Imaging in inflamm and infection Flashcards Preview

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Flashcards in Imaging in inflamm and infection Deck (14):
1

Radionuclide imaging
Positron emission tomography
Magnetic resonance imaging
Optical imaging

Molecular Imaging

2

radiopharmaceutical - gamma rays - pharmaceutical determines where the element go

patient

lead collimator - detect photon
gamma camera - move head to toe
PACS

Radionuclide imaging

3

Which rays travel further? State in order from lowest to highest.

alpha (long wavelength, energy +freq low)
beta
gamma (high penetrance, short wavelength, energy +freq high )

all of above = non-visible

4

x-ray tube

patient

digital image capture

PACS

Radiography

5

Radioactive decay of unstable isotopes

High energy, high frequency, very similar properties to x-rays

Gamma rays/ radiation

6

Properties of an ideal isotope

1/2-life similar to examination length
Gamma, rather than a/b
Energy of g rays = 50-300 keV
Radionuclide = readily available at hospital site
Easily bound to pharmaceutical component
Radiopharmaceutical should be simple to prepare + eliminated in similar half-time to duration of examination


= ideal isotope doesn't exist

7

Radioisotope - that can be attached to different bits of organ/bones (short-lived 1/2-life = 6.5 hours)
nuclear medicine
gamma

99m Technecium (Tc)

hydroxy-diphosphonate (HDP) bone

dimercapto-succinic acid (DMSA) kidney

hexamethyl-propine amine oxime (HMPAO) brain/ colon (WCS - white cell scan)

macroaggregated albumin lung

8

4 main components of gamma camera

Computer - process info - image on monitor

photomultiplier tubes - many electrons - electronic signal amplified

Scintillator (gamma absorbed - remitted as visible photon/light)

collimeter (lead walls- non-parallel rays abs - parallel pass to scintillator

9

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

Single photon emission computed tomography (SPECT)

10

Molecular imaging
Uses radionuclides that decay by positron emission – proton --> neutron + positron
Image biologically interesting processes
Absolute quantitation but requires arterial sampling
All scanners now PET CT

Positron emission tomography (PET)

11

PET radionuclides and half lives

18F 110 mins (fluorodeoxy glucose- FDG)
11N 20 min
13C 10 min
15O 2 min

12

Brain
Myocardium
Stomach (arrow)
Liver
Spleen
Colon
Urinary tract

Physiological FDG uptake

13

Patient breathe in radioactive gas - Scintigraphy

Ventilation

The ventilation scan = how well air moves and blood flows through the lungs.

Perfusion scan = blood supply (radioactive IV) through the lungs.

A ventilation and perfusion scan = detect a pulmonary embolus (blood clot in the lungs). = anti-clotting therapy given if +.

Lower amounts of radioisotope/radionuclidetaken/absorbed = problem/blockage

14

Detect pulmonary embolism
White area - normal vessels
Gray/granular area in vessels/artery - defect

Iodine Contrast