Clinical value of a radiomics model based on machine learning for the prediction of prostate cancer.

OBJECTIVE: Radiomics models have demonstrated good performance for the diagnosis and evaluation of prostate cancer (PCa). However, there are currently no validated imaging models that can predict PCa or clinically significant prostate cancer (csPCa). Therefore, we aimed to identify the best such models for the prediction of PCa and csPCa. METHODS: We performed a retrospective study of 942 patients with suspected PCa before they underwent prostate biopsy. MRI data were collected to manually segment suspicious regions of the tumor layer-by-layer. We then constructed models using the extracted imaging features. Finally, the clinical value of the models was evaluated. RESULTS: A diffusion-weighted imaging (DWI) plus apparent diffusion coefficient (ADC) random-forest model and a T2-weighted imaging plus ADC and DWI multilayer perceptron model were the best models for the prediction of PCa and csPCa, respectively. Areas under the curve (AUCs) of 0.942 and 0.999, respectively, were obtained for a training set. Internal validation yielded AUCs of 0.894 and 0.605, and external validation yielded AUCs of 0.732 and 0.623. CONCLUSION: Models based on machine learning comprising radiomic features and clinical indicators showed good predictive efficiency for PCa and csPCa. These findings demonstrate the utility of radiomic models for clinical decision-making.

Analysis of bone single-photon emission CT/CT and diffusion-weighted MR imaging in medication-related osteonecrosis of the jaw: focusing on the correlation between standardized uptake values and apparent diffusion coefficient values.

The purpose of this study is to investigate bone SPECT/CT and diffusion-weighted MR imaging (DWI) in medication-related osteonecrosis of the jaw (MRONJ), focusing on the correlation between standardized uptake values (SUVs) and apparent diffusion coefficient (ADC) values. Twenty-nine patients with MRONJ who underwent SPECT/CT and DWI were included in this study. SUVs (maximum and mean) with SPECT/CT, and ADC values (maximum, mean and minimum) with DWI were analyzed on characteristics in MRONJ, such as stage, location, medication and underlying disease, by Mann-Whitney U test. Furthermore, the correlation between SUVs and ADC values for characteristics in MRONJ were assessed by Spearman's rank correlation test for nonparametric data. A p-value lower than 0.05 was considered as statistically significant. SUVs and ADC values have no significant differences for all characteristics in MRONJ. Negative correlations were found in all cases and in stage 2 cases, and no correlations were found in stage 3 cases. In addition, negative correlations were found in maxillary cases, mandibular cases, non-bisphosphonate cases, osteoporosis cases, and malignant tumor cases. In conclusion, this study found multiple correlations between SUVs and ADC values in MRONJ, especially in stage 2. Suggesting that ADC values and SUVs may change with disease progression and the possibility of predicting MRONJ progression by SUVs and ADC values.

Relative contributions of mobility and partitioning to volatile fatty acid flux during electrodialysis.

Economically valuable volatile fatty acids (VFAs) are sustainably produced via fermentation processes. To use VFAs downstream, they must be recovered using technologies like electrodialysis (ED). Solute transport properties (i.e., partition coefficient (K), diffusion coefficient (D), and permeability (P=KD)) govern flux in ED. Therefore, to advance understanding of VFA flux through anion exchange membranes (AEMs) in ED, we aimed to elucidate the relative contributions of VFA partitioning and mobility to their flux. Accordingly, for VFAs of different sizes (C1-C5) and inorganic anions (Cl-, Br-), we measured their fluxes during ED, permeabilities, and partition coefficients, and calculated the diffusion coefficients. We then evaluated the correlations between flux and transport properties and between transport properties and anion physicochemical properties. Results showed VFA flux had a strong correlation with permeability (R2=0.94, p<0.01), consistent with flux described by the Nernst-Planck equation. Further, while there was a negative correlation between VFA flux and partition coefficient (R2=0.46, p=0.21), there was a positive correlation between VFA flux and diffusion coefficient (R2=0.95, p<0.01) which showed VFA mobility governed VFA flux. We observed a negative correlation between VFA diffusion coefficient and carbon-chain length which was attributed to steric hindrance, and a positive correlation between partition coefficient and carbon chain-length which we attributed to hydrophobicity and polarizability. This work provides fundamental insight on interactions between VFAs and AEMs which affect anion flux during ED.

