Magnetocardiography (MCG) is a technique to measure the
magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
s produced by electrical activity in the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
using extremely sensitive devices such as the Superconducting Quantum Interference Device (
SQUIDSuperconducting Quantum Interference Devices are very sensitive magnetometers used to measure extremely small magnetic fields, based on superconducting loops containing Josephson junctions....
s). If the magnetic field is measured using a multichannel device, a map of the magnetic field is obtained over the chest; from such a map, using mathematical
algorithmIn mathematics, computing, linguistics, and related subjects, an algorithm is an effective method for solving a problem using a finite sequence of instructions. Algorithms are used for calculation, data processing, and many other fields....
s that take into account the conductivity structure of the
torsoTorso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. It is sometimes referred to as the trunk. The torso includes the thorax and abdomen.-Major organs:...
, it is possible to locate the source of the activity.
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Magnetocardiography (MCG) is a technique to measure the
magnetic fieldMagnetic fields surround magnetic materials and electric currents and are detected by the force they exert on other magnetic materials and moving electric charges...
s produced by electrical activity in the
heartThe heart is a muscular organ found in all vertebrates that is responsible for pumping blood throughout the blood vessels by repeated, rhythmic contractions...
using extremely sensitive devices such as the Superconducting Quantum Interference Device (
SQUIDSuperconducting Quantum Interference Devices are very sensitive magnetometers used to measure extremely small magnetic fields, based on superconducting loops containing Josephson junctions....
s). If the magnetic field is measured using a multichannel device, a map of the magnetic field is obtained over the chest; from such a map, using mathematical
algorithmIn mathematics, computing, linguistics, and related subjects, an algorithm is an effective method for solving a problem using a finite sequence of instructions. Algorithms are used for calculation, data processing, and many other fields....
s that take into account the conductivity structure of the
torsoTorso is an anatomical term for the central part of the many animal bodies from which extend the neck and limbs. It is sometimes referred to as the trunk. The torso includes the thorax and abdomen.-Major organs:...
, it is possible to locate the source of the activity. For example, sources of abnormal rhythms or arrhythmia, may be located using MCG.
History
The first MCG measurements were made by Baule and McFee using two large coils placed over the chest, connected in opposition to cancel out the relatively large magnetic background. Heart signals were indeed seen, but were very noisy. The next development was by David Cohen, who used a magnetically-shielded room to reduce the background, and a smaller coil with better electronics; the heart signals were now less noisy, allowing a magnetic map to be made, verifying the magnetic properties and source of the signal. However, the use of an inherently noisy coil detector discouraged widespread interest in the MCG. The turning point came with the development of the sensitive detector called the SQUID (superconducting quantum interference device) by James Zimmerman. The combination of this detector and Cohen's new shielded room at
MITThe Massachusetts Institute of Technology is a private research university located in Cambridge, Massachusetts. MIT has five schools and one college, containing a total of 32 academic departments, with a strong emphasis on scientific and technological research...
allowed the MCG signal to be seen as clearly as the conventional
electrocardiogramElectrocardiography is a transthoracic interpretation of the electrical activity of the heart over time captured and externally recorded by skin electrodes. It is a noninvasive recording produced by an electrocardiographic device...
, and the publication of this result marked the real beginning of magnetocardiography (as well as Biomagnetism generally).
Magnetocardiography is now used in various
laboratoriesA laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
and
clinicA clinic is a small private or public health facility that is devoted to the care of outpatients, often in a community, in contrast to larger hospitals, which also treat inpatients. Some grow to be institutions as large as major hospitals, whilst retaining the name clinic...
s around the world, both for research on the normal human heart, and for clinical
diagnosisDiagnosis is the identification of the nature of anything, either by process of elimination or other analytical methods...
.
See also
- Biomagnetism
Biomagnetism is the phenomenon of magnetic fields produced by living organisms; it is a subset of bioelectromagnetism. The study of the biological effects of magnetic fields is magnetobiology...
- Magnetic field imaging
Magnetic Field Imaging is a non-invasive and side-effect-free cardiac diagnostic method. It detects and records the electromagnetic signals that are associated with the heartbeat using a multi channel magnetic sensor array. The electric signals are known from the ECG and recordings of the magnatic...
- Magnetoencephalography
Magnetoencephalography is an imaging technique used to measure the magnetic fields produced by electrical activity in the brain via extremely sensitive devices such as superconducting quantum interference devices . These measurements are commonly used in both research and clinical settings...
- Magnetogastrography
Magnetogastrography is the science of recording magnetogastrograms . Magnetogastrograms are recordings of magnetic fields resulting from electrical activity from the stomach and can be considered similar to electrocardiograms. The magnetic fields are typically recorded using SQUIDs.-External links:*...
- David Cohen (physicist)
David Cohen is known mostly for his pioneering work in the area of Biomagnetism , where he made many of the first measurements....
- James Edward Zimmerman
James Edward Zimmerman was born in Lantry, South Dakota. He was a coinventor of the radio-frequency superconducting quantum interference device and he is credited with coining the term.- Career :...
External links
- http://www.biomag.hus.fi/mcg.html
- http://www.biomag2006.ca
- http://www.biomag2008.org/