Magnetic field imaging
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Magnetic Field Imaging (MFI) is a new and non-invasive cardiac diagnostic tool which supplies a functional image of the whole heart at every instant. It records, displays and analyzes the changes in the magnetic field, generated by the heart during all phases of the heartbeat.
The general principal is based on two facts:
- Cell activity in the human body is connected to electric activity (based on Galvani, Italy 1780).
- Electric current is associated with a corresponding magnetic field (based on Ørsted, Denmark 1820).
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 signal travels through the body almost without disturbance and is recorded contact free. Furthermore, the magnetic signals of so called vortex currents, which occur regularly in every heartbeat and do include important information for an advanced and more accurate cardiac diagnosis, can be measured with an MFI system, but can not be recorded electrically on the body surface. (Vortex currents within the cardiac muscle, J. Wikswo, 1982).
Magnetic field changes measured in the human body by means of MFI are about one million times weaker than the magnetic field of the earth. High end acquisition electronics and noise reduction concepts are necessary. BMDSys uses the most sensitive magnetic sensors presently available, Superconducting Quantum Interference Devices (SQUID), which are cooled down to 4 K (-269 °C) with liquid helium. This temperature allows using quantum effects to detect the magnetic fields with a sensitivity very near to the theoretical limits.
MFI is an absolutely non-invasive, radiation free, purely passive recording system gathering information from the electrical activity of the heart cells. MFI does not need any external magnetic field, no other external energy sources to be absorbed or reflected by the patient and no contrast agents are necessary. The measurement is contact-free.
Indications
The main fields of use today are the risk stratification of ventricular tachycardia (VT) and the detection of stress induced ischemia. The MFI system can detect the onset of arrhythmic and ischemic diseases in a very early stage with high accuracy for both acute and asymptomatic patients.
- Early Detection: Arrhythmia; Ischemia; Angina pectoris; Cardiac microvascular diseases
- Direct diagnosis of heart function after myocardial infarction (MI) and surgery of heart transplantation
- On-going Monitoring of patients with heart surgical intervention: Patients with a stent or who underwent a balloon dilatation; Post bypass patients; Post heart trans-plantation patients
As MFI is absolutely risk free and harmless for the patient, the procedure can be repeated without any negative effects for the patient, which gives the cardiologist the opportunity to observe a patient's progressive changes. The non-invasiveness of MFI makes it an ideal tool for the diagnosis of pregnant women as well as it can in addition detect the cardiac signal of an unborn child starting from the 4th month of pregnancy.
Clinical routine application
MFI is now available for clinical routine use with high impact applications in cardiology. The data acquisition is fast (two minutes for a rest MFI) and the analysis result is available in less than a minute after the examination. Even in the case of complex data analysis, results are available within a few minutes. The special data acquisition and patient handling software makes the procedure very easy for the nurse performing it. Depending on the indication, the data can be displayed and analyzed in various modalities which allow the medical doctors to look at the patient’s heartbeat in slow motion, being able to exactly observe even the smallest functional abnormalities. Based on reliable data, medical doctors can make decisions for appropriate treatment in appropriate time.