The apparent diffusion coefficient based on small-field DWI is superior to T2-weighted imaging in evaluating neurological dysfunction of degenerative cervical myelopathy.

PURPOSE: To investigate the clinical application of zonally magnified oblique multislice (ZOOM) imaging technology in patients with degenerative cervical myelopathy (DCM) and compare it with T2WI imaging. METHODS: A total of 111 patients diagnosed with DCM were recruited. According to mJOA, patients with DCM were divided into ND + group with neurological dysfunction and ND- group without neurological dysfunction. Routine MRI and ZOOM-DWI were performed on 3.0 T MRI to obtain sagittal T2WI and apparent diffusion coefficient (ADC) diagram. ADC values of the narrow segment and its adjacent upper and lower segments were measured, and compared between the ND + and ND- groups. The correlation between ADC value of cervical spinal cord and mJOA score was analyzed. Additionally, ROC curves were plotted to calculate the AUC values. RESULTS: The comparison between ND + and ND- groups shows that there are significant differences in mJOA score, T2WI, anteroposterior diameter of spinal canal, ADC values of narrow, upper and lower segment (P < 0.05). In ND + group, there is a significant difference between ADC values of the narrow and its upper and lower segments (P < 0.001), while with no significant difference in ADC values of the upper and lower segments (P > 0.05). Results of correlation analysis indicate that in the ND + group, neurological dysfunction evaluated by mJOA scores is correlated with increased ADC values of the narrow segment (r = -0.52, P < 0.001), but not significantly correlated with ADC values of the upper and lower segments. Furthermore, T2WI, anteroposterior diameter of the spinal canal, and cervical cord ADC values all has diagnostic efficacy in evaluating neurological dysfunction in DCM (AUC > 0.5, P < 0.05), with the ADC value of the narrow segment being optimal. CONCLUSION: The ADC value of spinal cord obtained by small-field ZOOM-DWI can be used to evaluate neurological dysfunction in DCM, and is superior to traditional T2WI.

The potential role of breast MRI in evaluation of triple-negative breast cancer and fibroadenoma of less than 3 cm.

Background: The majority of small-sized (<3 cm) triple-negative breast cancer (TNBC) exhibit smooth margins upon palpation and are often oval or rounded masses. Distinguishing these masses preoperatively from fibroadenomas (FAs) would be very meaningful for clinical practice. The aim of our study was to evaluate the magnetic resonance imaging (MRI) appearance of TNBC and differentiate it from FAs. Methods: In this retrospective single-center study, we included 37 patients with TNBCs and 36 patients with FAs who underwent breast MRI. We employed the χ2 test and t-test to compare the differences in morphological features, dynamic contrast-enhanced MRI (DCE-MRI) parameters, and apparent diffusion coefficient (ADC) values between the two groups. Additionally, we constructed non-parametric receiver operating characteristic (ROC) curves using ADC values, with pathological results serving as the gold standard. Results: A total of 37 TNBC lesions and 39 FA lesions were included in the final analysis. TNBCs exhibited more frequent irregular shape, irregular margins, peritumoral edema, fast enhancement in the initial phase, rim enhancement, and time-signal intensity curve (TIC) type III compared to FAs (all P<0.05). Conversely, low-signal segregation in T2-weighted imaging (T2WI) and TIC type I were commonly found in FAs. The mean ADC value of TNBCs was significantly lower than that of FAs [(1.104±0.13)×10-3 vs. (1.613±0.16)×10-3 mm2/s, P<0.05]. The cutoff ADC for differentiating TNBCs from FAs was 1.239×10-3 mm2/s, yielding an area under the curve (AUC) of 0.997, a sensitivity of 94.6%, and a specificity of 100%. Conclusions: The morphological presentation of MRI, internal enhancement features of the mass, TIC curves, and ADC values provide valuable differential diagnostic information for TNBC and FA masses with a maximum diameter of less than 3 cm.

