- Functional magnetic resonance imaging techniques.
- This technique relies on the fact the cerebral blood flow and neuronal activation are coupled. When an area of the brain is active, blood flow to that reason also increases.
- The most robust and widely used f-MRI method is BOLD f-MRI (Blood oxygenation level development f-MRI)
- In BOLD f-MRI the imaging contrast: arises as a consequence of the higher ratio of oxy-to deoxy-Hb in local capillaries and draining vessels with brain activity.
- When bound to O2, Hb is diamagnetic in which magnetic flush is reduced resulting in the repelling of the applied magnetic field.
- When Hb is deoxygenated it is paramagnetic in which magnetic flux is increased and the applied magnetic field is attracted into the maternal.
- Thus a change in Hb oxygenation leads to change in the local distortion of a magnetic field applied to it. These signals can be recoded as (BOLD contrast).
- If deoxygenation ↓→↑ higher signal interstices (↑↑BOLD) Higher the tissue activity, ↓↓ concentration of oxyhaemoglobin →↓↓BOLD.
Application of f-MRI are growing rapidly and potentially have relevance to several aspects of otolaryngology There are:
- It can be successfully used in patient screening before cochlear implant surgery.
- It provides better spatial resolution
- There is no need of contrast enhancement.
- This can be easily performed to study audiology physiology by stimulation auditory center.
