Intro Flashcards
What are the components of a MRI scanner?
3 major components:
super-conducting magnet (3Tesla)
set of 3 gradient coils
radio frequency receiver&transmitter
resonance freq of the body?
128MHz
How to create an image of the body using the gradient coils?
Based on the (resonance?) frequency of the MRI scanner spatially dependent, determine from the frequency of the signal where the signal comes from
Where can MRI signals can be used?
In imaging
Voxel?
Volume Pixel
Voxel size ?
FOV/ matrix size (fov -field of view; matrix - number of elements we have in the slice)
what is imaging?
generate section or slices
Magnetic resonance can do both normal imaging and functional imaging , give some examples of normal and functional imaging.
conventional/normal:T1 weighting, T2 weighting, proton weighting
functional:Difussion weighting, angio weighting, velocity weighting
How long to generate an MRI image?
10ms-8min, time is proportional with quality
MR for dynamic imaging used for?
follow motion-heartbeat
follow contrast agent distribution-perfusion
T1 weighting vs T2 weighting
T1 good high res. anatomical resolution; T2 enhancing pathology
Limitations of MRI
Low spatial resolution:0.4-3mm(size of voxels)
Long scan time:50ms-5 min/slice
sensitive to motion
Low sensitivity-many spins/molecules needed for reliable signal
Advantages of MRI
High resolution\
Non invasive
Varying the contrast of the image
Vary the slice orientation
Add physiological/functional measurements
MRI vs ultrasound
both are harmless
Ultrasound: cheaper, smaller, faster
MRI:Superior image quality, possibility to vary contrast, possibility of functional examinations
MRI vs CT
CT: faster, better spatial res.,
MRI: not harmful(no ionizing radiation), possibility to vary contrast, possibility of functional examinations
