Ve Values Research Articles

Dynamic contrast-enhanced MRI model selection for predicting tumor aggressiveness in papillary thyroid cancers.

The purpose of this study was to identify the optimal tracer kinetic model from T1 -weighted dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) data and evaluate whether parameters estimated from the optimal model predict tumor aggressiveness determined from histopathology in patients with papillary thyroid carcinoma (PTC) prior to surgery. In this prospective study, 18 PTC patients underwent pretreatment DCE-MRI on a 3T MR scanner prior to thyroidectomy. This study was approved by the institutional review board and informed consent was obtained from all patients. The two-compartment exchange model, compartmental tissue uptake model, extended Tofts model (ETM) and standard Tofts model were compared on a voxel-wise basis to determine the optimal model using the corrected Akaike information criterion (AICc) for PTC. The optimal model is the one with the lowest AICc. Statistical analysis included paired and unpaired t-tests and a one-way analysis of variance. Bonferroni correction was applied for multiple comparisons. Receiver operating characteristic (ROC) curves were generated from the optimal model parameters to differentiate PTC with and without aggressive features, and AUCs were compared. ETM performed best with the lowest AICc and the highest Akaike weight (0.44) among the four models. ETM was preferred in 44% of all 3419 voxels. The ETM estimates of Ktrans in PTCs with the aggressive feature extrathyroidal extension (ETE) were significantly higher than those without ETE (0.78±0.29 vs. 0.34±0.18min-1 , P = 0.005). From ROC analysis, cut-off values of Ktrans , ve and vp , which discriminated between PTCs with and without ETE, were determined at 0.45 min-1 , 0.28 and 0.014 respectively. The sensitivities and specificities were 86 and 82% (Ktrans ), 71 and 82% (ve ), and 86 and 55% (vp ), respectively. Their respective AUCs were 0.90, 0.71 and 0.71. We conclude that ETM Ktrans has shown potential to classify tumors with and without aggressive ETE in patients with PTC.

Influence of chlorine atom on thermodynamic and transport properties of binary liquid mixtures at various temperatures (halo-hydrocarbons and 2-methoxyaniline)

The densities (ρ), ultrasonic speeds (u), and viscosities (η) are reported for binary mixtures of o-chlorotoluene, m-chlorotoluene and p-chlorotoluene with 2-methoxy aniline at temperature range from (303.15–318.15) K and at a pressure p = 0.1 MPa. In addition, excess functions such as excess molar volume, excess isentropic compressibility and deviation in viscosity are calculated from the density, speed of sound and viscosity and the Redlich–Kister equation, correlates these properties. The excess partial molar volumes, and , and excess partial molar isentropic compressibilities, and of the components at infinite dilution are calculated. As well, the calculated excess properties were discussed in terms of the influence of chlorine atom on interactions between halo hydrocarbons and 2-methoxy aniline. Moreover, the VE values have been analysed with Prigogine-Flory-Patterson theory and shown that the free volume contribution is the supporting factor for negative values of excess molar quantities.

Imaging Biomarkers Multiparametric 3 Tesla MRI and FMISO Hypoxia PET during Chemoradiotherapy in HNSCC and Their Relation to Outcome

To prospectively assess in HNSCC patients the effect of chemoradiotherapy (CRT) on tumor hypoxia and tissue properties with [18F]FMISO PET/CT (FMISO PET) and multiparametric (mp) MRI at baseline and at an early (week 2) and late (week 5) time point during treatment and to analyze whether mpMRI and PET parameters are related with outcome. Patients with stage III to IVb HNSCC undergoing definitive CRT (total dose 70 Gy, 3 cycles of cisplatin over 7 weeks) were included. Patients were prospectively imaged with [18F]FDG PET/CT at baseline and with serial FMISO PET and serial 3 Tesla mpMRI for T1w-, T2w- as well as contrast-enhanced perfusion and diffusion-weighted measurements (ktrans, ve and apparent diffusion coefficient (ADC) maps) in weeks 0, 2 and 5. Patients were identified as responders or non-responders during follow-up regarding loco-regional control (LRC) and overall survival (OS). Tumor volumes were contoured and SUVmax FMISO PET and mean values for mpMRI parameters were compared between responders and non-responders with the t-test and Log Rank test at a significance level of p≤0.05. A complete set of serial FMISO PET data and 3 T MRI was available in 21 patients. Of those, 12 patients were diagnosed with local recurrence. Baseline tumor volume and FMISO-PET-derived tumor hypoxia (SUVmax FMISO) were higher among patients with local recurrence as compared to locally controlled patients (p=n.s.). On Kaplan-Meier analysis stratified at median change in SUVmax FMISO between weeks 0 to 5 (ΔFMISOwk0-5), LRC was higher for ΔFMISOwk0-5 > median (p=n.s.). For ADC, an increase was found from week 0 to 5 (responders > non-responders). LRC was significantly higher for patients with ΔADCwk0-5 and %ΔADCwk0-5 > median (Log Rank, p=0.04 and p=0.005). In perfusion MRI, ktrans increased from week 0 to 5 for both non-responders and responders (p=n.s.). For non-responders, ktrans reached a maximum at week 2, while for responders, ktrans showed a steady increase until week 5. Interstitial space volume fraction ve did not differ significantly between responders and non-responders and increased between week 0 and 5 (p=n.s.). Baseline ADC below median was significantly (p=0.013) correlated with improved OS. ADCweek2 below median was associated with improved OS (p=n.s.). Baseline ve below median was significantly correlated with improved OS (p=0.043) and associated with increased LRC (p=n.s.). Multiparametric MRI parameters ADC and interstitial space volume fraction ve obtained at baseline were significantly correlated with improved OS and an increase of ADC between week 0 to 5 was significantly correlated with improved LRC. FMISO-PET-derived tumor hypoxia and mean values of MRI parameters ktrans and ve differed between relapsing and non-relapsing patients, however without reaching statistical significance in this cohort. The correlations found for ve and ADC may suggest predictive power for OS and LRC depending on baseline imaging and the dynamics of ADC.

