Development of a magnetic-resonance-compatible photoplethysmograph amplifier for behavioral and emotional studies.

The purpose of the present study was to develop a magnetic resonance (MR) compatible photoplethysmograph (PPG) system that can measure the raw PPG signal during MR image acquisition. The system consists of an optic sensor that measures the optic signal, an optic cable that transmits a near-infrared optic signal, a signal amplifier, and a filter for noise removal. To minimize interactive noise, only the optic cable and the optic sensor module are located inside the MR room; the signal amplifier and filter are located outside the MR room. An experiment verified that a reliable PPG signal can be obtained without causing a deterioration in the MR image.