Том 47, № 9 (2016)

The polymerization process of the dual cure resin cement AllCem (FGM, Joinvile, Brazil) was investigated theoretically and experimentally. The free radicals responsible for polymerization continuity were characterized by multi-frequency EPR spectroscopy (X-, Q- and W-band) and spectra simulation. It was observed by multifrequency electron paramagnetic resonance spectroscopy and spectra simulation that the paramagnetic species occur simultaneously and independently for both self-cure and photo-cure modes. The paramagnetic species generating the EPR signal are the same for both photo-cure and self-cure polymerization mechanisms.

The objective of the study was to evaluate the clinical significance of diffusion-weighted imaging (DWI) in detecting abdominal metastatic and non-metastatic lymph nodes. We searched for articles about assessing the diagnostic performance of DWI in detecting metastatic and non-metastatic lymph nodes in abdomen in PUBMED until October 2014. A meta-analysis was used to assess the clinical significance of DWI through pooling sensitivity, specificity, calculating likelihood ratios and constructing summary receiver operating characteristics. A total of 1029 patients and 4620 metastatic and non-metastatic lymph nodes were enrolled in the 18 studies. The threshold effect did not exist (Spearman correlation coefficient = 0.084, P = 0.741). The pooled sensitivity and specificity of DWI were 0.82 (95 % CI 0.74–0.89) and 0.90 (95 % CI 0.82–0.94), respectively. The positive likelihood ratio (PLR), negative likelihood ratio (NLR), and area under the curve (AUC) were 6.20 (95 % CI 4.30–8.95), 0.21 (95 % CI 0.11–0.39), and 0.92 (95 % CI 0.90–0.94), respectively. When we defined the pretest probability as 0.25, 0.46, and 0.75, the corresponding post-probability positive (PPP) and post-probability negative (PPN) were 0.73, 0.87, 0.96, and 0.6, 0.14, 0.37. No publication bias was found (bias = −0.69, P = 0.499). Diffusion-weighted imaging may be an expedient tool for detecting abdominal metastatic lymph nodes and non-metastatic lymph nodes. Larger number and high-quality prospective studies still need to be conducted.

Magnetic resonance imaging (MRI) is a medical imaging modality used for high-resolution soft-tissue imaging of human body. In traditional MRI acquisition methods, sampling is performed at Nyquist rate to store data in k-space. The MR image is recovered using inverse Fast Fourier Transform (FFT). This approach results in slow data acquisition process, which is uncomfortable for the patients. Compressed Sensing (CS) acquisition approach offers nearly perfect recovery of MR image using non-linear reconstruction algorithms even from partial k-space data. This study presents a novel method to reconstruct MR image from highly under-sampled data using modified Iterative-Reweighted Least Square (IRLS) method with additional data consistency constraints. IRLS is an effective numerical method used in convex optimization problems. The proposed algorithm was applied on original human brain and Shepp–Logan phantom image, and the data acquired from the MRI scanner at St. Mary’s Hospital, London. The experimental results show that the proposed algorithm outperforms Projection onto Convex Sets (POCS), Separable Surrogate Functional (SSF), Iterative-Reweighted Least Squares (IRLS), Zero Filling (ZF), and Low-Resolution (LR) methods based on the parameters, e.g. Peak Signal-to-Noise Ratio (PSNR), Improved Signal-to-Noise Ratio (ISNR), Fitness, Correlation, Structural SIMilarity (SSIM) index, and Artifact Power (AP).

A specially synthesized nitroxide biradical R₆-¹³C≡C-p-C₆H₄–C≡¹³C-R₆, B3, where R₆ = 1-oxyl-2,2,6,6-tetramethyl-1,2,3,6-tetrahydropyridine nitroxide, has been studied by electron paramagnetic resonance spectroscopy, and electron-nuclear double resonance (ENDOR). Spin density distribution and hyperfine splitting (hfs) constant on ¹³C atoms calculations for biradical B3 were carried out using B3LYP and PBE0 functionals and several different basis sets including N07 family and were compared with the experimental value of the hfs constant on ¹³C atoms, measured from ENDOR spectra of B3. The mechanism of the intramolecular electron spin exchange in B3 biradical is discussed.

The potential of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) to reflect the histological subtype and clinical course in endometrial cancers is not fully elucidated. This study was to evaluate the efficacy of DCE-MRI and DWI in the diagnosis of endometrial carcinoma. Fifty-four patients with endometrial carcinoma were retrospectively studied. DWI and DCE-MRI images were acquired preoperatively in all patients. The depth of myometrial invasion, dynamic enhanced characteristics, time-signal intensity curve and ADC values suggested by preoperative DW/DCE-MRI and the subsequent histopathological findings following the surgery were investigated. The statistical difference was analyzed using SPSS 17.0. Endometrial adenocarcinoma was found in 83.3 % (45/54) cases including 14 cases of highly differentiated (G1), 28 cases of moderately differentiated (G2) and 3 cases of poorly differentiated (G3) according to DWI. There were no statistical difference (P > 0.05) in signal intensity and ADC value of internal obturator muscle among G1, G2 and G3. ADC value between G1 and G2 had statistical difference. Postoperative histopathological examination showed that 79.6 % (43/54) patients were at stage Ia, 16.7 % (9/54) at stage Ib and 3.7 % (2/54) at stage II according to the FIGO 2012 staging criteria. DCE-MRI results showed 74.1 % (40/54) patients were at stage Ia, 14.8 % (8/54) at stage Ib and 3.7 % (2/54) at stage II. Based on the results of histopathological examination, the sensitivity, specificity, accuracy, positive predictive value, negative predictive value of diagnosing endometrial adenocarcinoma la, lb, II by DCE-MRI were 93.0, 88.9, 100 %; 90.9, 93.3, 100 %; 92.6, 92.6, 100 %; 97.6, 72.7, 100 %; 76.9, 97.7, 100 %. The results suggested that DWI and DCE-MRI are helpful in improving the accuracy of the staging and pathological grading of endometrial carcinoma.

In this paper, a new kind of oil cement retarder is prepared by aqueous solution polymerization using acrylamide (AM), 2-methyl-2-acrylic amide propyl sulfonic acid (AMPS) and maleic anhydride (MA) as monomers, and then the polymer PAAM (the acronym of polymer is synthesized by AM, AMPS and MA) was characterized by Fourier transform infrared spectroscopy, the paper also introduced the field performance of this new kind of oil well cement retarder PAAM. Additionally, low field nuclear magnetic resonance (LF-NMR) test technology is employed to test the transverse relaxation time T2 distribution of cement slurry in hydration process, the pure cement slurry C and the cement slurry CHN-1 mixed with polymer PAAM were used as the research object. Finally, combined with the scanning electron microscope (SEM), a further exploration about the retarding mechanism of polymer PAAM was conducted, which shows that mainly reflected in the adsorption, precipitation and complexation effect.