A study of dynamic contrast-enhanced MR imaging features and influence factors of pelvic bone marrow in adult females.

To investigate the effect of menstrual status and age on the perfusion of pelvic bone marrow in adult females using quantitative dynamic contrast-enhanced MRI (DCE-MRI). In total, 96 adult females who underwent DCE-MRI between September 2017 and December 2017 were included. All the subjects' quantitative DCE-MRI parameters of pelvic bone marrow were measured and retrospectively analyzed, including Ktrans (volume transfer constant), Kep (efflux rate constant), and Ve (interstitial volume). According to their menstrual status, the subjects were divided into a premenopausal group (n = 39) and a postmenopausal group (n = 57), and the two groups were then divided into four subgroups according to age. The intraobserver reliability was assessed by the intraclass correlation coefficient (ICC). The parameters were compared between different menstrual status groups and age subgroups by Mann-Whitney test, and Spearman correlation analysis was used to evaluate the correlation between the age and the quantitative parameters. The ICCs of the Ktrans, Kep, and Ve values were 0.989, 0.974, and 0.920, respectively. Ktrans, Kep, and Ve of the premenopausal group were significantly higher than those of the postmenopausal group (P < 0.05). The overall age was negatively correlated with Ktrans, Kep, and Ve (r = - 0.590, - 0.357, and - 0.381, respectively, P < 0.05). In the premenopausal group, Ktrans and Ve were significantly higher in subgroup 1 (≤ 40years) compared with subgroup 2 (> 40years) (P < 0.05), and age showed a negative correlation with Ktrans and Ve (r = - 0.344 and - 0.334, respectively, P < 0.05). In the postmenopausal group, Ktrans and Kep were significantly higher in subgroup 3 (≤ 60years) compared with subgroup 4 (> 60years) (P < 0.05), and age showed a negative correlation with Ktrans and Kep (r = - 0.460 and - 0.303, respectively, P < 0.05). Menstrual status and age have significant effects on the perfusion of the pelvic bone marrow microenvironment in adult females and that the microenvironment of the pelvic bone marrow displays different changes at different age stages. Quantitative DCE-MRI has contributed to the interpretation of the pelvic bone marrow perfusion status.

Value of diffusion-weighted and dynamic contrast-enhanced MR in predicting parametrial invasion in cervical stromal ring focally disrupted stage IB-IIA cervical cancers.

To compare the effectiveness of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) imaging in detecting parametrial invasion (PMI) in cervical stromal ring focally disrupted stage IB-IIA cervical cancers. Eighty-one patients with cervical stromal ring focally disrupted stage IB-IIA cervical cancers (PMI positive, n = 35; PMI negative, n = 46) who underwent preoperative MRI and radical hysterectomy were included in this study. Preoperative clinical variables and MRI variables were analyzed and compared. The Ktrans (min, mean, 10%, 25%, 50%, 75%, 90%), Kep (min, 10%, 25%, 50%, 75%, 90%), and Ve (min, 10%, 25%, 50%, 75%, 90%) values of patients with PMI were significantly higher than patients without PMI. The apparent diffusion coefficient (ADC) value did not show statistical difference between the two groups (1.01 ± 0.21 vs. 0.97 ± 0.20 10-3 mm2/s, p = 0.360). Tumor craniocaudal planes were higher in PMI-positive group than PMI-negative group (35.84 ± 15.39 vs. 29.70 ± 11.78mm, p = 0.048). Tumor craniocaudal planes combined with Kepmin value showed the highest area under the curve (AUCs) of 0.775, with a sensitivity of 72.7% and a specificity of 71.1% (p = 0.000). DCE parameters combined tumor craniocaudal planes may represent a prognostic indicator for PMI in cervical stromal ring focally disrupted IB-IIA cervical cancers.

