PPG100C-MRI front panel controls allow selection of either absolute or relative plethysmographic measurements. Signal processors are able to distinguish between physiological signal and MRI artifact as manifested by gradient switching during MRI sequences, such as Shim or EPI.
Because MRI-related transient artifact is removed at the source, the MRI version amplifier can be sampled at the same rate as during normal (non-MRI) physiological recording. There is no longer any requirement to over-sample the amplifier output to capture every nuance of MRI artifact to train secondary computer-based processing steps to remove such artifact.
Use with the TSD200-MRI transducer (matched infrared emitter and photo diode detector), which transmits changes in infrared reflectance resulting from varying blood flow. Blood is highly reflective of near infrared light wavelengths, due to the heme subunit of hemoglobin. When the PPG transducer is placed on the skin, in proximity to capillaries, the reflectance of the infrared light from the emitter to the detector will change in accordance to capillary blood volume. The PPG waveform peaks when capillary blood volume is maximized.
IMPORTANT! See Safety Guidelines for recording biopotential measurements in the MRI environment.