Biexponential Model Research Articles

Improved thermal shock and oxidation resistance of β-SiAlON incorporated with h-BN

β-SiAlON ceramics incorporated with h-BN were prepared by gel casting combined with reaction bonding procedure. With the h-BN addition varying from 0 to 20 wt%, the bending strength was degraded from 102.5 MPa to 60.0 MPa. Compared to monolithic β-SiAlON, β-SiAlON/h-BNs have significantly better thermal shock resistance. At high temperature in air atmosphere, mass gain curves of both β-SiAlON and β-SiAlON/h-BN exhibited platform stage after certain oxidation time. Higher temperature benefits formation of protective layer which inhibited oxygen diffusion, then the oxidation of the samples was stagnated. Addition of h-BN make it easier to form the protective layer. Furthermore, B2O3 from oxidation of h-BN could inhibit the crystalizing of the glassy phase, hence, more stable protective layer could form stagnating oxidation process. Addition of h-BN in β-SiAlON exhibited excellent enhancement on thermal shock resistance and oxidation resistance, which is of vital importance for application in high temperature environments. An empirical biexponential model was suggested for describing the oxidation behavior of the ceramic material containing open pores prepared in this work.

New Insights into the Spread of MRS-Based Water T2 Values Observed in Highly Fatty Replaced Muscles.

The reference standard for assessing water T2 (T2,H2O ) at high fat fraction (FF) is 1 H MRS. T2,H2O (T2,H2O,MRS ) dependence on FF (FFMRS ) has recently been demonstrated in muscle at high FF (i.e. ≥60%). To investigate the relationship between T2,H2O,MRS and FFMRS in the thigh/leg muscles of patients with neuromuscular diseases and to compare with quantitative MRI. Retrospective case-control study. A total of 151 patients with neuromuscular disorders (mean age ± standard deviation = 52.5 ± 22.6 years, 54% male), 44 healthy volunteers (26.5 ± 13.0 years, 57% male). A 3-T; single-voxel stimulated echo acquisition mode (STEAM) MRS, multispin echo (MSE) imaging (for T2 mapping, T2,H2O,MRI ), three-point Dixon imaging (for FFMRI and mapping). Mono-exponential and bi-exponential models were fitted to water T2 decay curves to extract T2,H2O,MRS and FFMRS . Water resonance full-width-at-half-maximum (FWHM) and B0 spread (∆B0 ) values were calculated. T2,H2O,MRI (mean), FFMRI (mean, kurtosis, and skewness), and (mean) values were estimated in the MRS voxel. Mann-Whitney U tests, Kruskal-Wallis tests. A P-value <0.05 was considered statistically significant. Normal T2,H2O,MRS threshold was defined as the 90th percentile in healthy controls: 30.3 msec. T2,H2O,MRS was significantly higher in all patients with FFMRS < 60% compared to healthy controls. We discovered two subgroups in patients with FFMRS ≥ 60%: one with T2,H2O,MRS ≥ 30.3 msec and one with T2,H2O,MRS < 30.3 msec including abnormally low T2,H2O,MRS . The latter subgroup had significantly higher water resonance FWHM, ∆B0 , FFMRI kurtosis, and skewness values but nonsignificantly different (P = 1.00) and long T2,H2O,MRS component and its fraction (P > 0.11) based on the bi-exponential analysis. The findings suggest that the cause for (abnormally) T2,H2O,MRS at high FFMRS is biophysical, due to differences in susceptibility between muscle and fat (increased FWHM and ∆B0 ), rather than pathophysiological such as compartmentation changes, which would be reflected by the bi-exponential analysis. 3 TECHNICAL EFFICACY: Stage 3.

Synthesis and characterization of tris(5,7-diphenyl-8-quinolinolato) aluminum(III), gallium(III), and indium(III) complexes: Effect of metal ions on the structural, photoluminescence, thermal and electrochemical properties

