Intravoxel incoherent motion magnetic resonance imaging for breast cancer: A comparison with molecular subtypes and histological grades

PurposeThe purpose of this paper is to investigate whether the IVIM parameters (D, D *, f) helps to determine the molecular subtypes and histological grades of breast cancer.MethodsFifty-one patients with breast cancer were included in the study. All subjects were examined by 3 T Magnetic Resonance Imaging (MRI). Diffusion-weighted imaging (DWI) was undertaken with 16 b-values. IVIM parameters [D (true diffusion coefficient), D* (pseudo-diffusion coefficient), f (perfusion fraction)] were calculated. Histopathological reports were reviewed to histological grade, histological type, and immunohistochemistry. IVIM parameters of tumors with different histological grades and molecular subtypes were compared.ResultsD* and f were significantly different between molecular subtypes (p = 0.019, p = 0.03 respectively). D* and f were higher in the HER-2 group and lower in Triple negative (−) group (D*:36.8 × 10⁻³ ± 5.3 × 10⁻³ mm²/s, f:29.5%, D*:29.8 × 10⁻³ ± 5.6 × 10⁻³ mm²/s, f:21.5% respectively). There was a significant difference in D* and f between HER-2 and Triple (−) subgroups (p = 0,028, p = 0.024, respectively). D* was also significantly different between the HER-2 group and the Luminal group (p = 0,041). While histological grades increase, D and f values tend to decrease, and D* tends to increase. While the Ki-67 index increases, D* and f values tend to increase, and D tend to decrease.ConclusionD* and f values measured with IVIM imaging were useful for assessing breast cancer molecular subtyping. IVIM imaging may be an alternative to breast biopsy for sub-typing of breast cancer with further research.     

Correlation study between intravoxel incoherent motion MRI and dynamic contrast-enhanced MRI in head and neck squamous cell carcinoma: Evaluation in primary tumors and metastatic nodes

ObjectiveTo correlate intravoxel incoherent motion (IVIM) imaging and dynamic contrast-enhanced (DCE) MRI in head and neck squamous cell carcinoma (HNSCC).MethodsForty untreated patients with HNSCC were included retrospectively in the study. Perfusion fraction f, diffusion coefficient D and perfusion-related diffusion coefficient D* were extracted by bi-exponential fitting of IVIM data. Semi-quantitative DCE-MRI parameters, including positive enhancement integral (PEI) and maximum slope of increase (MSI), were calculated. The relationships between all variables were assessed by Spearman's test for correlation.Results27 primary tumors (PTs) and 23 lymph nodes (LNs) were analyzed. The residual sum of squares (RSS), used to assess the fit quality, was significantly different between PTs and LNs, with the last showing lower values. In LNs, D* and the product D* × f were positively related to both nPEI and nMSI, while no significant correlation was found in PTs.ConclusionEvident relationships between D* and D* × f and DCE-MRI perfusion measurements were found in LNs, while no significant association emerged in PTs. This presumably is due to the poorer agreement between the experimental data and curve fitting for PTs, as compared to LNs. Additional work is warranted to improve the reliability of the IVIM parameter estimations in primary HNSCCs.     

Three-dimensional turbo-spin-echo amide proton transfer-weighted and intravoxel incoherent motion MR imaging for type I endometrial carcinoma: Correlation with Ki-67 proliferation status

