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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 ...
Phase contrast MRI (PC-MRI) is used to measure flow velocities in the body. It is used mainly to measure blood flow in the heart and throughout the body. PC-MRI may be considered a method of magnetic resonance velocimetry. Since modern PC-MRI typically is time-resolved, it also may be referred to as 4-D imaging (three spatial dimensions plus ...
The values in the phase images are constrained from -π to π so if the value goes above π it wraps to -π, inhomogeneities in the magnetic field cause low frequency background gradients. This causes all the phase values to slowly increase across the image which creates phase wrapping and obscures the image.
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.
Phase contrast MRI is one of the main techniques for magnetic resonance angiography (MRA). This 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.
Phase-contrast magnetic resonance imaging: PC-MRA: Two gradients with equal magnitude, but opposite direction, are used to encode a phase shift, which is proportional to the velocity of spins. [29] Detection of aneurysm, stenosis, or dissection (pictured). [28] ^
For a real image, the corresponding k-space is conjugate symmetric: the imaginary component at opposite k-space coordinates has the opposite sign.. In magnetic resonance imaging (MRI), the k-space or reciprocal space (a mathematical space of spatial frequencies) is obtained as the 2D or 3D Fourier transform of the image measured.
For radial data sampling, the phase- and frequency-encoding gradients are replaced by two simultaneously applied frequency-encoding gradients that rotate the Fourier lines in data space. [ 1 ] [ 3 ] In either case, repetition times are as short as 2 to 10 milliseconds, so that the use of 64 to 256 repetitions results in image acquisition times ...