The continuous-wave Near-infrared spectroscopy (NIRS) devices have been highlighted for its clinical and health care applications in noninvasive hemodynamic measurements. The baseline shift of the deviation measurement attracts lots of attentions for its clinical importance. Nonetheless current published methods have low reliability or high variability. In this study, we found a perfect polynomial fitting function for baseline removal, using NIRS. Unlike previous studies on baseline correction for near-infrared spectroscopy evaluation of non-hemodynamic particles, we focused on baseline fitting and corresponding correction method for NIRS and found that the polynomial fitting function at 4th order is greater than the function at 2nd order reported in previous research. Through experimental tests of hemodynamic parameters of the solid phantom, we compared the fitting effect between the 4th order polynomial and the 2nd order polynomial, by recording and analyzing the R values and the SSE (the sum of squares due to error) values. The R values of the 4th order polynomial function fitting are all higher than 0.99, which are significantly higher than the corresponding ones of 2nd order, while the SSE values of the 4th order are significantly smaller than the corresponding ones of the 2nd order. By using the high-reliable and low-variable 4th order polynomial fitting function, we are able to remove the baseline online to obtain more accurate NIRS measurements.
Brain death is defined as permanent loss of the brain functions. The evaluation of it has many meanings, such as the relief of organ transplantation stress and family burden. However, it is hard to be judged precisely. The standard clinical tests are expensive, time consuming and even dangerous, and some auxiliary methods have limitations. Functional near infrared spectroscopy (fNIRS), monitoring cerebral hemodynamic responses noninvasively, evaluate brain death in some papers published, but there is no discussion about which experimental mode can monitor brain death patient more sensitively. Here, we attempt to use our fNIRS to evaluate brain death and find which experimental mode is effective. In order to discuss the problem, we detected eleven brain death patients and twenty normal patients under natural state. They were provided different fraction of inspiration O2 (FIO2) in different phase. We found that the ratio of ∆[HbO2] (the concentration changes in oxyhemoglobin) to ∆[Hb] (the concentration changes in deoxyhemoglobin) in brain death patients is significantly higher than normal patients in FIO2 experiment. Combined with the data analysis result, restore oxygen change process and low-high-low paradigm is more sensitively.
KEYWORDS: Photons, Head, Tissue optics, Absorption, Monte Carlo methods, Near infrared spectroscopy, Brain activation, Sensors, 3D modeling, Data modeling
Near infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) has been used to measure brain activation, which are clinically important. Monte Carlo simulation has been applied to the near infrared light propagation model in biological tissue, and has the function of predicting diffusion and brain activation. However, previous studies have rarely considered hair and hair follicles as a contributing factor. Here, we attempt to use MCVM (Monte Carlo simulation based on 3D voxelized media) to examine light transmission, absorption, fluence, spatial sensitivity distribution (SSD) and brain activation judgement in the presence or absence of the hair follicles. The data in this study is a series of high-resolution cryosectional color photograph of a standing Chinse male adult. We found that the number of photons transmitted under the scalp decreases dramatically and the photons exported to detector is also decreasing, as the density of hair follicles increases. If there is no hair follicle, the above data increase and has the maximum value. Meanwhile, the light distribution and brain activation have a stable change along with the change of hair follicles density. The findings indicated hair follicles make influence of NIRS in light distribution and brain activation judgement.
Deep vein thrombosis (DVT), happening in inpatients usually and especially with the postoperative population, is a serious disease characterized by an increased incidence. The venography is the golden standard to diagnose DVT. However, it involves invasive contrast agent injection and give patients physical and mental pressure. Functional nearinfrared spectroscopy (fNIRS) has been reported recently to diagnose DVT. Thrombolytic therapy activates the dissolution system with an exogenous activator that dissolves coronary thrombosis. The vena cava filter is a medical filter used for the treatment of thrombosis and the prevention of pulmonary embolism. Here we attempt to use portable NIRS for the DVT monitoring in the whole process of vena cava filter implantation and thrombolytic treatment, and contrast the patients of untreated, vena cava filter implantation and thrombolytic treatment. 19 DVT patients and 12 normal subjects were recruited. Thereinto, 7 patients have taken vena cava filter implantation, and 6 patients have taken the thrombolytic treatment. It was found that deoxyhemoglobins (Δ[Hb]) fluctuates and even increases in DVT. After vena cava filter implantation, Δ[Hb] increases first, then decreases. However, it emerges the rising trend and converge to the curves of normal subjects in thrombolytic treatment. The oxyhemoglobins (Δ[HbO2]) emerges opposite trend in most paradigms. The findings reveal the potential of fNIRS for monitoring DVT and therapeutic effect evaluation of thrombolysis and vena cava filters.