BackgroundTo evaluate 3-dimensional amide proton transfer weighted (APTw) imaging for type I endometrial carcinoma (EC), and investigate correlations of Ki-67 labelling index with APTw and intravoxel incoherent motion (IVIM) imaging.Methods54 consecutive patients suspected of endometrial lesions underwent pelvic APTw and IVIM imaging on a 3 T MR scanner. APTw values and IVIM-derived parameters (Dt, D*, f) were independently measured by two radiologists on 22 postoperative pathological confirmed of type I EC lesions. Results were compared between histological grades and Ki-67 proliferation groups. ROC analysis was performed. Pearson's correlation analysis was performed for APTw values and IVIM-derived parameters with Ki-67 labeling index.ResultsAPTw values and Dt, D*, f of all type I EC were 2.9 ± 0.1%, 0.677 ± 0.027 × 10⁻³ mm²/s, 31.801 ± 11.492 × 10⁻³ mm²/s, 0.179 ± 0.050 with inter-observer ICC 0.996, 0.850, 0.956, 0.995, respectively. APTw values of Ki-67 low-proliferation group (<30%, n = 8) were 2.5 ± 0.2%, significantly lower than the high-proliferation group (>30%, n = 14) with APTw values of 3.1 ± 0.1% (p = 0.016). Area under the curve was 0.768. APTw values of type I EC were moderately positively correlated with Ki-67 labelling index (r = 0.583, p = 0.004). There was no significant difference of Dt (p = 0.843), D* (p = 0.262), f (p = 0.553) between the two groups. No correlation was found between IVIM-derived parameters and Ki-67 labelling index (Dt, p = 0.717; D* p = 0.151; f, p = 0.153).Conclusion3D TSE APTw imaging is a feasible approach for detecting type I EC. Ki-67 labeling index positively moderately correlates with APTw not with IVIM.     

Assessment of the link between quantitative biexponential diffusion-weighted imaging and contrast-enhanced MRI in the liver

PurposeTo investigate if intravoxel incoherent motion (IVIM) modeled diffusion-weighted imaging (DWI) can be linked to contrast-enhanced (CE-)MRI in liver parenchyma and liver lesions.MethodsTwenty-five patients underwent IVIM-DWI followed by multiphase CE-MRI using Gd-EOB-DTPA (n = 20) or Gd-DOTA (n = 5) concluded with IVIM-DWI. Diffusion (D_slow), microperfusion (D_fast), its fraction (f_fast), wash-in-rate (R_early) and late-enhancement-rate (R_late) of Gd-EOB-DTPA were calculated voxel-wise for the liver. Parenchyma and lesions were segmented. Pre-contrast IVIM was compared 1) between low, medium and high R_early for parenchyma 2) to post-contrast IVIM substantiated with simulations 3) between low and high R_late per lesion type.ResultsD_fast and f_fast increased (P < 0.001) with 25.6% and 33.8% between low and high R_early of Gd-EOB-DTPA. D_slow decreased (− 15.0%; P < 0.001) with increasing R_early. Gd-DOTA demonstrated similar observations. f_fast (+ 10%; P < 0.001) and D_fast (+ 6.6%; P < 0.001) increased after Gd-EOB-DTPA, while decreasing after Gd-DOTA (− 4.2% and − 5.7%, P < 0.001) and were confirmed by simulations. For focal nodular hyperplasia lesions (n = 5) D_fast and f_fast increased (P < 0.001) with increasing R_late, whereas for hepatocellular carcinoma (n = 4) and adenoma (n = 7) no differences were found.ConclusionMicroperfusion measured by IVIM reflects perfusion in a way resembling CE-MRI. Also IVIM separated intra- and extracellular MR contrast media. This underlines the potential of IVIM in quantitative liver imaging.     

Diffusion tensor imaging of oral carcinoma: Clinical evaluation and comparison with histopathological findings

PurposeThis study aims to assess the usefulness of diffusion tensor imaging (DTI) as a noninvasive method for the evaluation of histological grade and lymph node metastasis in patients with oral carcinoma (OC).Materials and methodsThirty-six consecutive patients with histologically confirmed OC underwent examination by 3-T MRI. DTI was performed using a single-shot echo-planar imaging sequence with b values of 0 and 1000 s/mm² and motion-probing gradients in 12 noncollinear directions. Fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) maps were compared with histopathological findings. The DTI parameters were correlated with the histological grade of the OCs based on the World Health Organization grading criteria and the presence or absence of lymph node metastasis.ResultsThe FA values (0.275 ± 0.058) of OC were significantly lower than those of normal tongue, muscle, and parotid glands (P < 0.001 for all), and the MD, AD, and RD values (1.220 ± 0.149, 1.434 ± 0.172, and 1.019 ± 0.165 × 10⁻³ mm²/s, respectively) were significantly higher than their respective normal values (P < 0.001 for all). Significant inverse correlations with histological grades were shown for FA, MD, AD, and RD values in OC patients (r = −0.862, r = −0.797, r = −0.747, and r = −0.844, respectively; P < 0.001 for all). In addition, there was a significant difference in the FA values of metastatic and nonmetastatic lymph nodes (0.186 vs. 0.276), MD (0.923 vs. 1.242 × 10⁻³ mm²/s), AD (1.246 vs. 1.621 × 10⁻³ mm²/s), and RD (0.792 vs. 1.100 × 10⁻³ mm²/s; P < 0.001 for all).ConclusionsDTI may be clinically useful for the noninvasive evaluation of histological grade and lymph node metastasis in OC patients.     

