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Magnetic Field Imaging (MFI) 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 magnetic signals are also known from Magnetocardiography (MCG). In comparison to MCG, MFI, among others, always records the whole relevant area above the chest of the person, is focused on clinical routine application and supplies convenient and easy to use parameters for the clinician based on images. ==Background== The general principal of MFI is based on two facts: * Cell activity in the human body is connected to electric activity (based on Galvani, Italy 1786). * Electric current is associated with a corresponding magnetic field (based on Ørsted, Denmark 1819). The difference between the electric and the magnetic signals: In comparison to the electric signals, which are influenced by the differently conductive tissue of the body and varying resistance of the skin before they can be recorded, the magnetic signals travel through the body almost without disturbance. The differences in the electric potentials, that are recorded by the ECG, are directly depending on the inhomogeneity and geometry of the thorax, the magnetic signals outside of the thorax depend primarily on the intracellular currents of the cardiac tissue and only secondarily on the secondary currents generating the electric signal. Furthermore, the magnetic signals of so-called vortex currents, which occur regularly in every heartbeat and include important information for an advanced and more accurate cardiac diagnosis (first theoretically described by John Wikswo),〔Wikswo, J.P., Barach, J.P. "Possible sources of new information in the magnetocardiogram" in ''J. Theoret. Biol.'' Vol. 95 pp. 721 - 729, 1982〕〔Roth, B.J., Wikswo, J.P. "Electrically silent magnetic fields" in ''Biophys. J.'' Vol. 50 pp. 739 - 745, 1986〕 can be acquired with an MFI system, but cannot be recorded electrically on the body surface (First experimental hint by Brockmeier et al. 1994〔Brockmeier, K., Chomani, S., Erné, S.N. "Magnetocardiography and exercise test" in ''J. Electrocardiol.'' Vol. 27 pp. 137 - 142, 1994〕 and comprehensive demonstration Brockmeier et al. 1997).〔Brockmeier, K. et al "Magnetocardiography and 32 lead potential mapping: Repolarisation in normal subjects during pharmacologically induced stress" in ''J. Cardiovasc. Electrophysiol.'' Vol. 8 pp. 615 - 625, 1997〕 Recording technology The magnetic field changes detected by the MFI are about one million times weaker than the magnetic field of the earth. High end acquisition electronics and noise reduction concepts are necessary. As sensors the most sensitive magnetic sensors presently available, Superconducting Quantum Interference Devices (SQUID), which are cooled down to 4 K (-269 °C) with liquid helium, are used to acquire the signals. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Magnetic field imaging」の詳細全文を読む スポンサード リンク
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