Ultra-weak photon emission during ischemia-reperfusion: Characterizing response dynamics and reproducibility.

Topical formulation containing natural oligomeric proanthocyanidins (OPCS) reduces UV-induced oxidative stress in skin as assessed by ultra-weak photon emission (UPE)

A new aspect covering interactions between cells and their surroundings via electromagnetic waves was introduced by applying ultra-weak photon emission (UPE). The UPE originates from the relaxation of electronically excited species resulting from oxidative metabolic processes and oxidative stress associated with reactive oxygen species (ROS). The ROS plays a critical role in the quality of foods, and their determination is of extreme importance. The ROS and the intensity of the UPE have significantly correlated. The UPE can be effectively monitored by specific instruments such as photomultiplier tube and charged-coupled devices. The current review is devoted to providing an overview of the quality of food products by the aid of UPE via evaluating the correlations between UPE and food quality indices. In this regard, the UPE can be utilized in food quality as a real-time, noninvasive, and nondestructive technique without complex instruments. However, the implementation of the UPE method for evaluation of food quality needs further investigations.

The aim of the present study was to test whether the multifractal properties of ultra-weak photon emission (UPE) from germinating wheat seedlings (Triticum aestivum) change when the seedlings are treated with different concentrations of the toxin potassium dichromate (PD). To this end, UPE was measured (50 seedlings in one Petri dish, duration: approx. 16.6- 28 h) from samples of three groups: (i) control (group C, N = 9), (ii) treated with 25 ppm of PD (group G25, N = 32), and (iii) treated with 150 ppm of PD (group G150, N = 23). For the multifractal analysis, the following steps where performed: (i) each UPE time series was trimmed to a final length of 1000 min; (ii) each UPE time series was filtered, linear detrended and normalized; (iii) the multifractal spectrum (f(α)) was calculated for every UPE time series using the backward multifractal detrended moving average (MFDMA) method; (iv) each multifractal spectrum was characterized by calculating the mode (αmode) of the spectrum and the degree of multifractality (Δα); (v) for every UPE time series its mean, skewness and kurtosis were also calculated; finally (vi) all obtained parameters where analyzed to determine their ability to differentiate between the three groups. This was based on Fisher's discriminant ratio (FDR), which was calculated for each parameter combination. Additionally, a non-parametric test was used to test whether the parameter values are significantly different or not. The analysis showed that when comparing all the three groups, FDR had the highest values for the multifractal parameters (αmode, Δα). Furthermore, the differences in these parameters between the groups were statistically significant (p < 0.05). The classical parameters (mean, skewness and kurtosis) had lower FDR values than the multifractal parameters in all cases and showed no significant difference between the groups (except for the skewness between group C and G150). In conclusion, multifractal analysis enables changes in UPE time series to be detected even when they are hidden for normal linear signal analysis methods. The analysis of changes in the multifractal properties might be a basis to design a classification system enabling the intoxication of cell cultures to be quantified based on UPE measurements.

The human skin is usually exposed to ultraviolet A (UVA) in the sunlight and experiences oxidative stress associated with skin disorders and aging. Although oxidative stress caused by UVA exposure is assumed to be dependent on skin colour, few studies have demonstrated this dependency. We investigated the effects of skin colour on UVA-induced oxidative stress using ultraweak photon emission (UPE) generated from the skin during oxidation processes. The UPE intensities of skin samples were detected using a photomultiplier tube every second without any labelling. We irradiated skin tissue of different colours with UVA and measured UPE over time. UVA-induced UPE could be detected from immediately after irradiation to 2h after irradiation, indicating persistent oxidative stress. Skin lightness (L*) positively correlates with UPE intensity. Lighter-coloured skin exhibited more UVA-induced UPE, indicating higher oxidative stress. Additionally, oxidative stress persisted significantly more in lighter skin compared with darker skin. Skin tissues exhibited pigment darkening after UVA irradiation. Our results suggest that skin lightness affects oxidative stress induced by UV irradiation. Our study demonstrated the relationship between skin lightness and UVA-induced oxidative stress for the first time and offers new photodermatological insights into the human skin.