A Boubaker polynomials expansion scheme (BPES)-related protocol for measuring sprayed thin films thermal characteristics

Measurements of In₂S₃ and ZnIn₂S₄ sprayed thin films thermal characteristics have been carried out using the photodetection technique. The thermal conductivity k and diffusivity D were obtained using a new protocol based on photothermal signal parameters analysis. Measured values of k and D were respectively, (15.2 ± 0.85) W m⁻¹K⁻¹ and (69.8 ± 7.1) × 10⁻⁶ m²s⁻¹ for In₂S₃, (7.2 ± 0.7) W m⁻¹K⁻¹ and (32.7 ± 4.3) × 10⁻⁶ m²s⁻¹ for ZnIn₂S₄. These values are extremely important since similar compounds are more and more proposed as Cd-free alternative materials for solar cells buffer layers.     

Usefulness of diffusion derived vessel density computed from a simplified IVIM imaging protocol: An experimental study with rat biliary duct blockage induced liver fibrosis

ObjectivesLiver vessel density can be evaluated by DDVD (diffusion derived vessel density): DDVD_(b0b1) = Sb0/ROIarea0 – Sb1/ROIarea1, where Sb0 and Sb1 refer to the liver signal when b is 0 or 1 s/mm². Sb1 and ROIarea1 may be replaced by other b-values. With a rat biliary duct ligation (BDL) model, this study assesses the usefulness of liver DDVD computed from a simplified IVIM imaging protocol using b = 25 and b = 50 to replace b = 1 s/mm², alone and in combination with other IVIM parameters.MethodsMale Sprague-Dawley rats were used. The rat number was 5, 5, 5, and 3 respectively, for the timepoints of 7, 14, 21, 28 days post-BDL surgery. 12 rats had partial biliary duct recanalization performed after the rats had BDL for 7 days and then again followed-up for a mean of 14 days. Liver diffusion MRIs were acquired at 3.0 T with a b-value distribution of 0, 25, 50, 75, 100, 150, 300, 700, 1000 s/mm². DDVD_mean (control rats n = 6) was the mean of DDVD_(b0b25) and DDVD_(b0b50). IVIM fitting started from b = 0 s/mm² with segmented fitting and a threshold b of 50 s/mm² (n = 5 for control rats). Three 3-D spaces were constructed using a combination of the four diffusion parameters.ResultsThe control rats and BDL rats (n = 18) had a liver DDVD_mean of 84.0 ± 26.2 and 44.7 ± 14.4 au/pixel (p < 0.001). All 3-D spaces totally separated healthy livers and all fibrotic livers (n = 30, BDL rats and recanalization rats). The mean relative distance between healthy liver cluster and fibrotic liver cluster was 0.331 for PF, D_slow, and D_fast; 0.381 for PF, D_fast, and DDVD_mean; and 0.384 for PF, D_slow, and DDVD_mean.ConclusionA combination of PF, D_slow, and D_fast allows total separation of healthy livers and fibrotic livers and the integration of DDVD improved the separation.     

Measurement of the D0, D+ and Ds+ meson lifetimes at √s = 10.58 GeV

We have measured the lifetimes of the D⁰, D⁺ and D_s⁺ mesons with data from the CLEO detector. We find τ_D⁰ = (5.0 ± 0.7 ± 0.4) × 10⁻¹³s, τ_D⁺ = (11.4 ± 1.6 ± 0.7) × 10⁻¹³s and τ_Ds⁺ = (4.7 ± 2.2 ± 0.5) × 10⁻¹³s, giving lifetime ratios τ_D⁺/τ_D⁰ = 2.3 ± 0.5 and τ_Ds⁺/τ_D⁰ = 0.9 ± 0.5.     