Acupuncture has a long history of more than 2000 years in China. However, traditional acupuncture adopts metallic needles which may bring discomfort and pricking to patients. Laser acupuncture (LA) is a non-invasive and painless way to achieve some therapeutic effects. And compared to traditional acupuncture, LA is free from infection. Taking these advantages of LA into consideration, we innovatively developed a portable laser acupuncture device with therapy part and detection part together. Therapy part sends out laser at the wavelength of 650 nm onto special acupoints of patients. And detection part includes integrated light-emitting diode (LED, 735/805/850 nm) and photodiode (OPT101). The detection part is used for the data collection for calculation of hemodynamic parameters based on near-infrared spectroscopy (NIRS). In this work, we carried out current-power test for sensitivity of therapy part. And we also conducted liquid-model optical experiment and arm blocking test for the sensitivity and effectiveness of detection part. The final results demonstrated great potential and reliability of the novel laser acupuncture device. In the future, we will apply this device in clinical applications to verify the effectiveness of the device and improve the reliability for more treatment of diseases.
KEYWORDS: Monte Carlo methods, Head, Low level phototherapy, Brain, Animal model studies, Light emitting diodes, In vivo imaging, Clinical trials, 3D displays, Absorption, 3D modeling, Tissues, Laser therapeutics, Blood
Stroke is a devastating disease, which is the third leading cause of death and disability worldwide. Although the incidence of stroke increases progressively with age, morbidity among young and middle-aged adults is increasing annually. Medications nevertheless remain the bulwarks of stroke. The treatment is ineffective, speculative and has a long treatment cycle. The function of acupuncture and moxibustion, which are potential therapeutic tools for stroke, is still controversial. Recently, Low-level light therapy (LLLT) has been demonstrated potent in vivo efficacy for treatment of ischemic conditions of acute myocardial infraction and stroke in multiple validated animal models. Optimum LLLT treatment has a dominant influence on therapy of stroke. While more than a thousand clinical trials have been halted, only a few trials on animals have been reported. We addressed this issue by simulating near-infrared light propagation with accurate visible Chinese human head by Monte Carlo modeling. The visible human head embody region of atherosclerotic plaques in head. Through comparing the light propagation of different light illumination, we can get a precise, optimized and straightforward treatment. Here, we developed a LLLT helmet for treating stroke depend on near-infrared light. There are more than 30 LED arrays in in multi-layered 3D printed helmet. Each LED array has independent water-cooling module and can be adjusted to touch the head of different subjects based on Electro pneumatic module. Moreover, the software provides the setup of illumination parameters and 3D distribution of light fluence rate distribution in human brain.
Laser acupuncture is an effective photochemical and nonthermal stimulation of traditional acupuncture points with lowintensity
laser irradiation, which is advantageous in painless, sterile, and safe compared to traditional acupuncture. Laser
diode (LD) provides single wavelength and relatively-higher power light for phototherapy. The quantitative effect of
illumination parameters of LD in use of laser acupuncture is crucial for practical operation of laser acupuncture.
However, this issue is not fully demonstrated, especially since experimental methodologies with animals or human are
pretty hard to address to this issue. For example, in order to protect viability of cells and tissue, and get better therapeutic
effect, it’s necessary to control the output power varied at 5mW~10mW range, while the optimized power is still not
clear. This study aimed to quantitatively optimize the laser output power, wavelength, and irradiation direction with
highly realistic modeling of light transport in acupunctured tissue. A Monte Carlo Simulation software for 3D vowelized
media and the highest-precision human anatomical model Visible Chinese Human (VCH) were employed. Our 3D
simulation results showed that longer wavelength/higher illumination power, larger absorption in laser acupuncture; the
vertical direction emission of the acupuncture laser results in higher amount of light absorption in both the acupunctured
voxel of tissue and muscle layer. Our 3D light distribution of laser acupuncture within VCH tissue model is potential to
be used in optimization and real time guidance in clinical manipulation of laser acupuncture.
Brain death, the irreversible and permanent loss of the brain and brainstem functions, is hard to be judged precisely for some clinical reasons. The traditional diagnostic methods are time consuming, expensive and some are even dangerous. Functional near infrared spectroscopy (FNIRS), using the good scattering properties of major component of blood to NIR, is capable of noninvasive monitoring cerebral hemodynamic responses. Here, we attempt to use portable FNIRS under patients’ natural state for brain death diagnosis. Ten brain death patients and seven normal subjects participated in FNIRS measurements. All of them were provided different fractional concentration of inspired oxygen (FIO2) in different time periods. We found that the concentration variation of deoxyhemoglobin concentration (Δ[Hb]) presents the trend of decrease in the both brain death patients and normal subjects with the raise of the FIO2, however, the data in the normal subjects is more significant. And the concentration variation of oxyhemoglobins concentration (Δ[HbO2]) emerges the opposite trends. Thus Δ[HbO2]/Δ[Hb] in brain death patients is significantly higher than normal subjects, and emerges the rising trend as time went on. The findings indicated the potential of FNIRS-measured hemodynamic index in diagnosing brain death.
