Towards real-time non contact spatial resolved oxygenation monitoring using a multi spectral filter array camera in various light conditions

Abstract

Non contact spatial resolved oxygenation measurements remain an open challenge in the biomedical field and non contact patient monitoring. Although point measurements are the clinical standard till this day, regional differences in the oxygenation will improve the quality and safety of care. Recent developments in spectral imaging resulted in spectral filter array cameras (SFA). These provide the means to acquire spatial spectral videos in real-time and allow a spatial approach to spectroscopy. In this study, the performance of a 25 channel near infrared SFA camera was studied to obtain spatial oxygenation maps of hands during an occlusion of the left upper arm in 7 healthy volunteers. For comparison a clinical oxygenation monitoring system, INVOS, was used as a reference. In case of the NIRS SFA camera, oxygenation curves were derived from 2-3 wavelength bands with a custom made fast analysis software using a basic algorithm. Dynamic oxygenation changes were determined with the NIR SFA camera and INVOS system at different regional locations of the occluded versus non-occluded hands and showed to be in good agreement. To increase the signal to noise ratio, algorithm and image acquisition were optimised. The measurement were robust to different illumination conditions with NIR light sources. This study shows that imaging of relative oxygenation changes over larger body areas is potentially possible in real time.

A Spectral Filter Array Camera for Clinical Monitoring and Diagnosis: Proof of Concept for Skin Oxygenation Imaging

“…Table 1. Overview of spectral imaging techniques including RGB [33], filter wheel cameras (FW), liquid crystal tunable filter (LCTF) cameras, spectroscopy [34] (Spec), spatial frequency domain imaging (SFDI) [31,[35][36][37], multispectral illumination (MI) [1,38], SFA spectral filter array [39]. SFA implementations provide a good tradeoff between true simultaneous snapshot capture of all wavelength, higher number of spectral bands, medium costs, ease of use and acquisition speed in terms of frames per seconds (fps).…”

“…In order to measure the oxygenation of burn-wounds a near infrared model of the camera might be necessary. Previous work [39] has shown that the proposed method for oxygen estimation can be applied to the near infrared version of the camera.…”

An Evaluation Framework for Spectral Filter Array Cameras to Optimize Skin Diagnosis

“…SFA cameras could combine non-contact monitoring of vital functions and diagnosis of diseased skin tissue in real time [21,22,23,24,25,26,27,28]. In particular, dynamic processes such as oxygenation would highly benefit from spectral and spatially resolved images in real time [27,29,30,31,32].…”