Tiny golden angle stack-of-stars (tygaSoS) free-breathing functional lung imaging

PurposeMRI of the lung parenchyma is still challenging due to cardiac and respiratory motion, and the low proton density and short T₂*. Clinical feasible MRI methods for functional lung assessment are of great interest. It was the objective of this study to evaluate the potential of combining the ultra-short echo-time stack-of-stars approach with tiny golden angle (tyGASoS) profile ordering for self-gated free-breathing lung imaging.MethodsFree-breathing tyGASoS data were acquired in 10 healthy volunteers (3 smoker (S), 7 non-smoker (NS)). Images in different respiratory phases were reconstructed applying an image-based self-gating technique. Resulting image quality and sharpness, and parenchyma visibility were qualitatively scored by three blinded independent reader, and the signal-to-noise ratio (SNR), proton fraction (f_P) and fractional ventilation (FV) quantified.ResultThe imaging protocol was well tolerated by all volunteers. Image quality was sufficient for subsequent quantitative analysis in all cases with good to excellent inter-reader reliability. Between expiration (EX) and inspiration (IN) significant differences (p < 0.001) were observed in SNR (EX: 3.73 ± 0.89, IN: 3.14 ± 0.74) and f_P (EX: 0.27 ± 0.09, IN: 0.25 ± 0.08). A significant (p < 0.05) higher f_P (EX/IN: 0.22 ± 0.07/0.21 ± 0.07 (NS), 0.33 ± 0.07/0.30 ± 0.06 (S)) was observed in the smoker group. No significant FV differences resulted between S and NS.ConclusionThe study proves the feasibility of free-breathing tyGASoS for multiphase lung imaging. Changes in f_P may indicate an initial response in the smoker group and as such proves the sensitivity of the proposed technique. A major limitation in FV quantification rises from the large inter-subject variability of breathing patterns and amplitudes, requiring further consideration.     

Oxygen diffusion and surface exchange studies on (La0.75Sr0.25)0.95Cr0.5Mn0.5O3−δ

Oxygen tracer diffusion coefficient (D^⁎) and surface exchange coefficient (k^⁎) have been measured for (La_0.75Sr_0.25)_0.95Cr_0.5Mn_0.5O_3−δ using isotopic exchange and depth profiling by secondary ion mass spectrometry technique as a function of temperature (700–1000 °C) in dry oxygen and in a water vapour-forming gas mixture. The typical values of D^⁎ under oxidising and reducing conditions at ∼ 1000 °C are 4 × 10^− 10 cm² s^− 1 and 3 × 10^− 8 cm² s^− 1 respectively, whereas the values of k^⁎ under oxidising and reducing conditions at ∼ 1000 °C are 5 × 10^− 8 cm s^− 1 and 4 × 10^− 8 cm s^− 1 respectively. The apparent activation energies for D^⁎ in oxidising and reducing conditions are 0.8 eV and 1.9 eV respectively.     

In vivo multiparametric magnetic resonance imaging study for differentiating the severity of hepatic warm ischemia-reperfusion injury in a rabbit model