Effect of the Temperature of Background Plasma and the Energy of Energetic Electrons on Z-mode Excitation

Abstract It has been suggested that the Z-mode instability driven by energetic electrons with a loss-cone type velocity distribution is one candidate process behind the continuum and zebra pattern of solar type-IV radio bursts. Both the temperature of background plasma (T 0) and the energy of energetic electrons (v e ) are considered to be important to the variation of the maximum growth rate (γ max). Here we present a detailed parameter study on the effect of T 0 and v e , within a regime of the frequency ratio ( ). In addition to γ max, we also analyze the effect on the corresponding wave frequency ( ) and propagation angle (θ max). We find that (1) γ max generally decreases with increasing v e , while its variation with T 0 is more complex depending on the exact value of v e . (2) With increasing T 0 and v e , presents stepwise profiles with jumps separated by gradual or very weak variations, and due to the warm plasma effect on the wave dispersion relation can vary within the hybrid band (the harmonic band containing the upper hybrid frequency) and the higher band. (3) The propagation is either perpendicular or quasi-perpendicular, and θ max presents variations in line with those of , as constrained by the resonance condition. We also examine the profiles of γ max with for different combinations of T 0 and v e to clarify some earlier calculations which show inconsistent results.

On the Regular Behavior of a Binary Mixture of Ionic Liquids.

Binary mixtures of the ionic liquids 1-ethyl-3-methylimidazolium dicyanamide and tributyl(methyl)ammonium dicyanamide, [C2C1im]x[N4441](1-x)[N(CN)2], are studied by means of their excess properties (enthalpy and volume), their viscosity, and their Raman spectra. The mixtures exhibit positive values of excess volume VE and excess enthalpy HE. The plot of the logarithm of viscosity as a function of composition is consistent with the finding HE > 0. The excess thermodynamic properties of the ionic liquid mixtures are compared with well-known results for binary mixtures of (high-temperature) molten salts. The asymmetry of the curve HE versus composition is reproduced by considering the volumetric fraction of the [C2C1im]x[N4441](1-x)[N(CN)2] mixtures according to basic results of the theory of regular solutions. The anion totally symmetric stretching mode νs(C≡N) was used to probe the local environment around the anion in a Raman spectroscopy investigation of the [C2C1im]x[N4441](1-x)[N(CN)2] mixtures as a function of the composition. The Raman band shape (peak frequency and bandwidth) of the νs(C≡N) mode changes as expected from the fluctuation of concentration around the probe oscillator according to models for vibrational spectroscopy of liquid mixtures. This thermodynamic and spectroscopic study leads to the classification of the [C2C1im]x[N4441](1-x)[N(CN)2] mixture as a regular solution. The application of the regular solution equation for HE to other ionic liquid binary mixtures is discussed.

DCE-MRI protocol for constraining absolute pharmacokinetic modeling errors within specific accuracy limits.

To quantify the effects of DCE acquisition and pharmacokinetic modeling processing methodologies on the absolute accuracy and precision of derived pharmacokinetic (PK) parameter values using a novel anthropomorphic phantom test device in which "ground truth" values were known a priori. Ground truth arterial input function (AIF), tumor, and healthy tissue contrast agent concentration-time curves (CTCs) were established within the phantom and repeatedly measured on a 3T MRI scanner with varying temporal resolution (Tres =1.22-30.6s). Ground truth CTCs, Ktrans , ve , and kep values were directly compared to measured values as a function of Tres , with and without the application of voxel-wise flip-angle corrections applied to the data and PK modeling performed using linear and nonlinear forms of the standard Tofts model. Measurement of the AIF was strongly affected by the Tres used (AIF curve-shape feature errors: 3%-222% for Tres : 1.22-30.6s), which directly translated to errors in the derived Ktrans , ve , and kep values of 1%-24%, 2%-5%, and 1%-26% respectively across this Tres range (flip-angle correction applied). Further appreciable improvements in accuracy and precision arising from the use of flip angle corrections and nonlinear least squares fitting were quantified and used to identify optimal acquisition and analysis methodologies for which measurement errors could be constrained below threshold levels. This quantitative study provides insight into how errors in AIF measurement propagate to errors in PK parameter outputs. Absolute quantification of the accuracy and precision of MR-measured CTCs, and resultant PK parameter values, allowed for an optimal temporal resolution to be defined commensurate with maintaining Ktrans , ve , and kep measurement errors below 5% and 10% levels. An appreciable gain in PK parameter estimation accuracy at the analysis stage was also demonstrated using flip-angle corrections and a linear approach to PK model fitting.

