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Usually, these field gradients are modulated to sweep across the region to be scanned, and it is the almost infinite variety of RF and gradient pulse sequences that gives MRI its versatility. Change of field gradient spreads the responding FID signal in the frequency domain, but this can be recovered and measured by a refocusing gradient (to ...
Magnetic resonance imaging (MRI) is a medical imaging technique used in radiology to generate pictures of the anatomy and the physiological processes inside the body. MRI scanners use strong magnetic fields, magnetic field gradients, and radio waves to form images of the organs in the body.
Gradient echo is a magnetic resonance imaging (MRI) sequence that has wide variety of applications, from magnetic resonance angiography to perfusion MRI and diffusion MRI. Rapid imaging acquisition allows it to be applied to 2D and 3D MRI imaging.
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. [2] [3]
A pulsed field gradient is a short, timed pulse with spatial-dependent field intensity. Any gradient is identified by four characteristics: axis, strength, shape and duration. Pulsed field gradient (PFG) techniques are key to magnetic resonance imaging, spatially selective spectroscopy and studies of diffusion via diffusion ordered nuclear ...
Magnetic field gradient: High gradient focus of magnetic resonance in a smaller volume (smaller point spread function), results in a better spatial resolution. The gradients for MRM are typically 50 to 100 times those of clinical systems. However, the construction of radio frequency (RF) coils used in MRM does not allow ultrahigh gradients.
Titanium and its alloys can heat from the radiofrequency field, as well as the switched gradient field (due to Faraday's law of magnetic induction). Implants with metallic or electrically conductive parts may interact with the switched gradient and/or RF fields used in MRI, causing trauma or burns. [16]
Unlike T 2, T 2 * is influenced by magnetic field gradient irregularities. The T 2 * relaxation time is always shorter than the T 2 relaxation time and is typically milliseconds for water samples in imaging magnets. T 2 *-weighted imaging can be created as a postexcitation refocused gradient echo (GRE) sequence with small