ObjectivesTo assess the value of multiparametric magnetic resonance imaging including intravoxel incoherent motion (IVIM), diffusion tensor imaging (DTI) and blood oxygen level dependent (BOLD) MRI in differentiating the severity of hepatic warm ischemia-reperfusion injury (WIRI) in a rabbit model.MethodsFifty rabbits were randomly divided into a sham-operation group and four test groups (n = 10 for each group) according to different hepatic warm ischemia times. IVIM, DTI and BOLD MRI were performed on a 3 T MR scanner with 11 b values (0 to 800 s/mm²), 2 b values (0 and 500 s/mm²) on 12 diffusion directions, multiple-echo gradient echo (GRE) sequences (TR/TE, 75/2.57–24.25 ms), respectively. IVIM, DTI and BOLD MRI parameters, hepatic biochemical and histopathological parameters were compared. Pearson and Spearman correlation methods were performed to assess the correlation between these MRI parameters and laboratory parameters. Furthermore, receiver operating characteristic (ROC) curves were compiled to determine diagnostic efficacies.ResultsTrue diffusion (Dslow), pseudodiffusion (Dfast), perfusion fraction (PF), mean diffusivity (MD) significantly decreased, while R2* significantly increased with prolonged warm ischemia times, and significant differences were found in all of biochemical and histopathological parameters (all P < 0.05). Dslow, PF, and R2* correlated significantly with all of biochemical and histopathological parameters (all |r| = 0.381–0.746, all P < 0.05). ROC analysis showed that the area under the ROC curve (AUC) of IVIM across hepatic WIRI groups was the largest among IVIM, DTI and BOLD.ConclusionsMultiparametric MRI may be helpful with characterization of early changes and determination of severity of hepatic WIRI in a rabbit model.     

3 MeV electron irradiation-induced defects in CuInSe2 thin films

3 MeV electron irradiation induced-defects in CuInSe₂ (CIS) thin films have been investigated. Both of the carrier concentration and Hall mobility were decreased as the electron fluence exceeded 1×10¹⁷ cm⁻². The carrier removal rate was estimated to be about 1 cm⁻¹. To evaluate electron irradiation-induced defect, the electrical properties of CIS thin films before and after irradiation were investigated between 80 and 300 K. From the temperature dependence of the carrier concentration in non-irradiated thin films, we obtained N_D=1.8×10¹⁷ cm⁻³, N_A=1.7×10¹⁶ cm⁻³ and E_D=18 meV from the SALS fitting to the experimental data on the basis of the charge balance equation. After irradiation, a new defect level was formed, and N_T0=1.4×10¹⁷ cm⁻³ and E_T=54 meV were also obtained from the same procedure. From the temperature dependence of Hall mobility, the ionized impurity density was discussed before and after the irradiation.     

Synergetic effects of ultrasound and sodium alginate coating on mass transfer and qualities of osmotic dehydrated pumpkin

This research studied the effects of combined ultrasound and 3% sodium alginate (SA) coating pretreatment (US + Coat) on mass transfer kinetics, quality aspects, and cell structure of osmotic dehydrated (OD) pumpkin. The results of the pretreatment were compared with the results of control (non-pretreated osmotic dehydration) and other three pretreatment methods, which were 1) ultrasound in distilled water for 10 min (USC), 2) ultrasound in 70% (w/w) sucrose solution (US) for 10, 20 and 30 min, and 3) coating with 1%, 2%, 3% (w/w) SA. The coating pretreatments with SA resulted in a higher water loss (WL) but lower water activity and solid gain (SG) than other treatments. US pretreatments resulted in the highest effective diffusion coefficients of water (D_w) and solid (D_s) but the cell structure of the product was deformed. The 3% SA coating treatment had the highest WL/SG (5.28) but with the longest OD time (12 h). Using the US + Coat pretreatment gave satisfactory high WL/SG (5.18), D_w (1.09 × 10⁻¹⁰ m²s⁻¹) and D_s (5.15 × 10⁻¹¹ m²s⁻¹), reduced the OD time to 9 h, and preserved the cell structure of the product. This research suggests that US + Coat pretreatment can be an effective processing step in the production of OD pumpkin.     

