Temperature measurement in soft tissue using a distributed fibre Bragg-grating sensor system.

Currently used temperature sensor systems do not provide sufficient spatial resolution and can not be used as an integrated part of minimally invasive treatment. Few magnetic resonance (MR) compatible sensor systems are available. A distributed fibre Bragg-grating sensor system for use in biological tissue was constructed. Ten Bragg gratings were inscribed in the core of an optical fibre. The fibre was mounted into tubes made of MR-compatible materials. An opto-electronic unit connected to the fibre was used for signal generation and detection. Communication with a PC allowed presentation and logging of temperature data. The system was calibrated to the temperature range –195.8°C to 100°C. Experiments were conducted during freezing (cryoablation) of porcine liver in vivo . The system yielded a temperature profile with 6.5 mm spatial resolution and 5 s temporal resolution. Both mechanical stability and MR compatibility were acceptable and will allow routine use.