The role of multiparametric MRI in predicting lymphovascular invasion in breast cancer patients.

Background: This study aims to investigate the efficacy of multifactorial MRI in diagnosing breast cancer, specifically in the context of predicting lymphovascular invasion (LVI).Materials & methods: The patients were stratified into two groups: the primary group (100 patients) and the validation group (100 patients), based on essential characteristics. Multifactorial MRI, encompassing tumor size evaluation, diffusion coefficient assessment and dynamic contrast enhancement, was employed for patient examination.Results: Statistically significant differences were observed in tumor size, diffusion coefficient and dynamic contrast enhancement between groups with LVI (LVI+) and those without (LVI-). Key parameters were identified for predicting the degree of invasion.Conclusion: The results affirm the effectiveness of multifactorial MRI in forecasting LVI.

[Box: see text].

The Role of Diffusion-Weighted Imaging in Characterizing Benign and Malignant Breast Lesions: A Retrospective Study.

Introduction  Diffusion-weighted imaging (DWI) is a promising magnetic resonance imaging (MRI) technique for differentiating between benign and malignant breast lesions. This study set out to assess the diagnostic utility of DWI and apparent diffusion coefficient (ADC) values in the characterization of breast lesions. Materials and methods A retrospective analysis comprised 30 patients with breast lesions who had breast MRI with DWI. The histopathological findings, ADC readings, and conventional MRI features were all analyzed. The receiver operating characteristic (ROC) curve analysis method was utilized to assess the diagnostic accuracy of DWI. Results Out of the 30 lesions, 22 (73.3%) were benign and eight (26.7%) were malignant. Malignant lesions exhibited significantly lower ADC values (p < 0.001) compared to benign lesions. An ADC cutoff value of 1.1 × 10-3 mm2/s was optimal for differentiating benign from malignant lesions, yielding 90.81% sensitivity, 91.51% specificity, and 91.5% accuracy. Conclusion Combining DWI with quantitative ADC analysis is a helpful, non-invasive method for the characterization of breast lesions. It shows excellent diagnostic accuracy in identifying benign and malignant lesions, which may cut down on pointless biopsies and help with patient management.

Elucidating charge transfer process and enhancing electrochemical performance of laser-induced graphene via surface engineering with sustainable hydrogel membranes: An electrochemist's perspective.

Laser-induced graphene (LIG) has emerged as a promising solvent-free strategy for producing highly porous, 3D graphene structures, particularly for electrochemical applications. However, the unique character of LIG and hydrogel membrane (HM) coated LIG requires accounting for the specific conditions of its charge transfer process. This study investigates electron transfer kinetics and the electroactive surface area of LIG electrodes, finding efficient kinetics for the [Fe(CN)6]3-/4- redox process, with a high rate constant of 4.89 x 10-3 cm/s. The impact of polysaccharide HM coatings (cationic chitosan, neutral agarose and anionic sodium alginate) on LIG's charge transfer behavior is elucidated, considering factors like ohmic drop across porous LIG and Coulombic interactions/permeability affecting diffusion coefficient (D), estimated from amperometry.It was found that D of redox species is lower for HM-coated LIGs, and is the lowest for chitosan HM. Chitosan coating results in increased capacitive share in the total current while does not apparently reduce Faradaic current. Experimental findings are supported by ab-initio calculations showing an electrostatic potential map's negative charge distribution upon chitosan chain protonation, having an effect in over a two-fold redox current increase upon switching the pH from 7.48 to 1.73. This feature is absent for other studied HMs. It was also revealed that the chitosan's band gap was reduced to 3.07 eV upon acetylation, due to the introduction of a new LUMO state. This study summarizes the operating conditions enhanced by HM presence, impacting redox process kinetics and presenting unique challenges for prospective LIG/HM systems' electrochemical applications.

Simultaneous multislice echo-planar diffusion-weighted imaging (DWI) in patients with focal liver lesions: a comparative study with conventional DWI.

