基于MRI与病理对照的骨肉瘤动态增强MRI定量参数与肿瘤微循环及乏氧性表达的相关性研究

目的:基于MRI与病理对照,探讨动态增强MRI(dynamic contrast-enhanced MRI,DCE-MRI)定量参数与骨肉瘤微循环和乏氧性表达的相关性。方法:分析云南省肿瘤医院2019年1月至2020年6月收治的原发于膝关节周围的骨肉瘤患者,手术前行MRI检查。术后取瘤段正中矢状面组织切片,并分割为1 cm×1 cm组织块。检测每个组织块肿瘤坏死率(tumor necrosis rate,TNR)、微血管密度(microvessel density,MVD)、血管内皮生长因子(vascular endothelial growth factor,VEGF)、乏氧诱导因子-1α(hypoxia inducible factor-1α,HIF-1α),并按照Huvos分级标准划分为反应良好组(TNR≥90%)和反应差组(TNR<90%)。在对应位置的DCE-MRI图像上,定位划分与病理样本等感兴趣区,并测量定量参数(Ktrans、Kep、Ve、Vp)。探讨各定量参数与MVD、VEGF、HIF-1α的关系并绘制ROC曲线。结果:入组10例骨肉瘤患者,共取得460个肿瘤病理组织块,其中反应良好组59个(12.8%),反应差组401个(87.2%);VEGF阳性311个(67.6%),阴性149个(32.4%);HIF-1α阳性68个(14.8%),阴性392个(85.2%)。反应良好组Ktrans、Kep、Ve、Vp、MVD计数、VEGF阳性率均高于反应差组,而HIF-1α阳性率低于反应差组(P<0.05)。Ktrans、Kep、Ve与MVD具有相关性,回归系数分别为-0.652、0.525、0.418(P<0.01)。Ve预测VEGF、Kep预测HIF-1α阳性表达的阈值、曲线下面积、敏感性、特异性分别为0.634、0.609、63.7%、60.0%和0.115/min、0.614、42.2%、83.3%。结论:DCEMRI定量参数对骨肉瘤化疗后肿瘤微循环及乏氧性具有一定的评估价值,或可为新辅助化疗疗效评估提供依据。

基于MRI-病理对照的动态增强磁共振成像定量参数评估骨肉瘤新辅助化疗肿瘤坏死率的价值

目的:基于MRI-病理对照,探讨动态增强磁共振成像(dynamic contrast-enhanced magnetic resonance imaging,DCE-MRI)定量参数评估骨肉瘤新辅助化疗(neoadjuvant chemotherapy,NAC)肿瘤坏死率的价值。方法:收集2019年1月至2020年6月于昆明医科大学第三附属医院收治的膝关节周围骨肉瘤患者11例,于NAC前、后行常规MRI及矢状位DCE-MRI检查。NAC疗程结束后两周内经外科手术获取完整肿瘤瘤段,沿正中矢状面剖开,取厚度为5 mm病理切片并分割成大小为1 cm×1 cm的若干组织块,编号后作为与影像对照的病理样本。依靠解剖标志,确定与病理切片对应的DCE-MRI影像层面,将病灶划分为1 cm×1 cm大小感兴趣区(region of interest,ROI),并进行化疗前、后影像ROI与病理样本匹配。采用Omni Kinetics软件测量化疗前定量参数-pre-K^(trans)、pre-K_(ep)、pre-Ve、pre-Vp和化疗后参数-post-K^(trans)、post-K_(ep)、post-V_(e)、post-V_(p),并计算化疗前-后各参数差值∆K^(trans)、∆K_(ep)、∆V_(e)、∆V_(p)。采用Huvos分级标准检测每个病理样本肿瘤坏死率(tumor necrosis rate,TNR),并划分为缓解组(TNR≥90%)和未缓解组(TNR<90%)。采用Mann-Whitney U检验,比较两组病理样本NAC前、后各定量参数是否存在差异。采用ROC曲线,比较NAC后DCE-MRI定量参数及治疗前后的差值预测NAC后TNR的效能。结果:入组骨肉瘤11例,共取得304个病理样本,其中缓解组59个(19.4%),未缓解组245个(80.6%)。两组化疗后K^(trans)、V_(e)、V_(p)均明显降低,且未缓解组参数值明显低于缓解组(P<0.05);化疗后缓解组K_(ep)明显升高(P<0.05),但未缓解组K_(ep)无差异(P>0.05)。两组化疗前后参数差值ΔK^(trans)、ΔV_(e)、ΔV_(p)差异无统计学意义(P>0.05),但缓解组ΔK_(ep)明显低于未缓解组(P<0.05)。ROC曲线分析结果,化疗后定量参数诊断TNR缓解效能优于化疗前-后差值,其中post-K^(trans)诊断效能最高,诊断阈值为0.663/min、AUC为0.745、灵敏度为89.83%、特异性为52.24%。结论:DCE-MRI定量参数在评估骨肉瘤新辅助化疗TNR有一定的应用价值,具有即时、无创反映NAC疗效的应用潜力。

