Arterial spin labeling MR image denoising and reconstruction using unsupervised deep learning

Arterial spin labeling (ASL) imaging is a powerful magnetic resonance imaging technique that allows to quantitatively measure blood perfusion non-invasively, which has great potential for assessing tissue viability in various clinical settings. However, the clinical applications of ASL are currently limited by its low signal-to-noise ratio (SNR), limited spatial resolution, and long imaging time. In this work, we propose an unsupervised deep learning-based image denoising and reconstruction framework to improve the SNR and accelerate the imaging speed of high resolution ASL imaging. The unique feature of the proposed framework is that it does not require any prior training pairs but only the subject's own anatomical prior, such as T1-weighted images, as network input. The neural network was trained from scratch in the denoising or reconstruction process, with noisy images or sparely sampled k-space data as training labels. Performance of the proposed method was evaluated using in vivo experiment data obtained from 3 healthy subjects on a 3T MR scanner, using ASL images acquired with 44-min acquisition time as the ground truth. Both qualitative and quantitative analyses demonstrate the superior performance of the proposed txtc framework over the reference methods. In summary, our proposed unsupervised deep learning-based denoising and reconstruction framework can improve the image quality and accelerate the imaging speed of ASL imaging.     

Thrombosis and thromboembolism: Brighton collaboration case definition and guidelines for data collection,analysis, and presentation of immunization safety data

This is a Brighton Collaboration case definition of thrombosis and thromboembolism to be used in the evaluation of adverse events following immunization, and for epidemiologic studies for the assessment of background incidence or hypothesis testing. The case definition was developed by a group of experts convened by the Coalition for Epidemic Preparedness Innovations (CEPI) in the context of active development of SARS-CoV-2 vaccines. The case definition format of the Brighton Collaboration was followed to develop a consensus definition and defined levels of certainty, after an exhaustive review of the literature and expert consultation. The document underwent peer review by the Brighton Collaboration Network and by selected expert reviewers prior to submission.     

Enhancing adherence and management in patients with hypertension: Impact of form and frequency of knowledge intervention

BackgroundThe alarming rise in prevalence of hypertension warrants psychosocial methods supplementing pharmacotherapy for better management and prevention of cardiac emergencies. The objective of the study was to assess the differential impact of the form and frequency of knowledge intervention on management of primary hypertension.Materials and methodThe study was conducted on 256 hypertensive patients recruited through purposive sampling at health centers in Hyderabad, India. Pretest post-test control group quasi-experimental design was adopted for the study. There were two forms of the knowledge intervention, namely ‘Direct Interaction’ and ‘Audio-Visual’. Each form was presented in two frequencies namely ‘single exposure’ and ‘double exposure’. The four groups were labelled as Direct Intervention Single (DIS), Direct Intervention Double (DID), Audio-Visual Single (AVS) and Audio-Visual Double (AVD). Adherence and management of hypertension were assessed at baseline and six weeks post experiment. Analysis of Covariance (ANCOVA) was applied using IBM SPSS Statistics version 20.ResultsANCOVA followed by Bonferroni Multiple Group Comparison Test revealed significant differences between the four intervention groups and control group on adherence (p< .001). In case of hypertension management significant differences were observed between Control group and DIS, DID (p < .001), Control and AVS (p < .01). Control group did not differ from AVD.ConclusionThere was a positive impact of Knowledge Intervention on adherence and management of hypertension. Double exposure in audio visual form was counterproductive in hypertension management.     

MSCT在对比剂外渗的急性腹部创伤性动脉损伤诊断中的应用价值

目的探讨MSCT在对比剂外渗的急性腹部创伤性动脉损伤诊断中的应用价值。方法回顾性分析本院2016年1月～2018年12月收治的44例急性创伤性腹部动脉损伤患者及58例腹部非创伤性动脉病变患者影像资料,分析急性腹部创伤性和非创伤性动脉病变所致对比剂外渗的相关性。结果 44例创伤性腹部损伤患者通过MSCT及图像后处理技术共检出59支动脉损伤,其中对比剂外渗34支、非对比剂外渗共25支;58例急性腹部非创伤组共检出58支动脉病变,其中8支存在对比剂外渗。对比剂外渗征象创伤组出现率明显高于非创伤性组(χ~2=24.42,P0.05)。结论与非创伤组相比,急性腹部创伤性动脉损伤对比剂外渗征象较为常见,MSCT可以较好地显示创伤性对比剂外渗的直接及间接征象。     

欧盟和美国对药品说明书【适应症】项目的撰写要求及启示

介绍欧盟和美国有关药品说明书[适应症]项目撰写的法规和指导原则，特别是最近欧洲药品管理局（EMA）发布的"治疗适应症的用语"。从这些管理文件得到的启示是相关法规规定不宜太粗糙，应具体、精准，应包括内容和格式的规定；而且要有指导原则伴随，以保证法规落到实处。熟悉掌握药品说明书[适应症]项目的撰写要求对规范撰写其他项目有普遍指导意义，对于药品说明书的监管也有裨益。     

Simultaneous multi‐slice spin‐ and gradient‐echo dynamic susceptibility‐contrast perfusion‐weighted MRI of gliomas