The 5,7-diphenyl-8-hydroxyquinoline (5,7-Phq) organic ligand was successfully synthesized via Suzuki cross-coupling reaction followed by synthesis of the novel organometallic complexes tris(5,7-diphenyl-8-quinolinolato) metal(III) [M(5,7-Phq)3; M = Al, Ga, or In]. All synthesized M(5,7-Phq)3 complexes were characterized using various analytical techniques. The molecular structure of In(5,7-Phq)3 was confirmed using single-crystal X-ray crystallography, which indicates that the three 5,7-Phq ligands are arranged in a meridional configuration around the central metal In3+ ion, and the complex is distorted from ideal octahedral geometry. There are no significant differences in the UV–visible absorption spectra of the complexes in the tetrahydrofuran (THF) solution and they are all red-shifted compared to that of the parent Mq3 (M = Al3+, Ga3+, In3+) compounds. The broad absorption band at around 417 nm is assignable to the π-π* transition. The synthesized M(5,7-Phq)3 complexes in the solution and in the solid-state show red-shifted emission compared to that of the parent unsubstituted compounds. The decrease in the solution and the solid-state emission efficiency and intensity from Al to In complexes is attributed to the heavy atom effect. Despite the electrochemical band gap energies (Egec) of the complexes determined from cyclic voltammetry being in good agreement with those reported for the unsubstituted complexes, the optical band gap energies (Egopt) determined from the Tauc plot method are smaller. The results of the fluorescence decay of the M(5,7-Phq)3 complexes both in CHCl3 solution and in solid state at 298 K show that the decays fit a bi-exponential model with two lifetimes (τ1 and τ2). The average values of fluorescence lifetimes of the complexes in CHCl3 are significantly greater than those of the complexes in the solid state.

Utility of mono-exponential, bi-exponential, and stretched exponential signal models of intravoxel incoherent motion (IVIM) to predict prognosis and survival risk in laryngeal and hypopharyngeal squamous cell carcinoma (LHSCC) patients after chemoradiotherapy

PurposeTo investigate the predictive power of mono-exponential, bi-exponential, and stretched exponential signal models of intravoxel incoherent motion (IVIM) in prognosis and survival risk of laryngeal and hypopharyngeal squamous cell carcinoma (LHSCC) patients after chemoradiotherapy.Materials and methodsForty-five patients with laryngeal or hypopharyngeal squamous cell carcinoma were retrospectively enrolled. All patients had undergone pretreatment IVIM examination, subsequently, mean apparent diffusion coefficient (ADCmean), maximum ADC (ADCmax), minimum ADC (ADCmin) and ADCrange (ADCmax − ADCmean) by mono-exponential model, true diffusion coefficient (D), pseudo diffusion coefficient (D*), perfusion fraction (f) by bi-exponential model, distributed diffusion coefficient (DDC), and diffusion heterogeneity index (α) by stretched exponential model were measured. Survival data were collected for 5 years.ResultsThirty-one cases were in the treatment failure group and fourteen cases were in the local control group. Significantly lower ADCmean, ADCmax, ADCmin, D, f, and higher D* values were observed in the treatment failure group than in the local control group (p < 0.05). D* had the greatest AUC of 0.802, with sensitivity and specificity of 77.4 and 85.7% when D* was 38.85 × 10–3 mm2/s. Kaplan–Meier survival analysis showed that the curves of N stage, ADCmean, ADCmax, ADCmin, D, D*, f, DDC, and α values were significant. Multivariate Cox regression analysis showed ADCmean and D* were independently correlated with progression-free survival (PFS) (hazard ratio [HR] = 0.125, p = 0.001; HR = 1.008, p = 0.002, respectively).ConclusionThe pretreatment parameters of mono-exponential and bi-exponential models were significantly correlated with prognosis of LHSCC, ADCmean and D* values were independent factors for survival risk prediction.

Kinetics of the reaction between Moringa oleifera leaf extracts and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical

In this study, an antioxidant-rich extract was obtained by leaching Moringa oleifera leaves. The activity of the extract against the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical was measured by determining a second-order rate constant (k2). The reaction between the mixture of antioxidants in the extract and the DPPH was monitored by measuring the absorbance at 517 nm in 30-second intervals for a period of 600 s. The absorbance exhibited a rapid decay within the first 100 s, followed by a slower decay. The absorbance data were fitted to a bi-exponential model. The curve fitting showed a linear relationship between the initial concentration of antioxidants and the reaction rate with the coefficient of determination values greater than 0.9979. The k2 value was 0.0870 ± 0.0007 mg/mL.