Intravoxel Incoherent Motion Diffusion-Weighted Imaging for Evaluation of the Cell Density and Angiogenesis of Cirrhosis-Related Nodules in an Experimental Rat Model: Comparison and Correlation With Dynamic Contrast-Enhanced MRI.

BackgroundIntravoxel incoherent motion diffusion‐weighted imaging (IVIM‐DWI) and dynamic contrast‐enhanced MRI (DCE‐MRI) are sensitive imaging modalities for detecting liver lesions, but their value in evaluating cirrhosis‐related nodules remains unclear.PurposeTo investigate whether IVIM‐DWI and DCE‐MRI can differentiate different types of cirrhosis‐related nodules, and whether these modalities can monitor changes in cell density and angiogenesis during the malignant transformation of cirrhosis‐related nodules in a rat modelStudy TypeProspective.Animal ModelThirty‐five male Sprague–Dawley rats with 106 cirrhosis‐related nodules (19 regenerative nodules [RNs], 47 dysplastic nodules [DNs], and 40 hepatocellular carcinomas [HCCs]).Field Strength/SequenceIVIM‐DWI and DCE sequence at 3.0T MRI.AssessmentIVIM‐DWI parameters (D, D*, f, and apparent diffusion coefficient [ADC]) and DCE‐MRI parameters (Ktrans, Kep, and Ve) were calculated by two radiologists using postprocessing software. The “cell density” and “unpaired arterial ratio” were analyzed with a microscope by two pathologists.Statistical TestsMRI parameters were compared among the different types of nodules by one‐way analysis of variance or the Kruskal–Wallis test. The Pearson correlation test was used to analyze the correlation of MRI parameters with the pathological types of nodules, cell density, and unpaired arterial ratio.ResultsThe Ktrans, Kep, and Ve values of HCCs were significantly higher than those of DNs and RNs. D and ADC values were significantly lower in HCCs than in DNs and RNs. There were moderate positive correlations of Ktrans with the pathological types of nodules and the unpaired arterial ratio. Moderate negative correlations were observed among D, ADC, and the pathological types of nodules, between D and cell density, and between ADC and cell density.Data ConclusionIVIM‐DWI and DCE‐MRI are valuable in differentiating different types of cirrhotic‐related nodules. D and ADC are correlated with changes in cell density during the malignant transformation of cirrhosis‐related nodules, while Ktrans is correlated with increased angiogenesis. Level of Evidence: 1 Technical Efficacy: Stage 1J. Magn. Reson. Imaging 2020;51:812–823.

Assessment of solid components of borderline ovarian tumor and stage I carcinoma: added value of combined diffusion- and perfusion-weighted magnetic resonance imaging.

BackgroundWe sought to determine the value of combining diffusion-weighted (DW) and perfusion-weighted (PW) sequences with a conventional magnetic resonance (MR) sequence to assess solid components of borderline ovarian tumors (BOTs) and stage I carcinomas.MethodsConventional, DW, and PW sequences in the tumor imaging studies of 70 patients (BOTs, n=38; stage I carcinomas, n=32) who underwent surgery with pathologic correlation were assessed. Two independent radiologists calculated the parameters apparent diffusion coefficient (ADC), Ktrans (vessel permeability), and Ve (cell density) for the solid components. The distribution on conventional MR sequence and mean, standard deviation, and 95% confidence interval of each DW and PW parameter were calculated. The inter-observer agreement among the two radiologists was assessed. Area under the receiver operating characteristic curve (AUC) and multivariate logistic regression were performed to compare the effectiveness of DW and PW sequences for average values and to characterize the diagnostic performance of combined DW and PW sequences.ResultsThere were excellent agreements for DW and PW parameters between radiologists. The distributions of ADC, Ktrans, and Ve values were significantly different between BOTs and stage I carcinomas, yielding AUCs of 0.58 and 0.68, 0.78 and 0.82, and 0.70 and 0.72, respectively, with ADC yielding the lowest diagnostic performance. The AUCs of the DW, PW, and combined PW and DW sequences were 0.71±0.05, 0.80±0.05, and 0.85±0.05, respectively.ConclusionCombining PW and DW sequences to a conventional sequence potentially improves the diagnostic accuracy in the differentiation of BOTs and stage I carcinomas.