Computed tomography-based radiomics for prediction of neoadjuvant chemotherapy outcomes in locally advanced gastric cancer: A pilot study

Objective: The standard treatment for patients with locally advanced gastric cancer has relied on perioperative radio-chemotherapy or chemotherapy and surgery. The aim of this study was to investigate the wealth of radiomics for pre-treatment computed tomography(CT) in the prediction of the pathological response of locally advanced gastric cancer with preoperative chemotherapy.Methods: Thirty consecutive patients with CT-staged II/III gastric cancer receiving neoadjuvant chemotherapy were enrolled in this study between December 2014 and March 2017. All patients underwent upper abdominal CT during the unenhanced, late arterial phase(AP) and portal venous phase(PP) before the administration of neoadjuvant chemotherapy. In total, 19,985 radiomics features were extracted in the AP and PP for each patient.Four methods were adopted during feature selection and eight methods were used in the process of building the classifier model. Thirty-two combinations of feature selection and classification methods were examined. Receiver operating characteristic(ROC) curves were used to evaluate the capability of each combination of feature selection and classification method to predict a non-good response(non-GR) based on tumor regression grade(TRG).Results: The mean area under the curve(AUC) ranged from 0.194 to 0.621 in the AP, and from 0.455 to 0.722 in the PP, according to different combinations of feature selection and the classification methods. There was only one cross-combination machine-learning method indicating a relatively higher AUC(>0.600) in the AP, while 12 cross-combination machine-learning methods presented relatively higher AUCs(all >0.600) in the PP. The feature selection method adopted by a filter based on linear discriminant analysis + classifier of random forest achieved a significantly prognostic performance in the PP(AUC, 0.722±0.108; accuracy, 0.793; sensitivity, 0.636; specificity,0.889; Z=2.039; P=0.041).Conclusions: It is possible to predict non-GR after neoadjuvant chemotherapy in locally advanced gastric cancers based on the radiomics of CT.

Wave parameters retrieval for dual-polarization C-band synthetic aperture radar using a theoretical-based algorithm under cyclonic conditions

Theoretical-based ocean wave retrieval algorithms are applied by inverting a synthetic aperture radar(SAR)intensity spectrum into a wave spectrum, that has been developed based on a SAR wave mapping mechanism. In our previous studies, it was shown that the wave retrieval algorithm, named the parameterized first-guess spectrum method(PFSM), works for C-band and X-band SAR at low to moderate sea states. In this work, we investigate the performance of the PFSM algorithm when it is applied for dual-polarization c-band sentinel-1(S-1) SAR acquired in extra wide-swath(EW) and interferometric wide-swath(IW) mode under cyclonic conditions.Strong winds are retrieved from six vertical-horizontal(VH) polarization S-1 SAR images using the c-band crosspolarization coupled-parameters ocean(C-3 PO) model and then wave parameters are obtained from the image at the vertical-vertical(VV) polarization channel. significant wave height(SWH) and mean wave period(MWP) are compared with simulations from the WAVEWATCH-III(WW3) model. The validation shows a 0.69 m root mean square error(RMSE) of SWH with a –0.01 m bias and a 0.62 s RMSE of MWP with a –0.17 s bias. Although the PFSM algorithm relies on a good quality SAR spectrum, this study confirms the applicability for wave retrieval from an S-1 SAR image. Moreover, it is found that the retrieved results have less accuracy on the right sector of cyclone eyes where swell directly affects strong wind-sea, while the PFSM algorithm works well on the left and rear sectors of cyclone eyes where the interaction of wind-sea and swell is relatively poor.