Background: Simultaneous multislice (SMS) technology improves acquisition efficiency of diffusion-weighted imaging (DWI). This study aimed to evaluate the performance of SMS-DWI in image quality and apparent diffusion coefficient (ADC) measurements for focal liver lesions (FLLs) as compared with that of conventional DWI (CON-DWI). Methods: The institutional ethics committee of West China Hospital, Sichuan University approved this single-center, prospective study conducted from February 2021 to March 2022. Free-breathing SMS-DWI and CON-DWI examinations were acquired on a 3-T scanner with b-values of 50, 400, and 800 s/mm2. Qualitative image quality and quantitative measurements of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and ADC were compared between SMS-DWI and CON-DWI. The ADC values for FLLs were further compared between SMS-DWI and CON-DWI in different patient subgroups. The intra- and interreader agreements were assessed. Significance was set at P<0.05. Results: This study included 116 patients (96 males, 20 females; mean age 52.0±10.7 years) with 119 FLLs. No significant differences were observed between SMS-DWI and CON-DWI regarding overall image quality in any b-value DWIs, and there were also no differences observed between SMS-DWI and CON-DWI (b=800 s/mm2) for either SNR or CNR (both P values >0.05). ADC values obtained from CON-DWI were higher than those from SMS-DWI in all FLLs [(1.31±0.47)×10-3 vs. (1.26±0.46)×10-3 mm2/s; P=0.004], and similar findings were observed across the different patient subgroups. The consistency analysis showed intrareader intraclass correlation coefficient (ICC) values of 0.792-0.944 and interreader ICC values of 0.758-0.861 for quantitative measurements (SNR, CNR, and ADC) and kappa values of 0.609-0.878 for qualitative image quality. Conclusions: SMS-DWI achieved a 37% reduction in scan time compared to CON-DWI while maintaining comparable overall image quality. Notably, the ADC values for FLLs were observed to be quantitatively lower with SMS-DWI.

Evaluation of malignancy in gallbladder tumors using the apparent diffusion coefficient obtained by diffusion­weighted MRI.

The utility of the apparent diffusion coefficient (ADC) of diffusion-weighted image (DWI) magnetic resonance imaging was examined for evaluating malignancy and prognosis in gallbladder tumors. A total of 63 patients (benign tumors, n=33; cancer, n=30) were included after surgical resection for gallbladder tumors, and their mean ADC values by DWI were obtained. Cases of advanced gallbladder cancer (n=25) were divided into ADCHigh and ADCLow groups, and clinicopathological factors were compared. In 63 cases, ADC values in advanced gallbladder cancer were significantly lower compared with benign tumors and non-advanced gallbladder cancer (P<0.05), and ADC values in early gallbladder cancer were also significantly lower compared with benign tumors (P<0.05). In 25 advanced gallbladder cancer cases, the ADCLow group tended to have a higher rate of advanced stage disease (P=0.09). Disease-free survival and overall survival (OS) of the ADCLow group were worse compared with the ADCHigh group (P<0.01). In the multivariate analysis of OS, poor differentiation and low ADC value were independent prognostic factors. ADC values may be useful for evaluating tumor malignancies in gallbladder tumors.

Values of apparent diffusion coefficient in pancreatic cancer patients receiving neoadjuvant therapy.