Investigation of image-based lesion and kidney dosimetry protocols for 177Lu-PSMA-I&T therapy with and without a late SPECT/CT acquisition

Background177Lu-PSMA therapy has been successfully used to prolong the survival of patients with metastatic castration-resistant prostate cancer. Patient-specific dosimetry based on serial quantitative SPECT/CT imaging can support the understanding of dose–effect relationships. However, multiple SPECT/CT measurements can be challenging for patients, which motivates the investigation of efficient sampling schedules and their impact on dosimetry. In this study, different time samplings with respect to the number and timing of SPECT/CT acquisitions with and without a late measurement were investigated.Materials and methodsIn total, 43 lesions and 10 kidneys of 5 patients receiving 177Lu-PSMA-I&T therapy were investigated. Whole-body SPECT/CT measurements were performed at 1, 2, 3 and 7 days post-injection. For both lesions (isocontour-based segmentation) and kidneys (CT-based segmentation), a reference model was employed including all four time points. To identify the best-matching fit function out of a pre-defined set of models, visual inspection, coefficients of variation and sum of squared errors were considered as goodness-of-fit criteria. Biologically effective doses (BEDs) calculated with different time samplings (days 1, 2, 3/1, 2, 7/1, 3, 7/2, 3, 7 and 1, 2/1, 3/1, 7) were compared to the reference.ResultsThe best-fit function was found to be a mono-exponential model for lesions and a bi-exponential model with a population-based parameter and two free parameters for kidneys. The BEDs calculated with the time sampling 1, 3, 7 days showed the lowest deviations from the reference for lesions with 4 ± 5%. Without day 7, still 86% of all lesions showed deviations from the reference < 10%. The outlier deviations showed a positive correlation with the effective half-life of the respective lesions. For kidneys, including days 1, 2, 3 achieved the best results with 0 ± 1%. Generally, deviations for kidneys were found to be small for all time samplings (max. 13%).ConclusionsFor combined optimization of the SPECT/CT time sampling for kidney and lesion dosimetry during 177Lu-PSMA-I&T therapy, the sampling with days 1, 3, 7 showed the smallest deviation from the reference. Without a late acquisition, using the schedule with days 1, 2, 3 is likewise feasible.

Monoexponential, biexponential, stretched-exponential and kurtosis models of diffusion-weighted imaging in kidney assessment: comparison between patients with primary aldosteronism and healthy controls.

This study used various diffusion-weighted imaging (DWI) models (including monoexponential, biexponential, stretched-exponential and kurtosis models) in renal magnetic resonance imaging (MRI) to compare whether there were differences in each diffusion parameter between patients with primary aldosteronism (PA) and healthy volunteers. Twenty-two (female:male, 14:8; age, 48 ± 10years) patients with PA and 22 age- and sex-matched healthy controls (HCs) underwent MRI examinations of the kidneys. The independent-sample t test or the Mann‒Whitney U test was used to detect differences in the diffusion metrics of the kidneys between the two groups. Univariable and multivariable linear regression were applied to analyze the correlations between diffusion parameters and the clinical indicators. The mean diffusivity (MD, p < 0.001) and radial diffusivity (Dr, p < 0.001) values in the medulla were lower in the PA group than in the HC group. The medullary fractional anisotropy (FA, p < 0.001) was higher than that of HCs. The FA (p < 0.001) and axial diffusivity (Da, p < 0.001) values in the cortex were lower in the PA group. The cortical α (anomalous exponent term, p = 0.016) was higher in the PA patients than in the HCs. Linear regression analysis showed that log(plasma aldosterone concentration) and the estimated glomerular filtration rate (eGFR) were correlated with medullary FA. The stretched-exponential model (cortical α) and the kurtosis model (FA, MD and Dr in the medulla and FA and Da in the cortex) showed significant differences between PA patients and healthy volunteers and may have potential for noninvasive renal assessment in PA patients.

Radiation dose estimates based on Monte Carlo simulation for spiral breast computed tomography imaging in a large cohort of patients.

