magnetic resonance imaging

(noun)

Commonly referred to as MRI; a technique that uses nuclear magnetic resonance to form cross sectional images of the human body for diagnostic purposes.

Related Terms

Examples of magnetic resonance imaging in the following topics:

  • NMR and MRIs

    • Magnetic resonance imaging is a medical imaging technique used in radiology to visualize internal structures of the body in detail.
    • Magnetic resonance imaging (MRI), also called nuclear magnetic resonance imaging (NMRI) or magnetic resonance tomography (MRT), is a medical imaging technique used in radiology to visualize internal structures of the body in detail.
    • MRI utilized the property of nuclear magnetic resonance (NMR) to image the nuclei of atoms inside the body.
    • This electromagnetic field has just the right frequency (known as the resonance frequency) to become absorbed and then reverse the rotation of the hydrogen protons in the magnetic field.
    • MRI shows a marked contrast between the different soft tissues of the body, making it especially useful in imaging the brain, the muscles, the heart, and cancerous tissue—as compared with other medical imaging techniques such as computed tomography (CT) or X-rays.

  • Biopsychology

    • Neuroimaging tools, such as functional magnetic resonance imaging (fMRI) scans, are often used to observe which areas of the brain are active during particular tasks in order to help psychologists understand the link between brain and behavior.
    • Magnetic resonance imaging (MRI) scans of the head are often used to help psychologists understand the links between brain and behavior.
    • Different brain-imaging techniques provide scientists with insight into different aspects of how the human brain functions.
    • Three types of scans include (left to right) PET scan (positron emission tomography), CT scan (computed tomography), and fMRI (functional magnetic resonance imaging).

  • Medical Imaging

    • Medical imaging is used to create images of the human body used for clinical purposes, diagnostic procedures or medical science.
    • This imaging modality utilizes a wide beam of x rays for image acquisition and is the first imaging technique available in modern medicine.
    • A magnetic resonance imaging instrument (MRI), or "nuclear magnetic resonance (NMR) imaging" scanner as it was originally known, uses powerful magnets to polarize and excite hydrogen nuclei (single proton) in water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body scanner .
    • This is the "resonance" part of MRI.
    • A magnetic resonance imaging instrument (MRI scanner), or "nuclear magnetic resonance (NMR) imaging" scanner as it was originally known, uses powerful magnets to polarize and excite hydrogen nuclei (single proton) in water molecules in human tissue, producing a detectable signal which is spatially encoded, resulting in images of the body.

  • Brain Imaging Techniques

    • Neuroimaging, or brain scanning, includes the use of various techniques to directly or indirectly image the structure, function, or pharmacology of the brain.
    • Magnetic resonance imaging (MRI) and functional magnetic resonance imaging (fMRI) scans are the form of neural imaging most directly useful to the field of psychology.
    • An MRI uses strong magnetic fields to align spinning atomic nuclei (usually hydrogen protons) within body tissues, then disturbs the axis of rotation of these nuclei and observes the radio frequency signal generated as the nuclei return to their baseline status.
    • Through this process, an MRI creates an image of the brain structure.
    • One disadvantage is that the patient has to hold still for long periods of time in a noisy, cramped space while the imaging is performed.

  • Emission Topography

    • Positron emission tomography is a nuclear medical imaging technique that produces a three-dimensional image of processes in the body.
    • Positron emission tomography (PET) is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the body.
    • PET scans are increasingly read alongside CT or magnetic resonance imaging (MRI) scans, with the combination giving both anatomic and metabolic information.
    • Because PET imaging is most useful in combination with anatomical imaging, such as CT, modern PET scanners are now available with integrated high-end multi-detector-row CT scanners .
    • Because the two scans can be performed in immediate sequence during the same session, with the patient not changing position between the two types of scans, the two sets of images are more-precisely registered, so that areas of abnormality on the PET imaging can be more perfectly correlated with anatomy on the CT images.

  • Basic Techniques in Protein Analysis

    • The crystal scatters the X-rays onto an electronic detector that is the same type used to capture images in a digital camera.
    • The result is a three-dimensional digital image of the molecule.
    • Another protein imaging technique, nuclear magnetic resonance (NMR), uses the magnetic properties of atoms to determine the three-dimensional structure of proteins.
    • This technique depends on the fact that certain atomic nuclei are intrinsically magnetic.

  • Proton NMR Spectroscopy

    • This important and well-established application of nuclear magnetic resonance will serve to illustrate some of the novel aspects of this method.
    • A solution of the sample in a uniform 5 mm glass tube is oriented between the poles of a powerful magnet, and is spun to average any magnetic field variations, as well as tube imperfections.
    • If the magnetic field is smoothly increased to 2.3488 T, the hydrogen nuclei of the water molecules will at some point absorb rf energy and a resonance signal will appear.
    • For visibility, the water proton signal displayed in the image below is much broader than it would be in an actual experiment.
    • Since protons all have the same magnetic moment, we might expect all hydrogen atoms to give resonance signals at the same field / frequency values.

  • Introduction

    • Over the past fifty years nuclear magnetic resonance spectroscopy, commonly referred to as nmr, has become the preeminent technique for determining the structure of organic compounds.
    • A spinning charge generates a magnetic field, as shown by the image below.
    • The resulting spin-magnet has a magnetic moment (μ) proportional to the spin.
    • Strong magnetic fields are necessary for nmr spectroscopy.
    • The international unit for magnetic flux is the tesla (T).

  • Paramagnetism and Diamagnetism

    • Paramagnetism is the attraction of material while in a magnetic field, and diamagnetism is the repulsion of magnetic fields.
    • Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field.
    • Paramagnetic materials have a relative magnetic permeability greater or equal to unity (i.e., a positive magnetic susceptibility) and hence are attracted to magnetic fields.
    • Unlike ferromagnets, paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because thermal motion randomizes the spin orientations responsible for magnetism.
    • Orientation in paramagnetic material when electric field is applied (right image) and removed (left image).

  • Solenoids, Current Loops, and Electromagnets

    • Solenoids are loops of wire around a metallic core, and can be used to create controlled magnetic fields.
    • Electromagnetism is the use of electric current to make magnets.
    • These temporarily induced magnets are called electromagnets.
    • Electromagnets are employed for many uses: from a wrecking yard crane that lifts scrapped cars, to controlling the beam of a 90-km-circumference particle accelerator, to the magnets in medical imaging machines (for other examples see ).
    • An electromagnet creates magnetism with an electric current.