Comparison of Maximal Aerobic Capacity Between the Treadmill and a Skiing Ergometer

Cross-country skiing is known to be an extremely aerobically demanding sport. Therefore, the use of a skiing ergometer (ie. SkiErg) to replicate similar aerobic training is increasing in use in lab and fitness settings. The SkiErg is widely used in gyms, research laboratories, and rehabilitation centers, and provides a low impact and total body cardiovascular and muscular endurance workout. Technique for training on the SkiErg can be quickly learned and adapted for immediate use by most individuals. Because of its lower cost and minimal required floor space, this piece of fitness equipment can be used at almost any location for exercise and training. Due to the benefits, convenience, and accessibility, the SkiErg may be a viable alternative max or peak graded exercise test (GXT) mode. To the best of the researchers’ knowledge, a comparison of aerobic capacity between a SkiErg and treadmill has not been assessed. PURPOSE: To compare treadmill (TM) VO2max values vs. those elicited from a SkiErg (SE) GXT. METHODS: Descriptive data (HT. = 176.1 + 8.2 cm, WT. = 80.5 + 10.1 kg, BF% = 15.1 + 5.8%, age = 22.7 + 2.4 yrs) was measured for 21 averagely fit college-age males. In a counterbalanced order and separated by 72 hours of rest, each subject completed 2 GXT protocols to the point of volitional exhaustion on a TM and SE. Max or peak values for VO2, HR, VE, and RER were compared between TM and SE using a Paired-Samples t-Test with an alpha level at p < 0.05. Peak RPE was compared using a Wilcoxon Signed Rank Test. RESULTS: TM was significantly greater than SE in regard to mean VO2max (51.1 ± 5.0 vs 44.5 ± 3.8 ml/kg/min, p < 0.01), HR (191 ± 11 vs 186 ± 10 bpm, p < 0.01), and RPE (19.6 + 2.2 vs 18.3 + 1.6, p = 0.039). TM was not significantly greater than SE regarding RER (1.2 + 0.0 vs 1.2 + 0.1, p = 0.862) or VE (146.2 + 16.5 vs 144.3 + 21.5 L/min, p = 0.614). CONCLUSIONS: The TM appears to yield higher max values for VO2, HR, RER, VE, and RPE values compared to SE in college-age males. Although TM elicited higher values than SE, SE VO2peak was only 15% lower than values measured from TM. This percent difference is comparable to other currently accepted alternative forms of aerobic capacity testing such as leg and arm cycle ergometers. Future studies should assess how gender, protocol variations, SE technique, or various athletic populations may impact VO2 values during a peak SE GXT.

Application of dynamic contrast enhanced MRI in the diagnosis of brucellar spondylitis

ObjectiveTo explore the value of Dynamic Contrast Enhanced(DCE) MRI in the clinical diagnosis, especially in the early stage of brucellar spondylitis. MethodsFifty six patients and ten healthy volunteers were included in this study. All the patients with brucellosis infections, ranged in age between thirty-five and sixty-two years old. This sample included thirty-two patients with brucellar spondylitis and twenty-four patients with strong back pain, however, the routine MRI showed no obvious abnormalities. The participants were scanned with routine MRI and DCE-MRI. The values of Ktrans,Kep,Ve, and Vp between the vertebral lesions of the patients suspected of brucellar spondylitis with no obvious abnormalities and the normal bodies in healthy volunteers were measured and compared. Under the Receiver Operating Characteristic(ROC) curve analysis, the sensitivity and specificity of the above four parameters were calculated. ResultsQuantitative parameters in this study have normal distribution and expressed as the mean (±standard deviation). The Ktrans, Kep, Ve and Vp values of the vertebral bodies in the pathological group were:(0.856 ± 0.539)ml/min, (1.482 ± 0.711)ml/min, (0.542 ± 0.267), and (0.034 ± 0.017), respectively. The normal vertebral bodies were (0.315 ± 0.298)ml/min, (0.713 ± 0.548)ml/min, (0.358 ± 0.259), and (0.056 ± 0.031), respectively. The differences between the two groups were statistically significant (P < 0.05). The values of Ktrans, Kep, Ve and Vp in the early lesion group were (0.666 ± 0.411) ml/min, (1.225 ± 0.824) ml/min, (0.429 ± 0.287) and (0.033 ± 0.025), respectively. Compared with the normal group, the values of Ktrans, Kep and Vp had significant difference (P < 0.5), and the values of Ve had no significant difference (P > 0.05); compared with the lesion group, the differences of Ktrans, Kep, Ve and Vp had no statistical significance (P > 0.05). The areas of Ktrans, Kep under the ROC curve were the largest. ConclusionThe DCE-MRI quantitative analysis plays an important role in the early diagnosis of brucellar spondylitis. This technique should be further studied and widely applied.