Spiral breast computed tomography (BCT) equipped with a photon-counting detector (PCD) is a new radiological modality allowing for the compression-free acquisition of high-resolution 3-D datasets of the breast. Optimized dose exposu04170/re setups according to breast size were previously proposed but could not effectively be applied in a clinical environment due to ambiguity in measuring breast size. This study aims to report the standard radiation dose values in a large cohort of patients examined with BCT, and to provide a mathematical model to estimate radiation dose based on morphological features of the breast. This retrospective study was conducted on 1657 BCT examinations acquired between 2018 and 2021 from 829 participants (57±10 years, all female). Applying a dedicated breast tissue segmentation algorithm and Monte Carlo (MC) simulation, mean absorbed dose (MAD), mean glandular dose (MGD), mean skin dose (MSD), maximum glandular dose (maxGD), and maximum skin dose (maxSD) were calculated and related to morphological features such as breast volume, effective diameter, breast length, skin volume, and glandularity. Effective dose (ED) was calculated by applying the corresponding beam and tissue weighting factors, 1Sv/Gy and 0.12 per breast. Relevant morphological features predicting dose values were identified based on the Spearman's rank correlation coefficient. Exponential or bi-exponential models predicting the dose values as a function of morphological features were fitted by using a non-linear least squares (LS) method. The models were validated by assessing R2 and residual standard error (RSE). The most relevant morphological features for radiation dose estimation were the breast volume (correlation coefficient: -0.8), diameter (-0.7), and length (-0.6). The glandularity presented a weak-positive correlation (0.4) with MGD and maxGD due to the inhomogeneous distribution of the glandularity and absorbed dose in the 3-D breast volume. The standard MGDs were calculated to be 7.3±0.7, 6.5±0.3, and 5.9±0.3 mGy, MADs to 7.6±0.8, 6.8±0.3, and 6.2±0.3 mGy, maxSDs to 19.9±1.6, 19.5±0.5, and 18.9±0.5 mGy, and EDs to 0.88±0.08, 0.78±0.04, and 0.72±0.04 mSv for small, medium, and large breasts with average breast lengths of 5.9±1.6, 8.7±1.3, and 12.2±2.0cm, respectively. The estimated glandularity - 23.1±16.9, 12.5±11.4, and 6.9±7.3% from small to large breasts. The mathematical models were able to estimate the MAD, MGD, MSD, and maxSD as a function of each morphological feature with only upto 0.5 mGy RSE. We presented the typical morphological features and standard dose values according to the breast size acquired from a large patient cohort. We established radiation dose estimation models allowing accurate estimation of dose values including MGD with an acceptable RSE based on each of the easily measured morphological features of the breast. Clinicians could use the breast length to operate as a dosimetric alert of the scanner prior to a BCT scan. Radiation exposure for BCT was lower than diagnostic mammography (MG) and cone-beam breast CT (BCT).

Whole-lesion histogram analysis of multiple diffusion metrics for differentiating lung cancer from inflammatory lesions.

Whole-lesion histogram analysis can provide comprehensive assessment of tissues by calculating additional quantitative metrics such as skewness and kurtosis; however, few studies have evaluated its value in the differential diagnosis of lung lesions. To compare the diagnostic performance of conventional diffusion-weighted imaging (DWI), intravoxel incoherent motion (IVIM) magnetic resonance imaging (MRI) and diffusion kurtosis imaging (DKI) in differentiating lung cancer from focal inflammatory lesions, based on whole-lesion volume histogram analysis. Fifty-nine patients with solitary pulmonary lesions underwent multiple b-values DWIs, which were then postprocessed using mono-exponential, bi-exponential and DKI models. Histogram parameters of the apparent diffusion coefficient (ADC), true diffusivity (D), pseudo-diffusion coefficient (D*), and perfusion fraction (f), apparent diffusional kurtosis (Kapp) and kurtosis-corrected diffusion coefficient (Dapp) were calculated and compared between the lung cancer and inflammatory lesion groups. Receiver operating characteristic (ROC) curves were constructed to evaluate the diagnostic performance. The ADCmean, ADCmedian, D mean and D median values of lung cancer were significantly lower than those of inflammatory lesions, while the ADCskewness, Kapp mean, Kapp median, Kapp SD, Kapp kurtosis and Dapp skewness values of lung cancer were significantly higher than those of inflammatory lesions (all p < 0.05). ADCskewness (p = 0.019) and D median (p = 0.031) were identified as independent predictors of lung cancer. D median showed the best performance for differentiating lung cancer from inflammatory lesions, with an area under the ROC curve of 0.777. Using a D median of 1.091 × 10-3 mm2/s as the optimal cut-off value, the sensitivity, specificity, positive predictive value and negative predictive value were 69.23%, 85.00%, 90.00% and 58.62%, respectively. Whole-lesion histogram analysis of DWI, IVIM and DKI parameters is a promising approach for differentiating lung cancer from inflammatory lesions, and D median shows the best performance in the differential diagnosis of solitary pulmonary lesions.

Characterization of organic release kinetics in particleboard using a dual model fitting methodology.

In modern society, people spend most of their time indoors engaging in their work and home life. However, indoor air pollution is a potential risk to health, and it is associated with many diseases. Wooden furniture, as the most popular indoor furniture used in modern times, is a major source of indoor air pollution, so it has become imperative to explore the composition and release kinetics characteristics of toxic and hazardous substances from wood-based panels. In this study, thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS) was used to detect the release of organic compounds from wood panels, and determine the release kinetics of the organic compounds dimethyl acetal, phenol, toluene and decanoic acid via bi-exponential and mass transfer models to provide a theoretical basis for targeted pollution prevention and control. In this project, a climate chamber method was used to conduct a 120 h continuous sampling of the release concentration of compounds from wood panels. The TD-GC-MS method was used to analyze the sampling tubes, and the concentration-time data were fitted to the bi-exponential and mass transfer models. The emission factor equation was obtained from the bi-exponential model. The critical physical parameters, such as the initial internal release concentration C0, internal diffusion rate Dm, and solid-phase/gas-phase partition coefficient K, were obtained from the mass transfer model. Finally, it was found that dimethyl acetal and toluene were easily and rapidly released into the air, while phenol and decanoic acid were slowly released into the ambient air. The two sets of release kinetics characteristics provide an essential theoretical basis for targeted pollution prevention and control, as well as a methodological path for studying the release kinetics of different toxic and hazardous substances.

