Matches in DBpedia 2016-04 for { ?s ?p "Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to image the anatomy and the physiological processes of the body in both health and disease. MRI scanners use strong magnetic fields, radio waves, and field gradients to form images of the body.Many atomic nuclei have a property called "spin", which is associated with a magnetic dipole moment (analogous to a compass needle). All hydrogen atoms have nuclear spin, and are thus detectable by MRI. Water, having molecular formula H2O, contains a vast number of hydrogen atoms. The human body is roughly 70-percent water by mass, and most MRI scans essentially measure the spatial distribution of water in the object being imaged. The large tube into which the subject is placed is surrounded by a superconducting solenoid that produces a strong magnetic field down the length of the bore. This magnetic field aligns the nuclear spins and generates an energy difference between spins aligned with or against the field. At any feasible field strength (typical values are 1.5 or 3.0 tesla), the energy difference is in the radio frequency range of the electromagnetic spectrum. To generate an image, pulses of radio-frequency energy are emitted by antennas that excite the nuclear spin energy transition. As the spins return to equilibrium (i.e. "relax"), they emit radio-waves with a frequency dependent on the strength of the magnetic field. This RF emission is very faint (on the order of 10−12 watts), and is received by antennas close to the anatomy being imaged. By creating a precise and known gradient in the main magnetic field (with additional RF coils), nuclei at different positions will have different frequencies. The Fourier transform can then be computed, extracting the contribution of these many different frequencies from the signal. A particular frequency corresponds to the signal from water at a particular location (voxel) and an image can be reconstructed. While the hydrogen protons of water are the most often imaged nuclei, phosphorus, sodium, and carbon are sometimes used in specialty applications. There is also a wide variety of techniques that can be used while still measuring the hydrogen nuclei, including diffusion weighted MRI (DWI), contrast enhanced MRI (DCE-MRI), and functional MRI (fMRI).MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to ionizing radiation."@en }
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- Q161238 abstract "Magnetic resonance imaging (MRI), nuclear magnetic resonance imaging (NMRI), or magnetic resonance tomography (MRT) is a medical imaging technique used in radiology to image the anatomy and the physiological processes of the body in both health and disease. MRI scanners use strong magnetic fields, radio waves, and field gradients to form images of the body.Many atomic nuclei have a property called "spin", which is associated with a magnetic dipole moment (analogous to a compass needle). All hydrogen atoms have nuclear spin, and are thus detectable by MRI. Water, having molecular formula H2O, contains a vast number of hydrogen atoms. The human body is roughly 70-percent water by mass, and most MRI scans essentially measure the spatial distribution of water in the object being imaged. The large tube into which the subject is placed is surrounded by a superconducting solenoid that produces a strong magnetic field down the length of the bore. This magnetic field aligns the nuclear spins and generates an energy difference between spins aligned with or against the field. At any feasible field strength (typical values are 1.5 or 3.0 tesla), the energy difference is in the radio frequency range of the electromagnetic spectrum. To generate an image, pulses of radio-frequency energy are emitted by antennas that excite the nuclear spin energy transition. As the spins return to equilibrium (i.e. "relax"), they emit radio-waves with a frequency dependent on the strength of the magnetic field. This RF emission is very faint (on the order of 10−12 watts), and is received by antennas close to the anatomy being imaged. By creating a precise and known gradient in the main magnetic field (with additional RF coils), nuclei at different positions will have different frequencies. The Fourier transform can then be computed, extracting the contribution of these many different frequencies from the signal. A particular frequency corresponds to the signal from water at a particular location (voxel) and an image can be reconstructed. While the hydrogen protons of water are the most often imaged nuclei, phosphorus, sodium, and carbon are sometimes used in specialty applications. There is also a wide variety of techniques that can be used while still measuring the hydrogen nuclei, including diffusion weighted MRI (DWI), contrast enhanced MRI (DCE-MRI), and functional MRI (fMRI).MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to ionizing radiation.".