Objective To design a new method of determining optical properties of biological tissue by measuring light intensity distribution.Methods The light distribution in Intralipid-10％ suspension at 650 nm was measured by optical fiber probe.The optical parameters were derived from nonlinear regression of the diffusion equation for intensity.The distribution and anisotropy of intensity was abtained by the determined optical parameters and the diffusion equation for intensity.ResultsThis new method was feasible by comparing the experimental data with published results.ConclusionThe experiment results would provide useful information for radiative transfer equation,marine optical remote sensing measurement and laser therapeutic applications.-

Objective In order to further improve the noninvasive measurement precision of human blood glucose and achieve clinical requirements,experiments were conducted to measure human blood glucose by a novel measurement method our group proposed.Methods The blood flow of the tested parts was stopped by pressure,and dynamic distribution of transmission spectra was measured by time-correlated single-photon counting (TCSPC) technology under the dual wavelength light incident.Oral glucose tolerance test (OGTT) was conducted on three human subjects,and the early arriving photons were selected by Laplace transform.Meanwhile,the human blood glucose concentration was measured using the Roche glucose meter.Results The best curve fitting was got when the Laplace parameter was 1Gs-1 (determining parameter R2=0.0922).Conclusions The experimental results showed that better measurement accuracy can be obtained by selecting appropriate Laplace parameter,and noninvasive measurement of human blood glucose under flow control of time gate was feasible.

Objective To theoretically study the non-invasive measurement method of blood hemoglobin in vivo based on the time-resolved approach combined with occlusion spectroscopy.Methods The dynamic dual wavelength time-resolved transmission was analyzed based on the artificial blood flow kinetics condition on a human finger model.The sensitivity of hemoglobin measurement was improved by Laplace transforming of time-domain data.The method was validated using hemoglobin with a mass concentration range of 6～16 g/dl.Results The simulation results showed that compared with the continuous wave method,the time-resolved method could provide higher detection sensitivity using Laplace transform parameter p =5 × 1010 s-1.Conclusions The sensitivity of hemoglobin measurement can be enhanced when early arriving photons are emphasized by Laplace transformingthe time-resolved transmission with a small positive parameter.

A novel near-infrared (NIR) diffuse correlation spectroscopy (DCS) has recently been developed for noninvasive monitoring of tumor blood flow during photodynamic therapy (PDT).DCS offers several attractive new features for tumor blood flow measurement such as noninvasiveness,portability,low cost,high temporal resolution and relatively large penetration depth.DCS technology has been utilized for continuous measurement of tumor blood flow before,during and after PDT in both animals and humans.The ultimate goal is to predict treatment outcomes from the measured tumor hemodynamic responses to PDT.

Objective To conduct breath test with a relatively large number of subjects for new data regarding breath acetone in diabetes using a high accuracy and high data throughput breath acetone analyzer based on the cavity ringdown spectroscopy (CRDS) technique.Methods The CRDS breath analyzer was validated by standard acetone gas samples with various concentrations and golden standard gas chromatography-mass spectrometry (GC-MS).A total of 917 breath samples from 260 type 2 diabetic (T2D) patients and 30 healthy individuals were collected under each of 4 different conditions: fasting, 2 h post-breakfast, 2 h post-lunch, and 2 h post-dinner, and the samples were tested by the breath analyzer.Results The linear fitting curve of standard acetone samples with various concentration had good linearity (R=1, P＜0.05).The linear fitting of the results of GC-MS and CRDS was 0.98, suggesting that the obtained acetone concentrations using both methods were consistent.For the 260 T2D subjects, the exhaled breath acetone concentrations ranged from 0.0 to 10.6×10-6, while for the 30 healthy subjects, the breath acetone concentration ranged from 0.1 × 10-6 to 2.0× 10-6.The mean breath acetone concentration of the 260 T2D subjects was (1.5±1.l)× 10-6, which was 1.4 times of(1.1±0.5)×10-6 for the 30 healthy subjects.The mean breath acetone concentrations under the 4 conditions for the 260 T2D subjects ((1.6±1.2)×10-6, (1.4±1.0)×10-6~, (1.4±0.9)×10-6, and (1.4±1.2)× 10-6) were higher than that of the 30 healthy subjects ((1.3±0.3)×10-6, (1.0±0.6)×10-6, (1.0±0.6)×10-6, and (1.1±0.4)×10-6), respectively.No correlation was found between the breath acetone concentration and the blood glucose level of the T2D subjects and the healthy individuals.Conclusions The GC-MS validation confirms that the CRDS breath acetone analyzer is a reliable instrument for fast response and on-line breath acetone measurement.An elevated mean breath acetone concentration exists in T2D subjects.The relationship between breath acetone level and physiological parameters needs to be further investigated.

Objective To study the concentration distribution of acetone in fasting exhaled breath in diabetic patients and healthy subjects,to explore the effect of individual indexes on the concentration of acetone in fasting exhaled breath,and to study the role of individual indexes of fasting exhaled breath acetone in diabetes screening.Methods The acetone concentration measurements of fasting exhaled breath were performed on 265 healthy subjects,39 patients with type 1 diabetes (T1D),and 300 patients with type 2 diabetes (T2D) using real-time online respiratory acetone analyzer based on cavity ring-down spectroscopy (CRDS).SPSS 19.0 software was used to eliminate outliers,and relevant statistical analysis was carried out with the corresponding gender,age,height,body mass,body mass index (BMI) and blood glucose concentration (BGL).The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic value of fasting breath acetone concentration for diabetes diagnosing.Results The mean fasting breath acetone concentration in T1D patients was (2.24±1.43)×10-6 was significantly higher than (1.43±0.55)×10-6 in healthy subjects and (1.41±0.73)×10-6 in T2D patients,and the differences were statistically significant (all P＜0.05).The average fasting breath acetone concentration in male diabetic patients was higher than that in female patients.The mean fasting breath acetone concentration was positively correlated with age (R=0.31,P＜0.01) in healthy subjects,was positively correlated with BMI (R=0.33,P＜0.05) in T1D patients,and was positively correlated with height (R=0.18,P＜0.01) in T2D patients.The area under the ROC curve for the diagnosis of T1D by fasting breath acetone concentration was 0.853 with a sensitivity of 71.9％ and specificity of 87.4％ (P＜0.01),and for the diagnosis of T2D was 0.528 with a sensitivity of 54.1％ and specificity of 55.0％ (P＞0.05).Conclusions The detection of fasting breath acetone concentration is meaningful for T1D diagnosing,but has a low accuracy for T2D diagnosing (no statistically significant).

Human exhaled gases contain thousands of trace amounts of trace volatile organic compounds (VOCs), some of which are endogenous substance and can be detected as potential biomarkers for disease. Acetone, the second highest VOCs in human exhaled gases, has been widely used in non-invasive diagnosis and monitoring of diabetes. At present, more than 30 independent studies have been undertaken on the range of breath acetone concentration and its influencing factors, and the quantitative relationship between blood glucose and glycosylated hemoglobin in diabetic patients. However, there are still many challenges in the application of breath acetone as a clinical regulatory parameter for diabetes. In this paper, the research status and progress in the breath acetone and analysis method were reviewed, and the existing problems in diabetes diagnosis and monitoring were discussed. Besides, the future development prospects were analyzed with the present technical level.