Experimental Data and Modeling for the Adsorption/Desorption of Tetracycline and Diclofenac on the Agricultural Soils

The adsorption-desorption characteristics of tetracycline and diclofenac onto two different agricultural soils (S1 and S2) were investigated using the batch equilibrium method. The adsorption experiments were used to optimize the two variable parameters (contact time (5-120 min), initial pollutant concentration (5-300 mg/L)) on the adsorption of tetracycline and diclofenac. The adsorption kinetics for tetracycline and diclofenac onto soil are well described by a bi-exponential adsorption model characterized by fast and slow adsorption rates. Non-linear adsorption curves fitted well to the Langmuir, Freundlich and Temkin equations. The maximum adsorption capacity (qm) of tetracycline and diclofenac onto the soils S1 and S2 were calculated to be 55.90 mg/g, 41.92 mg/g, 26 mg/g and 6.42 mg/g, respectively. Kd, Koc, foc and qa values were calculated. The adsorption efficiency of tetracycline and diclofenac by the soils S1 and S2 was over 97%. The Kd parameters for the adsorption of tetracycline and diclofenac onto the soils S1 and S2 were found to be 3537 L/kg, 654 L/kg, 1669 L/kg and 3105 L/kg, respectively. The reversibility of the adsorption process was evaluated by desorption experiments using different concentrations of HDTMA and Triton-x surfactants. The desorption rates were higher for diclofenac than for tetracycline.

Non-invasive intravoxel incoherent motion MRI in prediction of histopathological response to neoadjuvant chemotherapy and survival outcome in osteosarcoma at the time of diagnosis

BackgroundEarly prediction of response to neoadjuvant chemotherapy (NACT) is important to aid personalized treatment in osteosarcoma. Diffusion-weighted Intravoxel Incoherent Motion (IVIM) MRI was used to evaluate the predictive value for response to NACT and survival outcome in osteosarcoma.MethodsTotal fifty-five patients with biopsy-proven osteosarcoma were recruited prospectively, among them 35 patients were further analysed. Patients underwent 3 cycles of NACT (Cisplatin + Doxorubicin) followed by surgery and response adapted adjuvant chemotherapy. Treatment outcomes were histopathological response to NACT (good-response ≥ 50% necrosis and poor-response < 50% necrosis) and survival outcome (event-free survival (EFS) and overall survival (OS)). IVIM MRI was acquired at 1.5T at baseline (t0), after 1-cycle (t1) and after 3-cycles (t2) of NACT. Quantitative IVIM parameters (D, D*, f & D*.f) were estimated using advanced state-of-the-art spatial penalty based IVIM analysis method bi-exponential model with total-variation penalty function (BETV) at 3 time-points and histogram analysis was performed.ResultsGood-responders: Poor-responders ratio was 13 (37%):22 (63%). EFS and OS were 31% and 69% with 16.27 and 25.9 months of median duration respectively. For predicting poor-response to NACT, IVIM parameters showed AUC = 0.87, Sensitivity = 86%, Specificity = 77% at t0, and AUC = 0.96, Sensitivity = 86%, Specificity = 100% at t1. Multivariate Cox regression analysis showed smaller tumour volume (HR = 1.002, p = 0.001) higher ADC-25th-percentile (HR = 0.047, p = 0.005) & D-Mean (HR = 0.1, p = 0.023) and lower D*-Mean (HR = 1.052, p = 0.039) were independent predictors of longer EFS (log-rank p-values: 0.054, 0.0034, 0.0017, 0.0019 respectively) and non-metastatic disease (HR = 4.33, p < 10–3), smaller tumour-volume (HR = 1.001, p = 0.042), lower D*-Mean (HR = 1.045, p = 0.056) and higher D*.f-skewness (HR = 0.544, p = 0.048) were independent predictors of longer OS (log-rank p-values: < 10–3, 0.07, < 10–3, 0.019 respectively).ConclusionIVIM parameters obtained with a 1.5T scanner along with novel BETV method and their histogram analysis indicating tumour heterogeneity were informative in characterizing NACT response and survival outcome in osteosarcoma.

