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.     

Calm1基因敲除小鼠脑蛋白质组学特点及临床意义

目的探究钙调蛋白Calm1基因表达改变对小鼠脑组织蛋白表达谱的影响,挖掘与Calm1有密切靶向关系的功能蛋白及信号通路,并分析Calm1在神经系统疾病中的临床意义。方法PCR产物法初步鉴定小鼠基因型。提取野生型(WT,A组)、Calm1敲除杂合型(HE,B组)、Calm1敲除纯和型(HO,C组)小鼠脑组织的总蛋白,利用TMT标记蛋白质定量技术筛选出差异蛋白质(DEPs),再利用生物信息学技术对DEPs进行注释、富集和分析。结果C-A组脑组织中共鉴别出54个DEPs,其中23个上调,31个下调;C-B组鉴别出35个DEPs,其中19个上调,16个下调。GO分析显示,C-A组及其上调和下调的DEPs分别显著富集到多巴胺生物合成过程、蛋白质折叠和三羧酸代谢过程等条目。C-B组及其上调和下调的DEPs分别显著富集到线粒体内膜、突触结构组成、ATP代谢过程等条目。KEGG分析显示,C-A组及其上调和下调的DEPs分别显著富集到多巴胺能突触、坏死性凋亡、柠檬酸(TCA)循环等通路。C-B组及其上调和下调的DEPs分别显著富到神经退行性变途径-多种疾病、肌萎缩侧索硬化症、帕金森病等通路。STRING分析发现C-A组DEPs“Hsp90ab1”、C-B组DEPs“Cox4i1”关联度最高。结论Calm1敲除后显著改变脑组织中蛋白质表达特征并影响多条与神经退行性疾病关系密切的信号通路,这表明钙调蛋白异常表达在神经系统疾病的发病中起到重要作用。     

Ovine Iliac Vein Model for Endovascular Thrombectomy of Acute Deep Venous Thrombosis

An ovine iliac vein thrombosis model was devised to test a wall-contacting rotational thrombectomy device. Thrombosis was successfully induced in 9 sheep with an average clot length of 31 mm ± 12 and >60% vessel occlusion on angiography. The thrombus was subsequently removed, maintaining normal intraoperative pulmonary arterial pressure (5.9 mm Hg ± 3.6) and complete distal reperfusion after thrombectomy. Additionally, the sheep were without signs of vascular trauma or embolic complications on gross necropsy and histopathologic analysis. The findings from this study support the use of an ovine iliac deep vein thrombosis model for testing of a lower extremity thrombectomy device.     

Comparison of quantitative susceptibility mapping methods on evaluating radiation-induced cerebral microbleeds and basal ganglia at 3T and 7T

Quantitative susceptibility mapping (QSM) has the potential for being a biomarker for various diseases because of its ability to measure tissue susceptibility related to iron deposition, myelin, and hemorrhage from the phase signal of a T₂*-weighted MRI. Despite its promise as a quantitative marker, QSM is faced with many challenges, including its dependence on preprocessing of the raw phase data, the relatively weak tissue signal, and the inherently ill posed relationship between the magnetic dipole and measured phase. The goal of this study was to evaluate the effects of background field removal and dipole inversion algorithms on noise characteristics, image uniformity, and structural contrast for cerebral microbleed (CMB) quantification at both 3T and 7T. We selected four widely used background phase removal and five dipole field inversion algorithms for QSM and applied them to volunteers and patients with CMBs, who were scanned at two different field strengths, with ground truth QSM reference calculated using multiple orientation scans. 7T MRI provided QSM images with lower noise than did 3T MRI. QSIP and VSHARP + iLSQR achieved the highest white matter homogeneity and vein contrast, with QSIP also providing the highest CMB contrast. Compared with ground truth COSMOS QSM images, overall good correlations between susceptibility values of dipole inversion algorithms and the COSMOS reference were observed in basal ganglia regions, with VSHARP + iLSQR achieving the susceptibility values most similar to COSMOS across all regions. This study can provide guidance for selecting the most appropriate QSM processing pipeline based on the application of interest and scanner field strength.     