BACKGROUND: To investigate the values of apparent diffusion coefficient (ADC) for the treatment response evaluation in pancreatic cancer (PC) patients receiving neoadjuvant therapy (NAT). METHODS: This study included 103 NAT patients with histologically proven PC. ADC maps were generated using monoexponential diffusion-weighted imaging (b values: 50, 800 s/mm2). Tumors' minimum, maximum, and mean ADCs were measured and compared pre- and post-NAT. Variations in ADC values measured between pre- and post-NAT completion for NAT methods (chemotherapy, chemoradiotherapy), tumor locations (head/neck, body/tail), tumor regression grade (TRG) levels (0-2, 3), N stages (N0, N1/N2) and tumor resection margin status (R0, R1), were further analyzed. RESULTS: The minimum, maximum, and mean ADC values all increased dramatically after NAT, rising from 23.4 to 25.4% (all p < 0.001): mean (average: 1.626 × 10- 3 mm2/s vs. 1.315 × 10- 3 mm2/s), minimum (median: 1.274 × 10- 3 mm2/s vs. 1.034 × 10- 3 mm2/s), and maximum (average: 1.981 × 10- 3 mm2/s vs. 1.580 × 10- 3 mm2/s). The ADCs between the subgroups of all the criteria under investigation did not differ significantly for the minimum, maximum, or mean values pre- or post-NAT (P = 0.08 to 1.00). In the patients with borderline resectable PC (n = 47), the rate of tumor size changes after NAT was correlated with the pre-NAT mean ADC values (Spearman's coefficient: 0.288, P = 0.049). CONCLUSIONS: The ADC values of PC increased significantly following NAT; however, the percentage increases failed to provide any predictive value for the resection margin status or TRG levels.

The time threshold to reperfusion for DWI reversal in acute ischemic stroke depends on pre-interventional ADC value.

PURPOSE: The aims of this study are to explore the apparent diffusion coefficient (ADC)-dependent thresholds for time to reperfusion in reversible lesions following mechanical thrombectomy for acute ischemic stroke, and to investigate the associated risks of hemorrhagic transformation. METHODS: We conducted a retrospective case-control study, enrolling patients with large-vessel occlusion who underwent mechanical thrombectomy in Otaru General Hospital from 2016 to 2021. Reversible lesions were identified using volumetric ADC data, and the mean time from image to reperfusion (TIR) in each ADC range was compared between groups with and without reversible lesions, as well as those with and without parenchymal hematoma. The Wilcoxon rank sum test and chi-square test were used for comparison between two groups, and receiver operating characteristic curves were created to determine optimal thresholds. RESULTS: Seventy-five patients were included and 581 volumetric data were obtained. The mean TIR in the group with reversible lesions was shorter than in that without, and time thresholds were 131, 123 and 112 min for ADC values > 540 × 10-6, 500-540 × 10-6 and 440-500 × 10-6 mm2/s, respectively. Furthermore, in patients with parenchymal hematoma, the mean TIR was significantly longer, and the average ADC value was significantly lower than those without hematoma. CONCLUSION: The time thresholds for the irreversible ischemic core may vary depending on the ADC value, and they may be shorter when the ADC value is lower. Moreover, both the low ADC value and the late reperfusion might be associated with an increased risk of parenchymal hematoma.

Impact of fat content on lumbar spine DWI performance: A sex-based comparative study.

Purpose: Sex-based differences in lumbar spine's fat content in adults are minimal, but significant variations exist in diffusion-weighted imaging (DWI) signal characteristics. This study aimed to investigate fat content's impact on DWI performance in lumbar spine and potential sex differences. Methods: A retrospective analysis was conducted on upper abdominal MRI examinations in asymptomatic adult. The lumbar 1 vertebral apparent diffusion coefficient (ADC) values and fat fraction were measured. Using DWI images (b = 800 s/mm2), the lumbar 1 vertebral signal was categorized into high and iso-low signal groups. A univariate and multivariate analysis was conducted to investigate the influence of fat fraction on DWI performance. Finally, the participants were divided into three groups to analyze sex differences in the effect of fat content on DWI performance. Results: 202 subjects, 99 men were included. Fat content significantly influenced lumbar spine DWI signal in both sexes (p < 0.05). The effect on ADC values was significant only in women (p < 0.001). Women demonstrated a significantly higher proportion of high DWI signal than men in the low (p = 0.002) and middle (p = 0.012) fat content groups. Additionally, women had higher ADC values in the low fat group (p = 0.004) but lower values in the high fat group (p = 0.004). Conclusion: Fat content significantly impacts the DWI signal of lumbar spine, with a slight sex difference observed. These sex differences suggest that DWI signals may provide valuable information about the bone marrow beyond fat content.

Imaging of Ulcerative Colitis: The Role of Diffusion-Weighted Magnetic Resonance Imaging.