Image downsampling expedited adaptive least-squares (IDEAL) fitting improves intravoxel incoherent motion (IVIM) analysis in the human kidney.

To improve the reliability of intravoxel incoherent motion (IVIM) model parameter estimation for the DWI in the kidney using a novel image downsampling expedited adaptive least-squares (IDEAL) approach. The robustness of IDEAL was investigated using simulated DW-MRI data corrupted with different levels of Rician noise. Subsequently, the performance of the proposed method was tested by fitting bi- and triexponential IVIM model to in vivo renal DWI data acquired on a clinical 3 Tesla MRI scanner and compared to conventional approaches (fixed D* and segmented fitting). The numerical simulations demonstrated that the IDEAL algorithm provides robust estimates of the IVIM parameters in the presence of noise (SNR of 20) as indicated by relatively low absolute percentage bias (maximal sMdPB <20%) and normalized RMSE (maximal RMSE <28%). The analysis of the in vivo data showed that the IDEAL-based IVIM parameter maps were less noisy and more visually appealing than those obtained using the fixed D* and segmented methods. Further, coefficients of variation for nearly all IVIM parameters were significantly reduced in cortex and medulla for IDEAL-based biexponential (coefficients of variation: 4%-50%) and triexponential (coefficients of variation: 7.5%-75%) IVIM modelling compared to the segmented (coefficients of variation: 4%-120%) and fixed D* (coefficients of variation: 17%-174%) methods, reflecting greater accuracy of this method. The proposed fitting algorithm yields more robust IVIM parameter estimates and is less susceptible to poor SNR than the conventional fitting approaches. Thus, the IDEAL approach has the potential to improve the reliability of renal DW-MRI analysis for clinical applications.

Study of bone marrow microstructure in healthy young adults using intravoxel incoherent motion diffusion-weighted MRI.

Bone marrow is one of the most important organs in the human body. The evaluation of bone marrow microstructure and gender-related cellular and capillary networks in healthy young adults can help to better understand the process of bone metabolism. Intravoxel incoherent motion (IVIM) provides both diffusion and perfusion quantifications without requiring intravenous contrast agent injection. In this prospective study, 60 healthy young age-matched volunteers (30 men and 30 women) underwent MRI scans at 1.5 T using multi-b-value diffusion-weighted imaging on sagittal planes covering the lumbar bone marrow. The apparent diffusion coefficient (ADC), true ADC (D), pseudo-ADC (D*), and perfusion fraction (f) were calculated from the diffusion-weighted images using the mono- and bi-exponential models. Lumbar cancellous bone (L2-L4) was selected as the region of interest. An independent t-test was used to detect significant differences in ADC values and IVIM parameters between men and women. The differences in IVIM parameters among the L2, L3, and L4 groups were compared with analysis of variance. The D and f values in women were significantly higher than that in men (p = 0.001, 0.026). However, D* was significantly lower in women than that in men (p = 0.001). Furthermore, there was no significant gender difference for the conventional ADC value (p = 0.186). Moreover, there were no significant differences in the D, f, and D* values among the L2, L3, and L4 vertebras of women or men. IVIM parameters can show differences in bone marrow between young women and men. As a non-invasive method, it can assess bone marrow microstructure, such as cellularity and perfusion.

Dissolution characteristics of uranium and lead in simulated lung fluid using fly ash samples from coal-fired power plants in the Czech Republic

Samples of fly ash, slag and boiler scale containing elevated amounts of uranium or lead (210Pb) from several coal-fired power stations in the Czech Republic were collected for an assessment of their dissolution parameters – the dissolution rates and their respective fractions in vitro. The dissolution data were fitted either by a biexponential model or by a triexponential model. The uranium 234U and 238U in the fly ash sample are classified as M-type. Similarly, type M could be attributed for most of the materials containing 210Pb. A complementary measurement of the activity concentrations of 210Pb in relation to the grain size confirmed that the radionuclide is deposited mainly in fine particles (<25 μm).

A three-component multi-b-value diffusion-weighted imaging might be a useful biomarker for detecting microstructural features in gliomas with differences in malignancy and IDH-1 mutation status.