Long-term Outcomes of Adolescent Anorexia Nervosa on Bone

Purpose

Anorexia nervosa (AN) is a chronic and life-threatening eating disorder that can have a considerable negative impact on the growing skeleton. We hypothesized that the long-term impact on bone health may persist even after normalization of body weight.

程序性死亡受体1和程序性死亡受体配体1在非小细胞肺癌组织中的表达情况及临床意义

目的探讨程序性死亡受体1(PD-1)和程序性死亡受体配体1(PD-L1)在非小细胞肺癌(NSCLC)组织中的表达情况及临床意义。方法选择150例NSCLC患者的NSCLC组织及其癌旁组织,采用实时荧光定量聚合酶链反应(PCR)检测两种组织中PD-1 mRNA和PD-L1 mRNA的相对表达量。采用免疫组织化学染色法检测NSCLC组织中PD-1和PD-L1的表达情况,分析PD-1和PD-L1表达情况与患者临床特征的关系。采用流式细胞术检测NSCLC组织和癌旁组织中CD4^+-PD-1、CD8^+-PD-1、CD14^+-PD-L1、CD68^+-PD-L1的表达水平。结果NSCLC组织中PD-1 mRNA和PD-L1 mRNA的相对表达量分别为(5.03±1.92)和(4.95±1.09),分别高于癌旁组织的(1.72±0.81)和(1.25±0.24),差异均有统计学意义(P﹤0.05)。TNM分期为Ⅲ~Ⅳ期、低分化、有淋巴结转移、有远处转移的NSCLC患者NSCLC组织中PD-1和PD-L1的高表达率均明显高于TNM分期为Ⅰ~Ⅱ期、高+中分化、无淋巴结转移、无远处转移的患者,差异均有统计学意义(P﹤0.01)。NSCLC组织中CD4^+-PD-1、CD8^+-PD-1、CD14^+-PD-L1、CD68^+-PD-L1的表达水平均明显高于癌旁组织,差异均有统计学意义(P﹤0.01)。结论PD-1和PD-L1在NSCLC组织中高表达,可能成为一种新的生物标志物,PD-1/PD-L1信号通路可能参与了NSCLC的免疫逃逸过程,对其逃逸机制进行研究可以为NSCLC患者的临床治疗提供新靶点。     

Derivation of internal dose-based thresholds of toxicological concern for occupational inhalation exposure to systemically acting organic chemicals

This study aimed at deriving occupational thresholds of toxicological concern for inhalation exposure to systemically-acting organic chemicals using predicted internal doses. The latter were also used to evaluate the quantitative relationship between occupational exposure limit and internal dose. Three internal dose measures were identified for investigation: (i) the daily area under the venous blood concentration vs. time curve, (ii) the daily rate of the amount of parent chemical metabolized, and (iii) the maximum venous blood concentration at the end of an 8-hr work shift. A dataset of 276 organic chemicals with 8-hr threshold limit values-time-weighted average was compiled along with their molecular structure and Cramer classes (Class I: low toxicity, Class II: intermediate toxicity, Class III: suggestive of significant toxicity). Using a human physiologically-based pharmacokinetic model, the three identified dose metrics were predicted for an 8-hr occupational inhalation exposure to the threshold limit value for each chemical. Distributional analyses of the predicted dose metrics were performed to identify the percentile values corresponding to the occupational thresholds of toxicological concern. Also, simple linear regression analyses were performed to evaluate the relationship between the 8-hr threshold limit value and each of the predicted dose metrics, respectively. No threshold of toxicological concern could be derived for class II due to few chemicals. Based on the daily rate of the amount of parent chemical metabolized, the proposed internal dose-based occupational thresholds of toxicological concern were 5.61?×?10^?2 and 9?×?10^?4 mmol/d at the 10th percentile level for classes I and III, respectively, while they were 4.55?×?10^?1 and 8.5?×?10^?3 mmol/d at the 25th percentile level. Even though high and significant correlations were observed between the 8-hr threshold limit values and the predicted dose metrics, the one with the rate of the amount of chemical metabolized was remarkable regardless of the Cramer class (r² = 0.81; n = 276). The proposed internal dose-based occupational thresholds of toxicological concern are potentially useful for screening-level assessments as well as prioritization within an integrated occupational risk assessment framework.