Design and Development of an MRI Compatible Circuit Suitable for Pre-Clinical Physiological Monitoring in a 4.7T Magnetic Resonance Imaging

Abstract

As monitoring preclinical MRI is essential, it is important that the equipment used must be MRI-compatible. This is because interaction with an MRI radiofrequency (RF) transmitting field can cause RF burns due to inappropriate equipment. And non-compatible MRI monitoring equipment can give inaccurate readings in the MRI system if the equipment has ferromagnetic components. Preclinical MRI is designed for animals, the model used to study diseases related to humans. Animal models are imaged using a smaller scanner with high magnetic fields like the 4.7T. The main parameters of interest are the respiratory rate, the temperature, the pressure transducer and the electrocardiogram (ECG), this is because the animal model is used as a laboratory experiment for human disease. An MRI-compatible lead Ⅱ ECG simulator, with approximately 0.5 mV output amplitude was attached to the input of the ECG preamplifier to represent a small animal’s signal. The transmitted signal is the ECG, the pressure sensor, the temperature, and the battery (voltage), these are all linked to different channels (outside, near and inside magnet) and were acquired with the pressure sensor pad taped on a male adult volunteer’s thumb to record the human pulse of 70 bpm, which is similar to the respiration rate of an anaesthetized mouse or rat. The use of a signal gating generator should be explored in future work, this could make the monitoring parameters to be independent of the RF pulse influence. Finally, fibre optics should be included in the design process.