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Pulsed radiofrequency is the technique whereby radio frequency (RF) oscillations are gated at a rate of pulses (cycles) per second (one cycle per second is known as a hertz (Hz)). Radio frequency energies occupy 1.0 × 104 Hz to 3.0 × 1011 Hz of the electromagnetic spectrum. Radio frequency electromagnetic energy is routinely produced by RF ...
Adiabatic MRI Pulses. Adiabatic radio frequency (RF) pulses are used in magnetic resonance imaging (MRI) to achieve excitation that is insensitive to spatial inhomogeneities in the excitation field or off-resonances in the sampled object. Nuclear magnetic resonance (NMR) experiments are often performed with surface transceiver coils that have ...
The Shinnar–Le Roux (SLR) algorithm is a mathematical tool for generating frequency-selective radio frequency (RF) pulses in magnetic resonance imaging (MRI). Frequency selective pulses are used in MRI to isolate a slice through the subject for excitation, inversion and saturation.
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 ...
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]
An MRI pulse sequence in magnetic resonance imaging (MRI) is a particular setting of pulse sequences and pulsed field gradients, resulting in a particular image appearance. [1] A multiparametric MRI is a combination of two or more sequences, and/or including other specialized MRI configurations such as spectroscopy.
Radiofrequency coil. Radiofrequency coils (RF coils) are the receivers, and sometimes also the transmitters, of radiofrequency (RF) signals in equipment used in magnetic resonance imaging (MRI). The MR signal in MRI is produced by the process of resonance, which is the result of radiofrequency pulses. They consist of two electromagnetic coils ...
The pulse width ( ) (or pulse duration) of the transmitted signal is the time, typically in microseconds, each pulse lasts. If the pulse is not a perfect square wave, the time is typically measured between the 50% power levels of the rising and falling edges of the pulse. The pulse width must be long enough to ensure that the radar emits ...