Diffusion of Fe,Co, Nd,and Dy in R2(Fe1−xCox)14B where R=Nd or Dy

Transition metal and rare earth diffusion coefficients at 1323 K in Dy_2−yNd_y(Fe_1−xCo_x)₁₄B were determined by field emission energy dispersive spectroscopy compositional analysis of diffusion couple specimens. Various arrangements of component materials and temperatures were examined in order to understand the mechanisms affecting diffusion of the components and to predict the stability of functionally graded microstructures consisting of a dysprosium-rich (Dy_2−yNd_y(Fe_1−xCo_x)₁₄B) outer layer and a neodymium-rich (Nd₂(Fe_1−xCo_x)₁₄B) interior. Estimates of the mutual interdiffusion coefficients of Dy, Nd, Fe, and Co in this system were obtained from the preparation of arc melted and annealed polycrystalline specimens, assuming that the diffusion coefficients were independent of concentration (Grube solution). Fifteen diffusion couples were prepared and heat treated at 1323 K for various times in order to provide data for calculation of the diffusion coefficients. The results indicate that the diffusion coefficients of Fe and Co (D_Fe=3.28×10⁻¹⁰ cm²/s and D_Co=7.63×10⁻¹⁰ cm²/s) were significantly higher at 1323 K in this system than those for Dy and Nd (D_Nd=2.3×10⁻¹² cm²/s and D_Dy=2.9×10⁻¹² cm²/s).     

I. Electron-impact ionization and dissociation of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections for electron-impact ionization and dissociation of C₂H₂⁺ and C₂D₂⁺ have been measured for electron energies ranging from the corresponding thresholds up to 2.5 keV. The animated crossed beams experiment has been used. Light as well as heavy fragment ions that are produced from the ionization and the dissociation of the target have been detected for the first time. The maximum of the cross-section for single ionization is found to be (5.56 ± 0.03)× 10^-17 cm² around 140 eV. Cross-sections for dissociation of C₂ H₂⁺ (C₂D₂⁺) to ionic products are seen to decrease for two orders of magnitude, from C₂D⁺ (12.6 ± 0.3) × 10^-17 cm² over CH⁺(9.55 ± 0.06) × 10^-17 cm², C⁺ (6.66 ± 0.05) × 10^-17 cm², C₂⁺ (5.36 ± 0.27) × 10^-17 cm², H⁺ (4.73 ± 0.29) × 10^-17 cm² and CH₂⁺ (4.56 ± 0.27) × 10^-18 cm² to H₂⁺ (5.68 ± 0.49) × 10^-19 cm². Absolute cross-sections and threshold energies have been compared with the scarce data available in the literature.     

Noise behavior of amorphous GexSi1−xOy for microbolometer applications

High resistivity sputtered a-Ge_xSi_1−xO_y compound was investigated for application to microbolometer fabrication for thermal imaging. Noise behavior of the fabricated bolometers was measured, showing no evidence of random telegraph switching (RTS) noise. 1/f noise was measured at several measuring currents, resulting in a 1/f noise factor of 2.9 × 10⁻¹¹ that can be used for further design and modeling.     

Reactions of hydrazine with the amidogen radical and atomic hydrogen

The rate coefficient k₁ for NH₂ + N₂H₄ was measured to be (5.4 ± 0.4) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ at 296 K. NH₂ was generated by pulsed laser photolysis of NH₃ at 193 nm, and monitored as a function of time by pulsed laser-induced fluorescence excited at 570.3 nm under pseudo-first order conditions in the presence of excess N₂H₄ in an Ar bath gas. This reaction was also investigated computationally, with geometries and scaled frequencies obtained with M06-2X/6-311+G(2df,2p) theory, and single-point energies from CCSD(T)-F12b/cc-pVTZ-F12 theory, plus a term to correct approximately for electron correlation through CCSDT(Q). Three connected transition states are involved and rate constants were obtained via Multistructural Improved Canonical Variational Transition State Theory with Small Curvature Tunneling. Combination of experiment and theory leads to a recommended rate coefficient for hydrogen abstraction of k₁ = 6.3 × 10⁻²³ T^3.44 exp(+289 K/T) cm³ molecule⁻¹ s⁻¹. The minor channel for H + N₂H₄ forming NH₂ + NH₃ was characterized computationally as well, to yield 5.0 × 10⁻¹⁹ T^2.07 exp(-4032 K/T) cm³ molecule⁻¹ s⁻¹. These results are compared to several discordant prior estimates, and are employed in an overall mechanism to compare with measurements of half-lives of hydrazine in a shock tube.     