Magnetic resonance imaging (MRI) has emerged as a promising and appealing alternative to endoscopy in the objective assessment of patients with inflammatory bowel disease (IBD). Diffusion-weighted imaging (DWI) is a specialized imaging technique that enables the mapping of water molecule diffusion within biological tissues, eliminating the need for intravenous gadolinium contrast injection. It is expanding the capability of traditional MRI sequences in Ulcerative Colitis (UC). Recently, there has been growing interest in the application of intravoxel incoherent motion (IVIM) imaging in the field of IBD. This technique combines diffusion and perfusion information, making it a valuable tool for assessing IBD treatment response. Previous studies have extensively studied the use of DWI techniques for evaluating the severity of activity in IBD. However, the majority of these studies have primarily focused on Crohn's disease (CD), with only a limited number of reports specifically examining UC. Therefore, this review briefly introduces the basics of DWI and IVIM imaging and conducts a review of relevant studies that have investigated its application in UC to show whether these techniques are useful techniques for evaluating patients with UC in terms of detection, characterization, and quantification of disease activity. Through the extensive literature survey, most of these studies indicate that DWI proves valuable in the differential diagnosis of UC and could be used as an effective modality for staging UC.

Transient elastography and diffusion-weighted magnetic resonance imaging for assessment of liver fibrosis in children with chronic hepatitis C.

BACKGROUND: Chronic hepatitis C (CHC) is a health burden with consequent morbidity and mortality. Liver biopsy is the gold standard for evaluating fibrosis and assessing disease severity and prognostic purposes post-treatment. Noninvasive alternatives for liver biopsy such as transient elastography (TE) and diffusion-weighted magnetic resonance imaging (DW-MRI) are critical needs. AIM: To evaluate TE and DW-MRI as noninvasive tools for predicting liver fibrosis in children with CHC. METHODS: This prospective cross-sectional study initially recruited 100 children with CHC virus infection. Sixty-four children completed the full set of investigations including liver stiffness measurement (LSM) using TE and measurement of apparent diffusion coefficient (ADC) of the liver and spleen using DW-MRI. Liver biopsies were evaluated for fibrosis using Ishak scoring system. LSM and liver and spleen ADC were compared in different fibrosis stages and correlation analysis was performed with histopathological findings and other laboratory parameters. RESULTS: Most patients had moderate fibrosis (73.5%) while 26.5% had mild fibrosis. None had severe fibrosis or cirrhosis. The majority (68.8%) had mild activity, while only 7.8% had moderate activity. Ishak scores had a significant direct correlation with LSM (P = 0.008) and were negatively correlated with both liver and spleen ADC but with no statistical significance (P = 0.086 and P = 0.145, respectively). Similarly, histopathological activity correlated significantly with LSM (P = 0.002) but not with liver or spleen ADC (P = 0.84 and 0.98 respectively). LSM and liver ADC were able to significantly discriminate F3 from lower fibrosis stages (area under the curve = 0.700 and 0.747, respectively) with a better performance of liver ADC. CONCLUSION: TE and liver ADC were helpful in predicting significant fibrosis in children with chronic hepatitis C virus infection with a better performance of liver ADC.

Evaluation of apparent diffuse coefficient (ADC) with regards to reproducibility and diagnostic accuracy as well as possible significance of pre - and post - contrast acquisition and employment of different b values.