The purpose of the study was to explore the performance of a three-component diffusion model in evaluating the degree of malignancy and isocitrate dehydrogenase 1 (IDH-1) gene type of gliomas. Overall, 60 patients with gliomas were enrolled. The intermediate and perfusion-related diffusion coefficients (Dint and Dp) and fractions of strictly limited, intermediate, and perfusion-related diffusion (Fvery-slow, Fint, and Fp) were obtained with a three-component diffusion model. Parameters were also obtained from a diffusion kurtosis model and mono- and biexponential models. All parameters were compared between different tumor grades and IDH-1 gene types. Diagnostic performance and logistic regression analyses were performed. High-grade gliomas (HGGs) had significantly higher Fint, Fvery-slow, and Dp values but significantly lower Fp and Dint values than low-grade gliomas (LGGs), and Fint and Fp differed significantly among grade II, III, and IV gliomas (p < 0.05 for all). Fint achieved the highest AUC of 0.872 in differentiating between LGGs and HGGs. Logistic regression analysis revealed that in each model, Fint, diffusion coefficient (D), apparent diffusion coefficient (ADC), mean diffusivity (MD), and mean kurtosis (MK) were associated with glioma grading. After multiple regression analysis, Fint remained the only differentiator. Additionally, Fint and Fp showed significant differences between IDH-1 mutated and IDH-1 wild-type gliomas (p = 0.007 and 0.01, respectively). The three-component DWI model served as a useful biomarker for detecting microstructural features in gliomas with different grades and IDH-1 mutation statuses. • The three-component model enables the estimation of an intermediate diffusion component. • The three-component model performed better than the other models in glioma grading and genotyping. • Fint was useful in evaluating the grade and genotype of gliomas.

Predicting tumor deposits in patients with rectal cancer: Using the models of multiple mathematical parameters derived from diffusion-weighted imaging

PurposeUsing mono-exponential, bi-exponential, and stretched-exponential models of multi-b-value diffusion-weighted imaging (DWI) to predict tumor depositions (TDs) in patients with rectal cancer (RC). Material and methodsThis retrospective study, between January 2018 and November 2021, enrolled 30 TDs-positive and 38 TDs-negative of patients with rectal cancer. The mathematical parameters including ADC from mono-exponential model, D, D* and f from bi-exponential model, and DDC and α from stretched-exponential model, clinical factors (such as age, gender, pathological stage, etc.) and image features (such as length, thickness, location, etc.) from tumor characteristics were obtained to identify the two groups of patients. The results were evaluated by the receiver operating characteristic curve (ROC) analysis and area under the ROC curve (AUC). Multivariate binary logistic regression analysis was conducted to determine the independent risk factors. ResultsThe D* and α values, pt. stage, tumor location, mesorecta fascia (MRF) / peritoneum status and percentage of rectal wall circumference invaded (PCI) were significantly different between the TDs-positive and TDs-negative groups (P < 0.001, P < 0.001, P = 0.029, P = 0.008, P < 0.001 and P = 0.002, respectively), with the AUC were 0.838, 0.901, 0.618, 0.698 0.694 and 0.758, respectively. The D* and α values were proved to be independent risk factors after multivariate binary logistic regression analysis (p = 0.022 and 0.004, respectively). The AUC of the model consisting of the D* and α values was 0.913 (95 % CI 0.820 ∼ 0.968).The combined model constructed by D*, α and tumor location demonstrated superior diagnostic performance, with the AUC, sensitivity, specificity, and accuracy of 0.947 (95 % confidence interval, CI, 0.865–0.987), 0.900, 0.868 and 0.853, respectively. ConclusionMultiple mathematical parameters can be used as preoperative auxiliary diagnostic tools to predict TDs of RC. The combined model constructed by D*, α and tumor location show better diagnostic performance for TDs.

The reliability of back-extrapolation in estimating in different swimming performances at the severe-intensity domain.