Deep vein thrombosis (DVT) is of serious mortality and morbidity, which often happens in inpatients and especially with the postoperative population [1]. The golden standard to diagnose DVT is venography, which relies on complicated imaging modalities requiring to be injected in a vein below the clot invasively and ionizing procedures that employing xray imaging to show where and how the DVT blocks. The near-infrared spectroscopy (NIRS) is recently found to be an intriguing and potential method detecting DVT in clinics. It has been reported recently that employing NIRS to diagnose DVT. Arteriosclerosis obliterans (ASO), local extremities manifestations of systemic atherosclerosis, usually cause thrombosis and the reduction of distal blood flow. Thrombolytic therapy is to use exogenous activator to activate the dissolution system, which can dissolve intracoronary thrombus. Here we attempt to monitor the DVT and ASO patients during the whole procedure of thrombolytic treatment, then compare the data with those DVT and ASO patients did not take treatments and normal population. 8 DVT and 9 ASO patients and 12 normal subjects were recruited to take the measurements of concentration variation of oxy- and deoxy-hemoglobins (Δ[HbO2] and Δ[Hb]) by NIRS-based thrombosis monitor. Thereinto, 5 DVT and 6 ASO patients has taken the thrombolytic treatment, and the data for the periods before treatment, during treatment, and after treatment were extracted for analysis. We found that Δ[HbO2] fluctuates and even decreases in DVT and ASO patients. After the thrombolytic therapy, Δ[HbO2] increases about 45% and converge to the curves of normal subjects. And the Δ[Hb] emerges the similar trends, except for the rising trend in the beginning and the downtrend after thrombolytic therapy. The findings indicated NIRS has big potential in clinical monitoring of DVT and ASO patients and offering reliable and quantitative evaluation of thrombolytic therapy outcomes.
Fatigue driving is one of the leading roles to induce traffic accident and injury, which urgently desires a novel technique
to monitor the fatigue level at driving. Functional near infrared spectroscopy (fNIRS) is capable of noninvasive
monitoring brain-activities-related hemodynamic responses. Here, we developed a fINRS imager and setup a classic
psychological experiment to trigger visual divided attention which varied responding to driving fatigue, and attempted to
record the drive-fatigue-level correlated hemodynamic response in the prefrontal cortex. 7 volunteers were recruited to
take 7 hours driving and the experimental test was repeated every 1 hour and 8 times in total. The hemodynamic
response were extracted and graphed with pseudo image. The analysis on the relationship between the fNIRS-measured
hemodynamic response and fatigue level finally displayed that the oxyhemoglobin concentration in one channel of left
prefrontal lobe increased with driving duration in significant correlation. And the spatial pattern of hemodynamic
response in the prefrontal lobe varied with driving duration as well. The findings indicated the potential of fNIRSmeasured
hemodynamic index in some sensitive spot of prefrontal lobe as a driving fatigue indicator and the promising
use of fNIRS in traffic safety field.
This article introduces a novel method to estimate oxygen saturation of the internal jugular vein blood (SjvO2) by using Near Infrared spectroscopy (NIRS). The different positions of patients can affect the cross-sectional area (CSA) of the internal jugular vein (IJV), in other words, it causes the sectional change of the IJV blood volume. When lying position of patients, the CSA is larger than that keeping upper body 80 degree, and the CSA can compute quantitatively by the use of ultrasound and digital image processing methods. The entire method consist of constructing different position of patient (upper body rotation 0 and 80 degree), comparing the light absorption changes. SjvO2 has been determined from light absorption measurements in two wavelength, before and after the position changes. The method has been applied to the vertical area over the IJV of 11 patients who were placed a central venous catheter into a large vein in the neck for medical uses, using wavelength of 735 and 850 nm. At last, comparing the SjvO2NIRS which measured by NIRS noninvasively with SjvO2IJVBG which was quantified using a whole blood gas analyzer, we found there were some certain relativity. The results were influenced by vascular depth greatly.
Clinical shock-monitoring mainly depends on measuring oxygen saturations from SVC blood samples invasively. The golden standard indicator is the central internal jugular vein oxygenation (SjvO2). Using near-infrared spectroscopy (NIRS) also can monitor shock in some papers published, but there is no discussion about which oxygen saturation (cerebral venous oxygen saturation, ScvO2; tissue oxygen saturation of internal jugular area; tissue oxygen saturation of extremities areas) can monitor shock patient more sensitively and accurately. The purpose of this paper is to examine which one is most effective. In order to discuss the problem, we continuously detected 56 critical patients who may be into shock state using NIRS oximeter at prefrontal, internal jugular vein area and forearm, and chose 24 patients who were into shock and then out of shock from the 56 critical patients. Combined with the patients’ condition, the pulse oxygen saturation is most sensitively to monitoring shock than the others, and the internal jugular vein area oxygen saturation is most effective.
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