Vital sign monitoring: a practical solution by a MR-compatible phonocardiography interferometric probe

Abstract

This paper deals with the description of S-1-S-1 interval detection of the phonocardiographic signal obtained by a fiber-optic Mach-Zehnder interferometer. A non-invasive measuring probe encapsulated in a bicomponent (base and catalyst) entitled Zhermack ZA 50 LT was designed. The probe is immune to the electromagnetic interferences (EMI) and therefore can be operated under strong magnetic fields. The laboratory results (obtained from 8 volunteers) were compared to the reference electrocardiograph (ECG) signal and evaluated by an objective Bland-Altman (B-A) method. Based on the results, it is possible to say that the S-1-S-1 interval detection with the presented fiber-optic interferometric probe is as reliable as the measurement of time between the R-R wave of the ECG signal since the B-A analysis resulted in 95.59 % samples laid in +/- 1.96 SD. The test carried out in a real Magnetic Resonance Imaging (MRI) environment demonstrated that the presence of the probe in the MRI scanner does not affect the quality of this imaging modality. The developed sensor can be suitable for cardiac triggering.