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Magnetic Resonance Imaging

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Magnetic resonance imaging is a medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body in both health and disease.

Medical imaging is the technique and process of creating visual representations of the interior of a body for clinical analysis and medical intervention, as well as visual representation of the function of some organs or tissues.

In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency.

An atom is the smallest constituent unit of ordinary matter that has the properties of a chemical element.

Magnetic Resonance Imaging (MRI) by AK LECTURES

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MRI scanners use strong magnetic fields, radio waves, and field gradients to generate images of the organs in the body.

In atomic, molecular, and solid-state physics, the electric field gradient measures the rate of change of the electric field at an atomic nucleus generated by the electronic charge distribution and the other nuclei.

Radio waves are a type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light.

A magnetic field is the magnetic effect of electric currents and magnetic materials.

Magnetic Resonance Imaging Explained by ominhs

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MRI does not involve x-rays, which distinguishes it from computed tomography.

A CT scan makes use of computer-processed combinations of many X-ray images taken from different angles to produce cross-sectional images of specific areas of a scanned object, allowing the user to see inside the object without cutting.

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While the hazards of x-rays are now well-controlled in most medical contexts, MRI can still be seen as superior to CT in this regard.

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MRI can often yield different diagnostic information compared with CT.

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There can be risks and discomfort associated with MRI scans.

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Compared with CT, MRI scans typically take far more time, are louder, and usually require that the subject go into a narrow, confined tube.

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In addition, people with some medical implants or other non-removable metal inside the body may be unable to safely undergo an MRI examination.

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MRI is based upon the science of nuclear magnetic resonance.

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Certain atomic nuclei can absorb and emit radio frequency energy when placed in an external magnetic field.

Radio frequency is any of the electromagnetic wave frequencies that lie in the range extending from around 7003300000000000000♠3 kHz to 7011300000000000000♠300 GHz, which include those frequencies used for communications or radar signals.

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In clinical and research MRI, hydrogen atoms are most-often used to generate a detectable radio-frequency signal that is received by antennas in close proximity to the anatomy being examined.

Hydrogen is a chemical element with chemical symbol H and atomic number 1.

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Hydrogen atoms exist naturally in people and other biological organisms in abundance, particularly in water and fat.

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For this reason, most MRI scans essentially map the location of water and fat in the body.

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Pulses of radio waves excite the nuclear spin energy transition, and magnetic field gradients localize the signal in space.

In quantum mechanics and particle physics, spin is an intrinsic form of angular momentum carried by elementary particles, composite particles, and atomic nuclei.

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By varying the parameters of the pulse sequence, different contrasts can be generated between tissues based on the relaxation properties of the hydrogen atoms therein.

In Fourier transform NMR spectroscopy and imaging, a pulse sequence describes a series of radio frequency pulses applied to the sample, such that the free induction decay is related to the characteristic frequencies of the desired signals.

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Since its early development in the 1970s and 1980s, MRI has proven to be a highly versatile imaging technique.

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While MRI is most prominently used in diagnostic medicine and biomedical research, it can also be used to form images of non-living objects.

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MRI scans are capable of producing a variety of chemical and physical data, in addition to detailed spatial images.

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MRI is widely used in hospitals and clinics for medical diagnosis, staging of disease and follow-up without exposing the body to ionizing radiation.

Ionising radiation is radiation that carries enough energy to free electrons from atoms or molecules, thereby ionizing them.

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