PURPOSE: Ongoing efforts are focusing on optimizing diffusion-weighted imaging (DWI) as an essential part of breast MRI protocol. Our study aimed to evaluate the effect of contrast media (CM) on the apparent diffusion coefficients (ADC) acquired following current recommendations. PATIENT AND METHODS: Patients who underwent 3 T breast MRI with a histologically verified suspicious lesion were included in this IRB-approved, single-center, cross-sectional retrospective study. Breast MRI protocol included a DWI sequence with multiple b-values, which was acquired before and after CM administration. ADC maps were calculated by in-line monoexponential fitting with b-values 0 /800 and 50/800. Two independent readers (R1, R2) reviewed the images in separate sessions for b values 0/800 and 50/800, pre- and post-CM. Bland Altmann plots as well as intraclass correlation coefficients (ICCs) for inter-reader agreement, different b-values, and pre- and post-CM were calculated. Diagnostic accuracy was evaluated and compared by calculating the area under the receiver operating characteristics curve (AUC). RESULTS: 91 lesions in 89 patients were examined (mean age 50.7 years, standard deviation 13.9). ADC values were significantly (P<0.05) lower post-CM (mean ranging from 1.28 x10-3 mm2/s to 1.30 x10-3 mm2/s) compared to pre-CM (mean ranging from 1.32 x10-3 mm2/s to 1.37 x10-3 mm2/s) for both b-values combinations (0/800 and 50/800 s/mm2). We found an almost perfect inter-reader agreement pre-/post-CM with b values 0/800 and 50/800 (ICC ranging from 0.853 to 0.939). Bland Altman plot demonstrated no systematic difference between readers. ROC analysis revealed good diagnostic performance without significant differences (P>0.05) between b values 0/800 and 50/800 s/mm2 as well as pre- and post-CM with areas under the ROC curve between 0.834 and 0.877. CONCLUSION: ADC values are slightly lower when acquiring b values 0/800 and post-CM. This effect does not reduce the diagnostic performance but may be relevant in case of definite cut-offs in medical decision making.

On the use of dioxane as reference for determination of the hydrodynamic radius by NMR spectroscopy.

Measuring the compaction of a protein or complex is key to our understanding of the interactions within and between biomolecules. Experimentally, protein compaction is often probed either by estimating the radius of gyration (Rg) obtained from small-angle X-ray scattering (SAXS) experiments or the hydrodynamic radius (Rh) obtained for example by pulsed field gradient nuclear magnetic resonance (PFG NMR) spectroscopy. PFG NMR experiments generally report on the translational diffusion coefficient, which in turn can be used to estimate Rh using an internal standard to account for sample viscosity and uncertainty about the gradient strength. 1,4-dioxane is one such commonly used internal standard, and the reference value of Rh is therefore important. We have revisited the basis for the commonly used reference value for the Rh of dioxane (2.12 Å) that is used to convert measured diffusion coefficients into a hydrodynamic radius. We followed the same approach that was used to establish the current reference value by measuring SAXS and PFG NMR data for a set of seven different proteins and using these as standards. Our analysis shows that the current Rh reference value for dioxane Rh is underestimated, and we instead suggest a new value of 2.27 Å ± 0.04 Å. Using this updated reference value results in a ∼7% increase in Rh values for proteins whose hydrodynamic radii have been measured by PFG NMR. These results are particularly important when the absolute value of Rh is of interest such as when determining or validating ensemble descriptions of intrinsically disordered proteins.

Role of diffusion tensor imaging in the evaluation of white matter integrity in idiopathic intracranial hypertension.

