amine oxime ⇒ brain
- macroaggregated albumin ⇒ lung
6
Q
Single photon emission computed tomography - SPECT
A
- CT version of nuclear medicine
- Gamma cameras rotate around area of interest
- Routinely used for brain and cardiac studies
- Can be applied to any site of interest in other studies e.g. spine in bone scan or in lung scintigraphy
7
Q
Positron Emission Tomography
A
- Molecular imaging
- Uses radionuclides that decay by positron emission – proton ⇒ neutron + positron
- These can be used to image biologically interesting processes
- Can be used for absolute quantitation but requires arterial sampling
- All scanners now PET CT
8
Q
Half lives pic
A
9
Q
Physiological FDG (fluorodeoxyglucose ) uptake
A
- Brain
- Myocardium (muscular tissue of heart)
- Stomach (arrow)
- Liver
- Spleen
- Colon
- Urinary tract
10
Q
Radiation – risks vs benefits
A
Main risk is ionising radiation
•Risk of inducing fatal cancer e.g. CT abdomen & pelvis = 1:1600 (but risk is 1:4 for population and risk is relative)
Benefits
•Diagnosis, management change, treatment) should always outweigh costs (radiation, risk to patient and staff, ££)