Diffusion tensor imaging (DTI) is very useful for investigating white matter integrity in ageing and neurological disorders; thus, evaluating its reproducibility under different acquisition protocols and analysis methods may assist in the design of clinical studies. To measure the reproducibility of DTI in normal subjects, this study include (1) depicting the reproducibility of DTI measurements in commonly used regions-of-interest analysis by intraclass correlation coefficient (ICC) and coefficient of variation (CV), (2) evaluating and comparing inter and intrasession test-retest reproducibility, and (3) illustrating the effect of the number of diffusion-encoding directions (NDED) and registration algorithms on measurement reproducibility. DTI measurements exhibit high reproducibility, with overall (430/480) ICC ≥ 0.70, (478/480) within-subject CV (CVws) ≤10.00 % and between-subject CV (CVbs) ranging from 1.32 to 13.63 %. Repeated measures ANOVAs and paired t tests were conducted to compare inter and intrasession reproducibility with different diffusion sampling schemes and registration algorithms. Our results also confirmed that increasing the NDED could improve the accuracy and reproducibility of DTI measurements. In addition, we compared reproducibility indices that were derived using different registration algorithms, and a tensor-based deformable registration yielded the most reproducible results. Finally, we found that increasing the NDED could reduce the difference between the reproducibility of measurement derived using different registration algorithms and between the reproducibility of intersession and intrasession. Our results suggest that the choice of DTI acquisition protocol and post-processing methods can influence the accurate estimation and reproducibility of DTI measurements and should be considered carefully for clinical applications.

Purpose To evaluate the intraobserver repeatability and interobserver reproducibility of Strip Meniscometry Tube (SMTube) and determine the correlations among the SMTube measurements and other ocular examinations in dry eye disease (DED) patients. Methods The study recruited 73 eyes of 49 DED patients. Every subject was subjected to the following five measurements sequentially: the Ocular Surface Disease Index (OSDI) questionnaire, Tear Meniscus Height (TMH) assessment, SMTube measurements, tear film breakup time (BUT) examination, and Schirmer I test (SIT). The repeatability and reproducibility of the measurements were assessed by the intraclass correlation coefficient (ICC) and the Bland–Altman analysis, and the correlations were evaluated by the Spearman rank-order correlation. Results The repeatability and reproducibility of the SMTube measurements were good in DED patients. The ICCs between the repeatability and reproducibility of the SMTube measurements were 0.789 and 0.741, respectively, and the Bland–Altman 95% limits of the repeatability and the reproducibility were −1.726 to 1.658 and −0.967 to 1.474, respectively (all P < 0.01). The SMTube measurements had correlations with TMH, BUT, and SIT. The Spearman rank correlation coefficients between SMTube and TMH; SMTube and Schirmer I test; and SMTube and BUT were 0.632, 0.617, and 0.653, respectively (all P < 0.01). Conclusions The measurements of the SMTube may provide a novel, swift, noninvasive, and convenient approach to screen and diagnose DED with acceptable repeatability and reproducibility and specific correlations with TMH, BUT, and SIT.

Optical coherence tomography angiography (OCTA) has been widely applied into children, however, few studies have assessed the repeatability and reproducibility of papillary and peripapillary VD in healthy children. To assess the precision of papillary and peripapillary vascular density (VD) measurements using optical coherence tomography angiography (OCTA) and analyze the effects of the signal strength index (SSI) and axial length (AL) on precision estimates. This was a prospective observational study. Seventy-eight children aged 6-16 years underwent 4.5 × 4.5 mm OCTA (RTVue XR Avanti) disc scans: two scans by one examiner (repeatability) and two additional scans by another examiner (reproducibility). Within-subject standard deviation (Sw), test-retest reproducibility (TRT), within-subject coefficient of variation (CoV), intraclass correlation coefficient (ICC), and Bland-Altman analysis were performed. In repeatability measurement, the fluctuation ranges (minimum to maximum) of VD between intraexaminer A/B in Sw, TRT, CoV, and ICC were (1.05-2.17)% / (1.16-2.32)%, (2.9-6)% / (3.21-6.44)%, (1.9-4.47)% / (2.08-5)%, and (0.588-0.783)% / (0.633-0.803)%, respectively. In reproducibility measurement, the fluctuation ranges of VD in Sw, TRT, CoV, and ICC were 1.11-2.13%, 3.07-5.91%, 1.99-4.41%, and 0.644-0.777%, respectively. VD was negatively correlated with SSI in most sectors of the peripapillary (e.g., inferior nasal, temporal inferior, temporal superior, superior temporal, and superior nasal). AL was positively correlated with inferior temporal VD and negatively correlated with superior nasal VD. Optical coherence tomography angiography showed moderate-to-good repeatability and reproducibility for papillary and peripapillary perfusion measurements in healthy children. The SSI value affects most of the peripapillary VD, while AL affects only the temporal inferior and nasal superior peripapillary VD.