Mechanical performance study of the retractable pier column after stiffening

To solve the problem that the overlapping parts of a retractable pier column are prone to damage,this paper proposed the reinforcing measure of setting a stiffener ring at the bottom of the steel pipe.To study how the stiffener-ring parameters influence the mechanical properties of the pier column.12 scale model specimens(including nine specimens with stiffener-ring widths of 40,50,and 60 mm and three unstiffened comparison specimens)were tested under axial compression.Based on the test results,the specimen load-displacement,load-deflection,and load-strain curves were analyzed,and a finite-element model of a pier column under axial compression was established to determine the optimal stiffener size.The results show that setting a stiffener ring enhances the cooperative working ability between the steel pipe and the internal filling material and restrains the lateral deformation of the pier column,thereby improving the ultimate bearing capacity and overall stability of the pier column.The ultimate bearing capacity of the pier column is related to the width and thickness of the stiffener ring.The optimal size of the stiffener ring of the model pier column is 70 mm in width and 4 mm in thickness.The present research results provide a reference for designing compressible pier columns and column stiffening in mines and have important practical significance.

细菌外膜囊泡在脓毒症中的作用机制及应对策略

脓毒症是以全身性炎症反应及多器官功能障碍为特征的一种致命性疾病,革兰氏阴性菌感染是其最常见的病因.外膜囊泡(outer membrane vesicles,OMVs)是革兰氏阴性菌在一定机制作用下,通过细菌外膜膨出、释放的球形囊泡(10-300 nm),其介导细菌-细菌及细菌-宿主相互作用,并提升细菌的生存及致病能力.在脓毒症发生过程中,OMVs作用于多种宿主细胞(如上皮细胞、免疫细胞、血管内皮细胞、血小板等),诱导宿主对感染的免疫应答失控及炎症-凝血正反馈环路,最终导致过激的炎症反应及器官功能障碍.本文简要介绍OMVs的结构组分、分泌机制及生物学功能,重点讨论了OMVs在脓毒症发生中的作用及应对策略(例如利用阳离子抗菌聚合物吸附清除OMVs),旨在为脓毒症的临床防治提供理论基础.

Redox-responsive ferrocene-containing poly(ionic liquid)s for antibacterial applications

Ferrocene(Fc)-containing imidazolium type ionic liquids(ILs) and corresponding poly(ionic liquid)(PIL) membranes with tunable antibacterial activity based on electrochemical redox reaction and host-guest chemistry were developed. The effect of Fc moiety on the antimicrobial activities against both Staphylococcus aureus(S. aureus) and Escherichia coli(E. coli) was studied by minimum inhibitory concentration(MIC). The presence of Fc groups highly enhanced the antibacterial efficiency of Fccontaining ILs because of the generation of reactive oxygen species(ROS). The electrochemical oxidation of Fc to Fc+and the formation of inclusion complexes between Fc and β-CD via host-guest interactions decreased the antibacterial activities of ILs and PIL membranes. The antibacterial activities may be recovered in some extent upon the electrochemical reduction of Fc+to Fc or the exclusion of the Fc out of the cavity of β-CD. Furthermore, all the Fc-containing PIL membranes showed relatively low hemolysis activities and none cytotoxicity toward human cells, indicating clinical feasibility in topical applications.