Abstract
In the field of biomedicine, there are optical systems that provide the tissue metabolic rate of oxygen consumption (tMRO2) by the simultaneous measurement of blood flow and oxygenation level. However, current optical systems are costly and require complex optical alignments, which are inconvenient for clinical applications. Therefore, in this study, we developed a simple diffuse optical metabolic spectroscopy system by combining a broadband light source and a laser and by sharing a spectrometer as a detector for both diffuse optical spectroscopy and diffuse speckle contrast analysis. This system simultaneously measures blood flow, volume, and oxygenation in a simple and cost-effective manner. The system response to flow is demonstrated through the flow phantom experiments. The results of the experiments show that flow response is in the range 0~0.9 ml/min, with a resolution better than 0.1 ml/min. During the blood phantom study, the blood volume fraction increased linearly with blood accumulation. Further, the change in oxygenation was monitored with the modulation of the oxygen level in the gas supply. Finally, tMRO2 changes were measured during ischemia, induced by the upper arm cuff and the results showed a decrease and a recovery of tMRO2 with cuff inflation and deflation, respectively. This simple diffuse optical metabolic spectroscopic system can easily be applied in medical environments by providing a simple and convenient solution for measuring tMRO2.
Highlights
Over the last few decades, the diffuse optical techniques have been widely adopted in the biomedical field and demonstrates significant impact on the diagnosis of the stroke [1], cancer [2,3,4,5], and erectile dysfunction [6]
In this study, we proposed a development of diffuse optical metabolic spectroscopy based on diffuse optical spectroscopy (DOS) and DSCA combined system to calculate tissue metabolic rate of oxygen consumption by the simultaneous measurement of the blood flow, blood volume, and the oxygenation level in simple and costeffective manner
The results show an increase in 1/Kt2 from 615 to 9,314 corresponding to the flow rate, which increased from 0 ml/min to 0.9 ml/min
Summary
Over the last few decades, the diffuse optical techniques have been widely adopted in the biomedical field and demonstrates significant impact on the diagnosis of the stroke [1], cancer [2,3,4,5], and erectile dysfunction [6]. The basic function of diffuse optical systems is to either provide a blood flow information by monitoring speckle pattern alternations using coherent light [7] or provide blood volume and oxygenation level by measuring the attenuation of light intensity passing through the tissue at multi-wavelengths [8]. The advanced diffuse optical system that simultaneously records the speckle pattern alternations and lights attenuations at multi-wavelength by tissue, such as DW-LSCI [13,14], DCS-NIRS [15], DSCA-NIRS [16], LSI-SFDI [17], and PPG-LSCI [18] (DW-LSCI: dual-wavelength laser speckle contrast imaging, DCS: diffuse correlation spectroscopy, NIRS: near-infrared spectroscopy, DSCA: diffuse speckle contrast analysis, LSI: laser speckle imaging, SFDI: spatial frequency domain imaging, PPG: photo-plethysmography and LSCI: Laser speckle contrast imaging) have been developed to concurrently measure the blood flow and the oxygenation
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