Monitoring tumour microenvironment changes during anti-angiogenesis therapy using functional MRI.

This study aims to explore the feasibility of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and blood oxygen level-dependent magnetic resonance imaging (BOLD-MRI) in assessing vessel function and tumour aggressiveness during anti-angiogenesis treatment. A colon cancer xenograft model was established in BALB/C nude mice with the HCT116 cell line. Sixteen mice were randomly divided into Group A and Group B, which were treated with saline or bevacizumab by intraperitoneal injection on the 1st, 4th, 7th, 10th and 13th days and underwent DCE-MRI and BOLD-MRI examinations before and on the 3rd, 6th, 9th, 12th and 15th days after treatment. Group C was treated with oxaliplatin monotherapy, and Group D was treated with bevacizumab and oxaliplatin as a point of comparison for therapeutic effects. The pathological examinations included HE, HIF-1α, fibronectin and TUNEL staining, as well as α-SMA and CD31 double staining. One-way analysis of variance and correlation analysis were the main methods used for statistical analysis. Group D manifested the highest tumour inhibition rate and smallest tumour volume on day 15, followed by Group C, Group B and Group A. Ktrans (F = 81.386, P < 0.001), Kep (F = 45.901, P < 0.001), Ve (F = 384.290, P < 0.001) and R2* values (F = 89.323, P < 0.001) showed meaningful trends with time in Group B but not Group A. The Ktrans values and tumour vessel maturity index (VMI) were higher than baseline values 3-12days after bevacizumab treatment. The CD31 positive staining rate and VMI had the strongest correlations with Ktrans values, followed by AUC180, Ve and Kep values. The R2* value positively correlated with the positive staining rates of HIF-1α and fibronectin. Intermittent application of low-dose anti-angiogenic inhibitor treatment may help improve the effect of chemotherapy by reducing hypoxia-related treatment resistance and improving drug delivery. DCE-MRI is useful for evaluating vessel maturity and vascular normalization, while BOLD-MRI may help to predict tumour hypoxia and metastatic potential after anti-vascular treatment.

Association between high-resolution MRI-detected extramural vascular invasion and tumour microcirculation estimated by dynamic contrast-enhanced MRI in rectal cancer: preliminary results

BackgroundTo determine whether magnetic resonance imaging (MRI)-detected extramural vascular invasion (mrEMVI) status is associated with quantitative perfusion parameters derived from dynamic contrast-enhanced MRI (DCE-MRI) in rectal cancer.MethodsSeventy-two patients with rectal adenocarcinoma who underwent curative surgery alone within 2 weeks following rectal MRI were enrolled in this retrospective study. mrEMVI status was determined based on high-resolution MRI. The quantitative perfusion parameters (Ktrans, kep and ve) derived from DCE-MRI were calculated from all sections containing tumours. DCE-MRI parameters and clinicopathological variables in patients with different mrEMVI statuses were compared.ResultsFor patients who were mrEMVI positive, the tumours demonstrated significantly lower kep values (P = 0.012) and higher ve values (P = 0.021) than tumours of patients who were mrEMVI negative, while the Ktrans value displayed no significant difference (P = 0.390). The patients who were mrEMVI positive had larger tumour size, higher pathological tumour stage and increased regional nodal metastases compared to those who were mrEMVI negative (2.9 cm vs. 3.5 cm, P = 0.011; 63.8% vs. 92.0%, P = 0.010; 36.2% vs. 76.0%, P = 0.001; respectively).ConclusionsThis study demonstrated for the first time that tumour microcirculation is altered in mrEMVI-positive patients with rectal adenocarcinoma, as evidenced by significantly lower kep and higher ve values. In addition, these patients were more likely to have a larger tumour size, a higher pathological tumour stage and regional nodal metastases than mrEMVI-negative patients.

Relationship between quantitative parameters of lumbar vertebral perfusion and bone mineral density (BMD) in postmenopausal women.

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a noninvasive method to evaluate the microcirculation of bone marrow in local tissue, which will be a new tool for the diagnosis of osteoporosis. To investigate the relationship between quantitative perfusion parameters (Ktrans, Kep and Ve) and bone mineral density (BMD) in postmenopausal women. The subjects were divided into 3 groups according to T value: normal bone mass group (T value ≥-1.0); bone loss group (-2.5 < T <-1.0); and osteoporosis group (T ≤-2.5). Ktrans, Kep and Ve of the lumbar spine were measured using quantitative DCE-MRI. The relationship between these parameters and age was analyzed. Bone mineral density of the lumbar spine and femoral neck gradually decreased with age. The values of Ktrans, Kep and Ve significantly decreased with age. The values of Ktrans, Kep and Ve of the lumbar vertebrae in the osteoporosis group were lower than those in the bone loss and normal bone mass group. Bone mineral density was positively correlated with the Ktrans and Ve of the lumbar vertebrae. The incidences of bone loss and osteoporosis increased with age. The measurement of BMD was conducive to early diagnosis of osteoporosis. Ktrans, Kep and Ve values of the lumbar vertebra decreased with age, and have a positive correlation with lumbar BMD. The value of DCE-MRI may play a role in the diagnostic algorithm of osteoporosis.