OBJECTIVES: To determine whether idiopathic intracranial hypertension (IIH) may affect white matter integrity and optic pathways by using diffusion tensor imaging (DTI) and to correlate the DTI metrics with intracranial pressure (ICP). METHODS: This study is a retrospective case-control study. A total of 42 patients who underwent lumbar puncture and those with elevated ICP, meeting the diagnostic criteria for IIH, were included in the study. All patients had supportive magnetic resonance imaging findings for the diagnosis of IIH. The headache control group comprised 36 patients who presented to the Neurology Department with infrequent episodic tension-type headache, had a normal neurologic examination, and had clinical and radiological findings suggestive of normal ICP. For each patient with IIH, clinical findings and ophthalmological measurements were recorded. The apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial diffusivity (AD), and radial diffusivity (RD) values were calculated using a region of interest-based method in different white matter tracts and optic pathways and compared. RESULTS: A total of 42 patients diagnosed with IIH (three males, 39 females), with a mean (standard deviation [SD] age of 38.1 (8.9) years), and 36 headache controls (10 males, 26 females, mean [SD] age; 38.1 [9.4] years) were included in the study. The mean (SD) body mass index (BMI) of the patients with IIH was 25.2 (1.9) kg/m2, and the mean (SD) BMI of the headache controls was 23.3 (1.5) kg/m2 (p < 0.001). Decreased FA values and increased RD values in the cingulum were detected in patients with IIH compared to the headache controls (p = 0.003, Cohen's d = 0.681; p = 0.002 Cohen's d = -0.710). Decreased AD values in the left and right superior cerebellar peduncle and increased ADC values in the middle cerebellar peduncle were detected in patients with IIH compared to the headache controls (p < 0.001, Cohen's d = 0.961; p = 0.009, Cohen's d = 0.607; p = 0.015, Cohen's d = -0.564). Increased ADC and RD values and decreased FA values in optic nerve were detected in patients with IIH (p = 0.010, Cohen's d = -0.603; p = 0.004, Cohen's d = -0.676; p = 0.015 Cohen's d = 0.568). A positive correlation was found between the cerebrospinal fluid pressure and ADC values of the left and right superior and left inferior longitudinal fasciculus, genu of the corpus callosum, and right optic radiation (r = 0.43, p = 0.005; r = 0.31, p = 0.044; r = 0.39, p = 0.010; r = 0.35, p = 0.024; r = 0,41, p = 0.007). There was a positive correlation between the retinal nerve fiber layer thickness and the ADC values of the optic nerve (r = 0.32, p = 0.039). CONCLUSIONS: Intracranial hypertension can be associated with deteriorated DTI values, which might be interpreted as a sign of impaired white matter microstructural integrity in many brain regions beyond the periventricular white matter. Pressure-induced edema and axonal degeneration may be the potential underlying mechanisms of this microstructural damage.

Application of a UV-vis spectrometer to investigate the effect of dissolution media on the diffusivity of small molecules and proteins.

To date, the commonly used methods for diffusion coefficient measurements have some hurdles that prevent them from being widely applied in pharmaceutical laboratories. This study aimed to modify a method developed by di Cagno et al. based on the use of a UV-Vis spectrometer and apply the method to investigate the effect of dissolution media on the diffusivity of small molecules and proteins. A total of five small molecules and two proteins in different aqueous media and polymer solutions were investigated in this study. By attaching a 3D-printed cover with an open slit to a standard UV-Vis cuvette, the incident UV light could only pass through the open slit to measure the local drug concentration. During the diffusion experiment, drug molecules diffused from the cuvette bottom to the slit. According to the concentration measured as a function of time, diffusion coefficient was calculated based on Fick's law of diffusion using the analytical and numerical approaches. As a result, diffusion coefficients could be accurately measured with high reproducibility. The results also suggested that different media could affect the diffusion coefficients of small molecules by < 10% and proteins by < 15%. Since the UV-Vis spectrometer is a routine instrument, this method can potentially be employed by many pharmaceutical laboratories for diffusion coefficient measurements.

Investigation of solvent extraction of acetic acid and acetone from water in the presence of SiO2 nanoparticles using molecular dynamics simulation.

In this study, molecular dynamics simulation was used to predict the molecular diffusion coefficient of acetic acid and acetone in water, toluene, and benzene. The results showed that COMPASS was the best force field to optimize the atoms and structure of molecules, and the results were compared with experimental equations. The Arrhenius behavior of the molecular diffusion coefficient was investigated at three temperatures. The extraction of acetic acid and acetone from water was investigated using two solvents, toluene, and benzene, with and without SiO2 nanoparticles. The relative concentration change diagram was drawn for three cases without and with SiO2 nanoparticles. To quantitatively examine the results, extraction efficiency, selectivity, and distribution coefficient were calculated. The extraction efficiency of acetone from water by benzene in the absence of silica nanoparticles was 65.748 %, this value in the presence of SiO2 nanoparticles with a concentration of 0.2231 wt% was 72.45 % due to the Brownian motion of the nanoparticles, which increased the mass transfer and as a result, the extraction efficiency. With the further increase of nanoparticles up to 1.7573 wt%, the extraction efficiency decreased to 61.276 %, which can be attributed to the accumulation of silica nanoparticles and the decrease in the free movement of nanoparticles.