TDK and Yokohama National University (YNU) have developed an image diagnosis technology based on a high-sensitivity magnetic sensor that detects weak magnetic fields at room temperature. Its magnetic field detection performance almost reaches that of the superconducting quantum interference device (SQUID) flux meter, which requires cooling.
The prototype technology is related to the magnetic particle imaging method intended to detect and create images of magnetic particles accumulated in a tumour or blood vessel.
Magnetic resonance imaging (MRI) diagnostics and X-ray computerised tomography (CT) scanning are used in clinical services in the diagnosis of organ health, tumours and other conditions, using the contrasting density of imaged objects. In comparison, the magnetic particle imaging is intended for use in detecting only the tracers in the imaged objects to create images similar to positron-emission tomography (PET) and similar technologies.
The principle of the magnetic particle imaging is to detect the magnetic signals generated by magnetic particles accumulated in a tumour or blood vessel from outside of the body (see figure). When intended for use in medical imaging, it is important for devices to be highly sensitive to enable the detection of small amounts of magnetic particles. Though magnetic particle imaging technologies primarily use a method that measures electromotive force electromagnetically induced through detection coils, the new technology developed by YNU utilises a prototype high-sensitivity magnetic sensor to achieve this. The prototype high-sensitivity magnetic sensor was developed by TDK for use in the detection weak magnetic fields at room temperature. Although still under development, the prototype sensor has been shown in a prior feasibility study to measure magnetic field distribution in a heart. Through this development, the sensor has successfully reduced the strength of the alternate current magnetic fields applied from outside of the body to one tenth lower than conventional levels. This reduced strength of the applied field is achieved by the non-linear response characteristics of the sensor to the measured magnetic field strength. Now it is expected that using high-sensitivity magnetic sensors will enable magnetic particles to be detected across wider body, including the head.
The next step for the team is to develop the practical imaging device for clinical use.