Prognostic Value of the Pretreatment Primary Lesion Quantitative Dynamic Contrast-Enhanced Magnetic Resonance Imaging for Nasopharyngeal Carcinoma

Early identifying the long-term outcome of chemoradiotherapy is helpful for personalized treatment in nasopharyngeal carcinoma (NPC). This study aimed to investigate the prognostic significance of pretreatment quantitative dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) for NPC. The relationships between the prognosis and pretreatment quantitative DCE-MRI (Ktrans, Kep, Ve, and fpv) values of the primary tumors were analyzed in 134 NPC patients who received chemoradiotherapy. Kaplan-Meier analysis was performed to calculate the local-regional relapse-free survival (LRRFS), local relapse-free survival (LRFS), regional relapse-free survival, distant metastasis-free survival (DMFS), progression-free survival, and overall survival rates. Cox proportional hazards model was used to explore the independent predictors for prognosis. The local-failure group had significantly higher Ve (p = 0.033) and fpv values (p = 0.005) than the non-local-failure group. The Ve-high group showed significantly lower LRRFS (p = 0.015) , LRFS (p = 0.013) , DMFS (p = 0.027) and progression-free survival (p = 0.035) rates than the Ve-low group. The fpv-high group exhibited significantly lower LRRFS (p = 0.004) and LRFS (p = 0.005) rates than the fpv-low group. Ve was the independent predictor for LRRFS (p = 0.008), LRFS (p = 0.007), DMFS (p = 0.041), and overall survival (p = 0.022). fpv was the independent indicator for LRRFS (p = 0.003) and LRFS (p = 0.001). Baseline quantitative DCE-MRI may be valuable in predicting the prognosis for NPC.

A thermodynamic investigation of solute - solvent interactions through volumetric, ultrasonic, dielectric, refractive and excess properties of binary mixtures of Tri-n-butyl phosphate with dichloro, trichloro and tetrachloromethane at 298.15 K

This study reports the density (ρ), molar volume(V),ultrasonic velocity (U), dielectric permittivity (ε), refractive index (nD) Kirkwood correlation factor (g/geff) and excess Helmholtz energy (∆AE) of binary mixtures of polar TBP (Tri-n-butyl phosphate) with polar CH2Cl2, CHCl3 and non-polar CCl4 over the entire range of mole fractions at 298.15 K. Several mixing rules have been applied to predict the ultrasonic velocity, dielectric permittivity and refractive index of the binary mixtures. The excess properties (VE, βsE, LfE, ZE, εE, PE and ∆nD) have been calculated in order to throw light on the kinds of molecular interactions existing in the binary systems. The experimentally obtained excess properties are fitted into Redlich-Kister polynomial equation. The negative values of VE and βsE for TBP and CCl4 mixtures resulted from the study may be attributed to dissimilar nature of the constituent molecules. In case of polar – polar TBP + CHCl3/CH2Cl2 mixtures, negative excess Helmholtz energy visualize anti parallel orientation of dipoles in TBP rich region.

Diagnostic performance of diffusion-weighted (DWI) and dynamic contrast-enhanced (DCE) MRI for the differentiation of benign from malignant soft-tissue tumors.