Inter-Scan Reproducibility of Carotid Plaque Volume Measurements by 3-D Ultrasound

Quantitative diffusion-weighted imaging (DWI) MRI is a promising technique for cancer characterization and treatment monitoring. Knowledge of the reproducibility of DWI metrics in breast tumors is necessary to apply DWI as a clinical biomarker. To evaluate the repeatability and reproducibility of breast tumor apparent diffusion coefficient (ADC) in a multi-institution clinical trial setting, using standardized DWI protocols and quality assurance (QA) procedures. Prospective. In all, 89 women from nine institutions undergoing neoadjuvant chemotherapy for invasive breast cancer. DWI was acquired before and after patient repositioning using a four b-value, single-shot echo-planar sequence at 1.5T or 3.0T. A QA procedure by trained operators assessed artifacts, fat suppression, and signal-to-noise ratio, and determine study analyzability. Mean tumor ADC was measured via manual segmentation of the multislice tumor region referencing DWI and contrast-enhanced images. Twenty cases were evaluated multiple times to assess intra- and interoperator variability. Segmentation similarity was assessed via the Sørenson-Dice similarity coefficient. Repeatability and reproducibility were evaluated using within-subject coefficient of variation (wCV), intraclass correlation coefficient (ICC), agreement index (AI), and repeatability coefficient (RC). Correlations were measured by Pearson's correlation coefficients. In all, 71 cases (80%) passed QA evaluation: 44 at 1.5T, 27 at 3.0T; 60 pretreatment, 11 after 3 weeks of taxane-based treatment. ADC repeatability was excellent: wCV = 4.8% (95% confidence interval [CI] 4.0, 5.7%), ICC = 0.97 (95% CI 0.95, 0.98), AI = 0.83 (95% CI 0.76, 0.87), and RC = 0.16 * 10-3 mm2 /sec (95% CI 0.13, 0.19). The results were similar across field strengths and timepoint subgroups. Reproducibility was excellent: interreader ICC = 0.92 (95% CI 0.80, 0.97) and intrareader ICC = 0.91 (95% CI 0.78, 0.96). Breast tumor ADC can be measured with excellent repeatability and reproducibility in a multi-institution setting using a standardized protocol and QA procedure. Improvements to DWI image quality could reduce loss of data in clinical trials. 2 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2019;49:1617-1628.

Fixel-based analysis (FBA) has gained substantial interest for its ability to probe fibre-specific changes in the brain’s white matter from diffusion-weighted imaging data. However, the reproducibility and reliability of fixel-based measures across different scanners remains largely unknown. In this work, we present TRAMFIX (TRavelling Across Melbourne for FIXel-based analysis): a multisite dataset of traveling participants (n = 10 healthy adults) scanned across four 3T MRI scanners using a harmonised multi-shell diffusion-weighted imaging (DWI) protocol. DWI data were processed using two pipelines that can be adopted when performing multi-site FBA studies (site-specific vs. pooled processing). We extracted fixel-based measures of fibre density (FD), fibre cross-section (FC), and fibre density and cross-section (FDC) from the harmonized protocol. While the primary goal was to assess reproducibility and reliability of FBA metrics, we additionally computed diffusion tensor imaging (DTI)-based fractional anisotropy (FA) and mean diffusivity (MD) for the purposes of comparison with previous studies. Within-subject coefficients of variation (CVws) and intraclass correlation coefficients (ICC) of FBA and DTI measures were computed at multiple resolutions of computation and analysis: (i) the whole-brain averaged level, (ii) tract-level, and (iii) fixel- or voxel-level. Fixel-based metrics demonstrated high reproducibility and reliability at the whole-brain level (CVws ranging between 0.51% to 1.57% and ICC between 0.782 and 0.994). While reproducibility and reliability remained high for tract-averaged FBA measures (particularly the FC and FDC metrics), some tracts exhibited lower ICC values < 0.8 for the FD measure. When examining fixel-level reliability and reproducibility, clear spatial patterns emerged, with lower ICC across subcortical and cerebellar regions, and higher CVws at the cortical boundaries. FBA metrics demonstrated comparable, if not slightly better, reliability than tensor-based metrics derived from a subset of the same data. Our findings provide support for the reproducibility and reliability of fixel-based measures, highlighting their potential for use in multi-site FBA studies. Future work examining protocol-related differences, as well as appropriate harmonization strategies when pooling data across sites and scanners, will be valuable. To facilitate this, we provide the TRAMFIX dataset as a resource for investigating reproducibility, reliability, and harmonization of fixel-based analysis measures.

