Structural Neuroimaging
- Created by: Victoria_Ofume
- Created on: 21-11-20 16:05
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- Structural Imaging Techniques
- History
- Can be done with MRI and CT as well as X-ray.
- 1909-52 Areas had been discovered and split into 11 histological categories.
- As of 2016, there are 180 areas and they're grouped based on structure and function.
- X-RAY
- The origin of structural imaging.
- Works by measuring tissue density.
- Photons are emitted, they pass through the different tissues. Based on tissue density, photons are deflected or absorbed at different degree. They are then recorded as they leave the body onto the film.
- Computed Tomography (CT)
- X-RAY beams are passed through the head at different angles (multi-planar)
- The sensors measure radiation absorbed by tissues. The difference in tissue absorption is used to form cross-sectional images (tomograms)
- Tomograms can be 3D rendered and can be used with contrast agents to show different tissues.
- Ultrasound
- Locations of surfaces between and within different tissues are discovered using sound waves.
- They measure the time between emission of the ultrasonic pulse and the echo created when the surface reflects the pulse.
- Magnetic Resonance Imaging (MRI)
- Uses radio frequency waves to probe tissue structure without the need for exposure to ionising radiation.
- the RF signal resinates with the spin of the protons in a defined tissue and the waves in the coil current are converted into a density map using fourier transorm
- A magnetic field of 3 TESLA, lines up protons in water or other molecules, a radio signal then flips the lined up protons causing them to spin out of line.
- The radio signal is turned off and the protons realign giving off electromagnetic energy. This energy is measured with a coil and then converted into current.
- TR=Repetition Time. This is the amount of time between successive pulse sequences applied to the same slice.
- TE=Time of Echo. This is the time between the delivery of RF pulse and the delivery of RF pulse and the receipt of the echo signal
- T1 weighted images have short TE and TR times while T2 weighted images have longer TE and TR times. CSF will appear dark on T1 and bright on T2.
- Fluid Inversion Attenuated Recovery (FLAIR) is similar to T2 but the TE and TR are very long. In this method, CSF appears dark and abnormalities appear bright.
- T1 weighted images have short TE and TR times while T2 weighted images have longer TE and TR times. CSF will appear dark on T1 and bright on T2.
- TE=Time of Echo. This is the time between the delivery of RF pulse and the delivery of RF pulse and the receipt of the echo signal
- Uses radio frequency waves to probe tissue structure without the need for exposure to ionising radiation.
- History
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