The amount of anerobic energy released during exercise might modify the initial phase of oxygen recovery (fast-O2debt) post-exercise. Therefore, the present study aimed to analyze the reliability of peak oxygen uptake estimate by back-extrapolation under different swimming conditions in the severe-intensity domain, verifying how the alterations of the recovery profile and anerobic energy demand might affect values. Twenty swimmers (16.7 ± 2.4years, 173.5 ± 10.2cm, and 66.4 ± 10.6kg) performed an incremental intermittent step protocol (IIST: 6 × 250 plus 1 × 200m, IIST_v200m) for the assessment of . The off-kinetics used a bi-exponential model to discriminate primary amplitude, time delay, and time constant (A1off, TD1off, and τoff) for assessment of fast-O2debt post IIST_v200m, 200-m single-trial (v200m), and rest-to-work transition at 90% delta (v90%Δ) tests. The linear regression estimated and the rate of recovery (BE-slope) post each swimming performance. The ANOVA (Sidak as post hoc) compared to the estimates of in v200m, IIST_v200m, and v90%Δ, and the coefficient of dispersion (R2) analyzed the association between tests. The values of during IIST did not differ from in v200m, IIST_v200m, and v90%Δ (55.7 ± 7.1 vs. 53.7 ± 8.2 vs. 56.3 ± 8.2 vs. 54.1 ± 9.1mlkg-1min-1, p > 0.05, respectively). However, the variance is moderately explained by only in IIST_v200m and v90%Δ (RAdj 2 = 0.44 and RAdj 2 = 0.43, p < 0.01). The TD1off and τoff responses post IIST_v200m were considerably lower than those in both v200m (6.1 ± 3.8 and 33.0 ± 9.5s vs. 10.9 ± 3.5 and 47.7 ± 7.9 s; p < 0.05) and v90%Δ ( 10.1 ± 3.8 and 44.3 ± 6.3 s, p < 0.05). The BE-slope post IIST_v200m was faster than inv200m andv90%Δ (-47.9 ± 14.6 vs. -33.0 ± 10.4 vs. -33.6 ± 13.8mlkg-1, p < 0.01), and the total anerobic (AnaerTotal) demand was lower in IIST_v200m (37.4 ± 9.4mlkg-1) than in 200m and 90%Δ (51.4 ± 9.4 and 46.2 ± 7.7mlkg-1, p < 0.01). Finally, the τ1off was related to AnaerTotal in IIST_v200m, v200m, and v90%Δ (r = 0.64, r = 0.61, and r = 0.64, p < 0.01). The initial phase of the recovery profile provided different (although reliable) conditions for the estimate of with BE procedures, which accounted for the moderate effect of anerobic release on off-kinetics, but compromised exceptionally the estimate in the 200-m single trial.

Sex-Related Differences in Oxygen Consumption Recovery After High-Intensity Rowing Exercise During Childhood and Adolescence.

To determine sex-related differences in oxygen consumption (V˙O2) recovery after high-intensity exercise during childhood and adolescence. Forty-two boys and 35 girls (10-17 y) performed a 60-second all-out test on a rowing ergometer. Postexercise V˙O2 recovery was analyzed from (1) the V˙O2 recovery time constant obtained from a biexponential model (τ1V˙O2) and (2) excess postexercise oxygen consumption calculated over a period of 8 minutes (EPOC8) and until τ1V˙O2 was reached (EPOCτ1). Multiplicative allometric modeling was used to assess the concurrent effects of body mass or lean body mass, and age on EPOC8 and EPOCτ1. EPOC8 increased significantly more in boys from the age of 14 years. However, the sex difference was no longer significant when EPOC8 was analyzed using an allometric model including body mass + age or lean body mass + age. In addition, despite a greater increase in EPOCτ1 in boys from the age of 14 years, τ1V˙O2 was not significantly different between sexes whatever age. While age and lean body mass accounted for the sex-related differences of EPOC during childhood and adolescence, no significant effect of age and sex was observed on the V˙O2 recovery time constant after high-intensity exercise.

An unsupervised convolutional neural network method for estimation of intravoxel incoherent motion parameters

Objective. Intravoxel incoherent motion (IVIM) imaging obtained by fitting a biexponential model to multiple b-value diffusion-weighted magnetic resonance imaging (DW-MRI) has been shown to be a promising tool for different clinical applications. Recently, several deep neural network (DNN) methods were proposed to generate IVIM imaging. Approach. In this study, we proposed an unsupervised convolutional neural network (CNN) method for estimation of IVIM parameters. We used both simulated and real abdominal DW-MRI data to evaluate the performance of the proposed CNN-based method, and compared the results with those obtained from a non-linear least-squares fit (TRR, trust-region reflective algorithm) and a feed-forward backward-propagation DNN-based method. Main results. The simulation results showed that both the DNN- and CNN-based methods had lower coefficients of variation than the TRR method, but the CNN-based method provided more accurate parameter estimates. The results obtained from real DW-MRI data showed that the TRR method produced many biased IVIM parameter estimates that hit the upper and lower parameter bounds. In contrast, both the DNN- and CNN-based methods yielded less biased IVIM parameter estimates. Overall, the perfusion fraction and diffusion coefficient obtained from the DNN- and CNN-based methods were close to literature values. However, compared with the CNN-based method, both the TRR and DNN-based methods tended to yield increased pseudodiffusion coefficients (55%–180%). Significance. Our preliminary results suggest that it is feasible to estimate IVIM parameters using CNN.