PET-based radiomic metrics are increasingly utilized as predictive image biomarkers. However, the repeatability of radiomic features on PET has not been assessed in a test-retest setting. The prostate-specific membrane antigen-targeted compound 18 F-DCFPyL is a high-affinity, high-contrast PET agent that we utilized in a test-retest cohort of men with metastatic prostate cancer (PC). Data of 21 patients enrolled in a prospective clinical trial with histologically proven PC underwent two 18 F-DCFPyL PET scans within 7 days, using identical acquisition and reconstruction parameters. Sites of disease were segmented and a set of 29 different radiomic parameters were assessed on both scans. We determined repeatability of quantification by using Pearson's correlations, within-subject coefficient of variation (wCOV), and Bland-Altman analysis. In total, 230 lesions (177 bone, 38 lymph nodes, 15 others) were assessed on both scans. For all investigated radiomic features, a broad range of inter-scan correlation was found (r, 0.07-0.95), with acceptable reproducibility for entropy and homogeneity (wCOV, 16.0% and 12.7%, respectively). On Bland-Altman analysis, no systematic increase or decrease between the scans was observed for either parameter (±1.96 SD: 1.07/-1.30, 0.23/-0.18, respectively). The remaining 27 tested radiomic metrics, however, achieved unacceptable high wCOV (≥21.7%). Many common radiomic features derived from a test-retest PET study had poor repeatability. Only Entropy and homogeneity achieved good repeatability, supporting the notion that those image biomarkers may be incorporated in future clinical trials. Those radiomic features based on high frequency aspects of images appear to lack the repeatability on PET to justify further study.

Interobserver reproducibility of maximal axial diameter and tumour volume measurements from CT of patients with head and neck squamous cell carcinoma

Improved reproducibility in scanning capacitance microscopy for quantitative 2D carrier profiling on silicon

To determine the reproducibility of optical coherence tomography/scanning laser ophthalmoscope (OCT/SLO) measurements within and between observers and within and between sessions in healthy eyes. Forty eyes of 40 healthy volunteers recruited from the outpatient service of the Department of Ophthalmology at the University Hospital of Alexandroupolis, Greece, were included. Retinal thickness scans were performed 3 times by two experienced operators within each of 3 sessions, which took place within a month, using the spectral OCT/SLO. The OCT/SLO provides retinal nerve fiber layer (RNFL) thickness and volume measurements and a 3D tomography analysis of optic nerve head. Statistical analysis was conducted using Bland-Altman plots, coefficient of variation (CoV), and intraclass correlation coefficient (ICC). As shown by the CoV values, RNFL parameters were generally found to have high reproducibility (CoV ranging from 4.3% to 10.9% for both operators), whereas optic disc parameters had scores reaching up to 22.5%. On the other hand, as shown by the ICC values, intraobserver and interobserver reproducibility for the OCT/SLO was high for optic disc parameters but low for RNFL thickness and volume measurements. Interobserver reproducibility was found to be highest for the maximum cup depth parameter and lowest for the superior volume. Bland-Altman plots indicate that bias is minimal for practically all parameters and scatterplot homoscedasticity is high. According to our data, SLO/OCT generally has a good reproducibility profile, as differences between the two operators were small. However, additional studies on the reproducibility of measurements with the OCT/SLO are needed.

Reproducibility of direct quantitative measures of cortical bone microarchitecture of the distal radius and tibia by HR-pQCT