Absolute cross sections and kinetic energy release distributions for electron-impact ionization and dissociation of CD<Superscript>+</Superscript><Subscript>4</Subscript>

Absolute cross sections for electron-impact dissociative excitation and ionization of CD⁺ ₄ leading to formation of ionic products (CD²⁺ ₄, CD⁺ ₃, CD⁺ ₂, CD⁺, C⁺, D⁺ ₃, D⁺ ₂, and D⁺) have been measured. The animated crossed-beams method is applied in the energy range from the reaction threshold up to 2.5 keV. Around 100 eV, the maximum cross sections are found to be (3.8±0.2) ×10^-19 cm²,  cm², (7.1±0.8) ×10^-17 cm², (9.0±0.8) × 10^-17 cm² and (3.7±0.4) ×10^-17 cm² for the heavy carbonaceous ions CD²⁺ ₄, CD⁺ ₃, CD⁺ ₂, CD⁺ and C⁺ respectively. For the light fragments, D⁺ ₃, D⁺ ₂, and D⁺, the cross sections around the maximum are found to be (5.0±0.6) ×10^-19 cm², (1.7± 0.2) ×10^-17 cm² and (10.6±1.0) ×10^-17 cm², respectively. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. The analysis of ionic product velocity distributions allows determination of the kinetic energy release distributions which are seen to extend from 0 to 9 eV for heavy fragments, and up to 14 eV for light ones. The comparison of present energy thresholds and kinetic energy release with available published data gives information about states contributing to the observed processes. Individual contributions for dissociative excitation and dissociative ionization are determined for each detected product. A complete database including cross sections and energies is compiled for use in fusion application.     

Absolute cross-sections and kinetic-energy-release distributions for electron-impact ionization and dissociation of CD<Stack><Subscript>3</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections have been measured for electron-impact dissociative excitation and ionization of CD₂⁺ leading to formation of CD₂²⁺, CD⁺, C⁺, D₂⁺ and D⁺. The animated crossed-beams method is applied in the energy range from the reaction threshold up to 2.5 keV. The maximum total cross-sections are found to be (1.2±0.1)×10^-17 cm², (6.1±0.7)×10^-17 cm², (6.4±0.7)×10^-17 cm², (26.3±3.8)×10^-19 cm² and (14.9±1.4)×10^-17 cm² for CD₂²⁺, CD⁺, C⁺, D₂⁺ and D⁺ respectively. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product, which are of significant interest in fusion plasma edge modelling and diagnostics. Conforming to the scheme recently applied in the CD₄⁺ and in the CD₃⁺ articles, the cross-sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic-energy-release distributions are determined for each ionic fragment at selected electron energies.     

Detection of gastric slow oscillatory contraction using parasagittal cine MR images: Comparison with simultaneously measured electrogastrogram

PurposeTo determine if parasagittal gastric cine magnetic resonance imaging (MRI) is able to measure gastric oscillatory contractions around 0.05 Hz and to determine its relationship with electrical activity as measured by electrogastrography (EGG).MethodsAssessment of the gastric motility is important for the research of the enteric nervous system and for the diagnosis of functional gastric disorders. Electrogastrography is a non-invasive method that can measure gastric oscillatory electrical activity around 0.05 Hz (slow wave) using electrodes on the abdominal skin, but its sensitivity and specificity of the slow wave detection is limited. We used parasagittal gastric cine MRI around the angular incisure to measure gastric oscillatory contraction around 0.05 Hz in 24 healthy volunteers. Cine MRI was acquired with time resolution of 1 s for 10 min while freely breathing participants were lying on the bed. The gastric area of the cross section was measured for each MR image and assessed its change over time. The results were compared with those for simultaneously recorded EGG.ResultsThe main frequency of the gastric area change for each participant ranged from 0.041 to 0.059 Hz (mean ± S.D. = 0.049 ± 0.004), which corresponds to the gastric slow wave frequency (mean ± S.D. = 0.049 ± 0.004) as measured by EGG (p = 7.9585 × 10 ⁻⁸, Kendall ‘s tau test). Cross correlation analysis showed that 22 of 24 participants’ gastric area changes were significantly (p < 0.05) related to the EGG waveforms. Displacement of the stomach due to respiration did not affect gastric area measurements.ConclusionsParasagittal cine MRI is correlated with EGG recordings and able to detect and quantifying gastric motility abnormalities.