A wide range of specificity values for the differentiation of benign and malignant soft-tissue tumors show the limitations of conventional MRI features. The data obtained by quantitative analysis of diffusion-weighted image (DWI) and dynamic contrast-enhanced (DCE) MRIs would provide more objective results, especially in terms of cellularity and perfusion. To evaluate the diagnostic efficacies of DWI and DCE MRI for the differentiation of malignant and benign soft-tissue tumors. Retrospective. In all, 136 patients (68 females, 68 males; age range 18-86 years, mean age 57.2 years) with soft-tissue tumors. 3 T, DWI, DCE. Tumor sizes, margins, locations, the presence of involvement in bone or neurovascular bundle, peritumoral edema, heterogeneity, and tumor necrosis were investigated on conventional MR images. On DWIs, visual signal drops were assessed and ADC (apparent diffusion coefficient) values were measured. Ktrans , Kep , Ve , and iAUC values, and time-concentration curve (TCC) types were determined using DCE images. The data were statistically analyzed to determine the abilities to differentiate benign and malignant tumors using the chi-square test, two-sample t-test, and receiver operating characteristic (ROC) analysis. Seventy-three cases were malignant and 63 benign. Age (mean ages of benign/malignant tumors, 51.75/61.86 years; P = 0.0002) and gender (F:M = 40:23 [benign], F:M = 28:45 [malignant], P = 0.003) influenced the distinction between benign and malignant. Sizes, margins, neurovascular bundle involvement, peritumoral edema, and heterogeneity of the tumors on conventional MR images and DCE parameters (Ktrans , Kep , Ve , and iAUC, and TCC plots) obtained from focal region of interest within a narrow volume of interest significantly differentiated benign and malignant lesions (all P < 0.0001, except Ve [P = 0.0004]). For DWI with ADC mapping, all ADC values and visually signal drops were also significant (P < 0.0001). DWI and DCE-MRI and derived variables were significantly helpful in discriminating benign and malignant soft-tissue tumors complementary to conventional MRI. 3 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2019;50:798-809.

Intravoxel Incoherent Motion Combined With Dynamic Contrast-Enhanced Perfusion MRI of Early Cervical Carcinoma: Correlations Between Multimodal Parameters and HIF-1α Expression.

The identification of hypoxia inducible factor (HIF-1α) expression is helpful for the quantitative assessment of tumor hypoxia. The application of multimodal imaging techniques may play a part in the assessment of HIF-1α expression of cervical carcinoma. To investigate the correlations between multiple imaging parameters and HIF-1α expression of early cervical carcinoma and to determine whether tumor hypoxia can be predicted using multisequence imaging parameters. Prospective observational. One hundred patients with early cervical carcinoma. 3.0 T MRI including intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) perfusion MRI sequences. DCE-MRI and IVIM DWI were performed for all patients. The imaging parameters included volume transfer constant (Ktrans ), rate constant (Kep ), extravascular extracellular volume fraction (Ve ), D, D*, and f. The comparisons of imaging parameters between two independent groups were performed using the Mann-Whitney U-test. Multiple linear regression analysis was performed to determine the correlation between multiple imaging parameters and HIF-1α expression. The diagnostic ability of DCE-MRI, IVIM DWI, and the combination of two techniques for discriminating high-expression and low-expression groups were analyzed. The high-expression group had a lower Ktrans or Kep value than the low-expression group (P = 0.03; 0.02), while the high-expression group had a higher Ve value than the low-expression group (P = 0.03). The high-expression group had a higher D or f value than the low-expression group (P = 0.02; 0.02). Ktrans , Kep , D, Ve , and f values were independently correlated with HIF-1α expression. The sensitivity or accuracy of a combined method was higher than that of DCE-MRI or IVIM DWI individually (P = 0.03, 0.02; 0.04, 0.03). The combination of DCE-MRI and IVIM DWI can improve the diagnostic ability of discriminating different HIF-1α expression levels for early cervical tumors. 1 Technical Efficacy Stage: 2 J. Magn. Reson. Imaging 2019;50:918-929.

Robust estimation of hemo-dynamic parameters in traditional DCE-MRI models.

PurposeIn dynamic contrast enhanced (DCE) MRI, separation of signal contributions from perfusion and leakage requires robust estimation of parameters in a pharmacokinetic model. We present and quantify the performance of a method to compute tissue hemodynamic parameters from DCE data using established pharmacokinetic models.MethodsWe propose a Bayesian scheme to obtain perfusion metrics from DCE MRI data. Initial performance is assessed through digital phantoms of the extended Tofts model (ETM) and the two-compartment exchange model (2CXM), comparing the Bayesian scheme to the standard Levenberg-Marquardt (LM) algorithm. Digital phantoms are also invoked to identify limitations in the pharmacokinetic models related to measurement conditions. Using computed maps of the extra vascular volume (ve) from 19 glioma patients, we analyze differences in the number of un-physiological high-intensity ve values for both ETM and 2CXM, using a one-tailed paired t-test assuming un-equal variance.ResultsThe Bayesian parameter estimation scheme demonstrated superior performance over the LM technique in the digital phantom simulations. In addition, we identified limitations in parameter reliability in relation to scan duration for the 2CXM. DCE data for glioma and cervical cancer patients was analyzed with both algorithms and demonstrated improvement in image readability for the Bayesian method. The Bayesian method demonstrated significantly fewer non-physiological high-intensity ve values for the ETM (p<0.0001) and the 2CXM (p<0.0001).ConclusionWe have demonstrated substantial improvement of the perceptive quality of pharmacokinetic parameters from advanced compartment models using the Bayesian parameter estimation scheme as compared to the LM technique.