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Resting state fMRI (rs-fMRI or R-fMRI), also referred to as task-independent fMRI or task-free 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.
Heat causes electrons to move around and distort the current in the fMRI detector, producing thermal noise. Thermal noise rises with the temperature. It also depends on the range of frequencies detected by the receiver coil and its electrical resistance.
RF pulses and precessional frequencies of MRI instruments occupy the same frequency bandwidth as common sources such as TV, radio, fluorescent lights and computers. Stray RF signals can cause various artifacts. Narrow-band noise is projected perpendicular to the frequency- encoding direction. Broadband noise disrupts the image over a much ...
Noise in fMRI can arise from a variety of different factors including heart beat, changes in the blood brain barrier, characteristics of the acquiring scanner, or unintended effects of analysis. Some researchers have proposed that the variability in functional connectivity in fMRI studies is consistent with the variability that one would expect ...
Functional magnetic resonance imaging (fMRI) is affected by noise. [20] Noise that is present during scanning can impact the integrity of an image by introducing an aspect of uncertainty through noise. More research is needed to know whether this noise is specifically synaptic noise, or one of the other types.
Modern 3 Tesla clinical MRI scanner.. Magnetic resonance imaging (MRI) is a medical imaging technique mostly used in radiology and nuclear medicine in order to investigate the anatomy and physiology of the body, and to detect pathologies including tumors, inflammation, neurological conditions such as stroke, disorders of muscles and joints, and abnormalities in the heart and blood vessels ...
In single-voxel fMRS the selection of the volume of interest (VOI) is often done by running a functional magnetic resonance imaging (fMRI) study prior to fMRS to localize the brain region activated by the task. Single-voxel spectroscopy requires shorter acquisition times; therefore it is more suitable for fMRS studies where high temporal ...
The concerns in pregnancy are the same as for MRI in general, but the fetus may be more sensitive to the effects—particularly to heating and to noise. The use of gadolinium-based contrast media in pregnancy is an off-label indication and may be administered only in the lowest dose required to provide essential diagnostic information. [51]