Although combined spin‐ and gradient‐echo (SAGE) dynamic susceptibility‐contrast (DSC) MRI can provide perfusion quantification that is sensitive to both macrovessels and microvessels while correcting for T₁‐shortening effects, spatial coverage is often limited in order to maintain a high temporal resolution for DSC quantification. In this work, we combined a SAGE echo‐planar imaging (EPI) sequence with simultaneous multi‐slice (SMS) excitation and blipped controlled aliasing in parallel imaging (blipped CAIPI) at 3 T to achieve both high temporal resolution and whole brain coverage. Two protocols using this sequence with multi‐band (MB) acceleration factors of 2 and 3 were evaluated in 20 patients with treated gliomas to determine the optimal scan parameters for clinical use. ΔR₂*(t) and ΔR₂(t) curves were derived to calculate dynamic signal‐to‐noise ratio (dSNR), ΔR₂*‐ and ΔR₂‐based relative cerebral blood volume (rCBV), and mean vessel diameter (mVD) for each voxel. The resulting SAGE DSC images acquired using MB acceleration of 3 versus 2 appeared visually similar in terms of image distortion and contrast. The difference in the mean dSNR from normal‐appearing white matter (NAWM) and that in the mean dSNR between NAWM and normal‐appearing gray matter were not statistically significant between the two protocols. ΔR₂*‐ and ΔR₂‐rCBV maps and mVD maps provided unique contrast and spatial heterogeneity within tumors.     

相变型纳米粒在动脉血栓的溶栓效果与靶向深度相关性的实验研究

目的 探讨相变型（PT）纳米粒（NPs）靶向动脉血栓深度及其与体外溶栓效果的相关性。方法 通过双乳化法制备一种靶向纤维蛋白的PLGA-PFH-CREKA NPs，验证其理化特性。采集新西兰大白兔的动脉血制作动脉血栓，分别置于荧光标记的靶向PT、非靶向PT、靶向载双蒸水（NPT）的NPs中，并用1 W/cm2声功率密度的低强度聚焦超声（LIFU）辐照，记录前后的质量，计算溶栓率，同时将处理后的血凝块制成切片，通过共聚焦显微镜观察、测量穿透深度，线性回归分析穿透深度与溶栓率的相关性。建立SD大鼠腹主动脉血栓模型，采用靶向PT、非靶向PT NPs评价体内靶向能力。结果 制备的靶向纤维蛋白的PT NPs平均粒径（297.8±11.82）nm，表面电位（1.44±0.22）mV，结构呈均匀球形，分散性好；体外溶栓实验发现靶向PT组与非靶向PT组、NPT组的溶栓率差异有统计学意义（F=108.508，P<0.001）；靶向PT组对血栓的穿透性相较于非靶向PT组、NPT组差异有统计学意义（F=96.187，P<0.001），线性回归发现靶向PT组对血栓穿透深度与溶栓率呈正相关（R2=0.818，P<0.05）。在SD大鼠腹主动脉血栓模型观察到靶向相变组较非靶向相变组对血栓的靶向性更好。 结论 靶向纤维蛋白的相变型NPs，对血栓纤维蛋白有良好的靶向性，有较好的溶栓效果，对血栓有很好的穿透性，并且相变所致溶栓率与血栓穿透深度呈正相关。     

Physiological determinants of residual cerebral arterial pulsatility on best medical treatment after TIA or minor stroke

Cerebral arterial pulsatility is strongly associated with cerebral small vessel disease and lacunar stroke yet its dependence on central versus local haemodynamic processes is unclear. In a population-based study of patients on best medical managment, 4–6 weeks after a TIA or non-disabling stroke, arterial stiffness and aortic systolic, diastolic and pulse pressures were measured (Sphygmocor). Middle cerebral artery peak and trough flow velocities and Gosling’s pulsatility index were measured by transcranial ultrasound. In 981 participants, aortic and cerebral pulsatility rose strongly with age in both sexes, but aortic diastolic pressure fell more with age in men whilst cerebral trough velocity fell more in women. There was no significant association between aortic systolic or diastolic blood pressure with cerebral peak or trough flow velocity but aortic pulse pressure explained 37% of the variance in cerebral arterial pulsatility, before adjustment, whilst 49% of the variance was explained by aortic pulse pressure, arterial stiffness, age, gender and cardiovascular risk factors. Furthermore, arterial stiffness partially mediated the relationship between aortic and cerebral pulsatility. Overall, absolute aortic pressures and cerebral blood flow velocity were poorly correlated but aortic and cerebral pulsatility were strongly related, suggesting a key role for transmission of aortic pulsatility to the brain.     

PA-aO2、PaCO2和Lac水平与急性百草枯中毒患者的预后的相关性

目的探究肺泡-动脉氧分压差(PA-aO2)、动脉血二氧化碳分压(PaCO2)和血乳酸(Lac)水平与急性百草枯中毒(APP)患者的预后的相关性。方法选取2018年8月至2020年8月就诊于本院的126例APP患者,根据3个月随访情况,分为存活组57例和死亡组69例,另选取同期于本院进行健康体检的健康人群45例作为对照组,检测3组PA-aO2、PaCO2和Lac水平。结果与对照组比较,APP患者PA-aO2和Lac水平显著升高,PaCO2水平显著降低,且死亡组变化幅度显著大于存活组,差异有统计学意义(P<0.05);PA-aO2和Lac与存活组呈负相关,与死亡组呈正相关,PaCO2与存活组呈正相关,与死亡组呈负相关(P<0.05);PA-aO2、PaCO2和Lac联合检测对APP患者预后的预测价值显著高于单一指标,差异有统计学意义(P<0.05)。结论PA-aO2、PaCO2和Lac水平与APP患者预后密切相关,值得临床参考。