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Functional magnetic resonance imaging or functional MRI (fMRI) measures brain activity by detecting changes associated with blood flow. [1][2] This technique relies on the fact that cerebral blood flow and neuronal activation are coupled. When an area of the brain is in use, blood flow to that region also increases. [3]
The first study of the human brain at 3.0 T was published in 1994, [13] and in 1998 at 8 T. [14] Studies of the human brain have been performed at 9.4 T (2006) [15] and up to 10.5 T (2019). [16] Paul Lauterbur and Sir Peter Mansfield were awarded the 2003 Nobel Prize in Physiology or Medicine for their discoveries concerning MRI.
Arterial spin labeling (ASL), also known as arterial spin tagging, is a magnetic resonance imaging technique used to quantify cerebral blood perfusion by labelling blood water as it flows throughout the brain. ASL specifically refers to magnetic labeling of arterial blood below or in the imaging slab, without the need of gadolinium contrast. [1]
Magnetic resonance angiography (MRA) is a group of techniques based on magnetic resonance imaging (MRI) to image blood vessels. Magnetic resonance angiography is used to generate images of arteries (and less commonly veins) in order to evaluate them for stenosis (abnormal narrowing), occlusions, aneurysms (vessel wall dilatations, at risk of rupture) or other abnormalities.
Resting state fMRI (rs-fMRI or R-fMRI) is a method of functional magnetic resonance imaging (fMRI) that is used in brain mapping to evaluate regional interactions that occur in a resting or task-negative state, when an explicit task is not being performed. [3][4] A number of resting-state brain networks have been identified, one of which is the ...
Pneumoencephalography (sometimes abbreviated PEG; also referred to as an " air study ") was a common medical procedure in which most of the cerebrospinal fluid (CSF) was drained from around the brain by means of a lumbar puncture and replaced with air, oxygen, or helium to allow the structure of the brain to show up more clearly on an X-ray image.
Functional magnetic resonance spectroscopy of the brain ( fMRS) uses magnetic resonance imaging (MRI) to study brain metabolism during brain activation. The data generated by fMRS usually shows spectra of resonances, instead of a brain image, as with MRI. The area under peaks in the spectrum represents relative concentrations of metabolites.
The brain's magnetic field, measuring at 10 femto tesla (fT) for cortical activity and 10 3 fT for the human alpha rhythm, is considerably smaller than the ambient magnetic noise in an urban environment, which is on the order of 10 8 fT or 0.1 μT. The essential problem of biomagnetism is, thus, the weakness of the signal relative to the ...