Magnetic resonance imaging of the brain
| MRI of brain and brain stem | |
|---|---|
| Diagnostics | |
Brain MRI
|
|
| ICD-10-PCS | [1] |
| ICD-9-CM | 88.91 |
| OPS-301 code | 3-800, 3-820 |
Magnetic resonance imaging (MRI) of the nervous system uses magnetic fields and radio waves to produce high quality two- or three-dimensional images of nervous system structures without use of ionizing radiation (X-rays) or radioactive tracers.
History
The first MR images of a human brain were obtained in 1978 by two groups of researchers at EMI Laboratories led by Ian Robert Young and Hugh Clow.[1] In 1986, Charles L. Dumoulin and Howard R. Hart at General Electric developed MR angiography[2] and Denis Le Bihan, obtained the first images and later patented diffusion MRI.[3] In 1990, Seiji Ogawa at AT&T Bell labs recognized that oxygen-depleted blood with dHb was attracted to a magnetic field, and discovered the technique that underlies Functional Magnetic Resonance Imaging (fMRI).[4] In 1997, Jürgen R. Reichenbach, E. Mark Haacke and coworkers at Washington University developed Susceptibility weighted imaging.[5] The first study of the human brain at 3.0 T was published in 1994,[6] and in 1998 at 8 T.[7] Studies of the human brain have been performed at up to 9.4 T.[8]
Applications
One advantage of MRI of the brain over computed tomography of the head is better tissue contrast,[9] and it has fewer artifacts than CT when viewing the brainstem. MRI is also superior for pituitary imaging.[10] It may however be less effective at identifying early cerebritis.[11]
In the case of a concussion, an MRI should be avoided unless there are progressive neurological symptoms, focal neurological findings or concern of skull fracture on exam.[12]
In analysis of the fetal brain, MRI provides more information about gyration than ultrasound.[13]
A number of different imaging modes can be used with imaging the nervous system:
- T1: Cerebrospinal fluid is dark. T1 weighting is useful for visualizing normal anatomy.
- T2: CSF is light, but fat (and thus white matter) is darker than with T1. T2 is useful for visualizing pathology.[14]
- PD (proton density): CSF has a relatively high level of protons, making CSF appear bright. Gray matter is brighter than white matter.[15]
- FLAIR: useful for evaluation of white matter plaques near the ventricles.[16] It is useful in identifying demyelination.[17]
See also
Gallery
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T1 (note CSF is dark)
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Normal axial T2-weighted MR image of the brain.
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Wikimedia Commons has media related to Magnetic resonance imaging of the brain. |
References
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