A Priori Subcell Limiting Approach for the FR/CPR Method on Unstructured Meshes

A priori subcell limiting approach is developed for high-order flux reconstruction/correction procedure via reconstruction (FR/CPR) methods on two-dimensional unstructured quadrilateral meshes. Firstly, a modified indicator based on modal energy coefficients is proposed to detect troubled cells, where discontinuities exist. Then, troubled cells are decomposed into nonuniform subcells and each subcell has one solution point. A second-order finite difference shock-capturing scheme based on nonuniform nonlinear weighted (NNW) interpolation is constructed to perform the calculation on troubled cells while smooth cells are calculated by the CPR method. Numerical investigations show that the proposed subcell limiting strategy on unstructured quadrilateral meshes is robust in shock-capturing.     

衰减伪影对冠心病患者门控心肌灌注显像图像质量及灌注结果的影响

目的探讨衰减伪影对冠心病患者门控心肌灌注显像(GMPI)图像质量及灌注结果的影响。资料与方法回顾性分析2020年3月—2021年3月在郑州大学第一附属医院核医学科经冠状动脉造影证实且于造影前后1周行GMPI的99例冠心病患者的图像,定性及半定量分析衰减校正前后GMPI图像结果,比较衰减校正前后左心室各壁段平均放射性计数及灌注结果的差异,进一步分析衰减校正前后灌注结果不一致部分的受检者的节段性室壁运动及增厚情况。结果与衰减校正前比较,衰减校正后左心室间隔、下后壁及侧壁的平均放射性计数较高(Z=-7.302、-8.014、-3.991,P均<0.001),心尖部较低(Z=-8.021,P<0.001)。其中女性衰减校正后前壁平均放射性计数减低(Z=-2.314,P=0.021)。男性衰减校正前后下后壁放射性计数差值明显高于女性(t=-8.408,P<0.05)。衰减校正后44%(44/99)的左前降支及37%(37/99)的右冠状动脉分支供血区域显像结果发生改变,结合超声心动图及GMPI结果显示其中85%(35/41)的左前降支及81%(29/36)的右冠状动脉分支供血区域室壁运动及室壁增厚率均正常。结论衰减伪影对GMPI的图像质量和灌注结果有较大影响,结合室壁运动和增厚情况等有助于鉴别衰减伪影,提高诊断准确度与特异度。     

Impact of sampling rate on statistical significance for single subject fMRI connectivity analysis

A typical time series in functional magnetic resonance imaging (fMRI) exhibits autocorrelation, that is, the samples of the time series are dependent. In addition, temporal filtering, one of the crucial steps in preprocessing of functional magnetic resonance images, induces its own autocorrelation. While performing connectivity analysis in fMRI, the impact of the autocorrelation is largely ignored. Recently, autocorrelation has been addressed by variance correction approaches, which are sensitive to the sampling rate. In this article, we aim to investigate the impact of the sampling rate on the variance correction approaches. Toward this end, we first derived a generalized expression for the variance of the sample Pearson correlation coefficient (SPCC) in terms of the sampling rate and the filter cutoff frequency, in addition to the autocorrelation and cross‐covariance functions of the time series. Through simulations, we illustrated the importance of the variance correction for a fixed sampling rate. Using the real resting state fMRI data sets, we demonstrated that the data sets with higher sampling rates were more prone to false positives, in agreement with the existing empirical reports. We further demonstrated with single subject results that for the data sets with higher sampling rates, the variance correction strategy restored the integrity of true connectivity.     

Posterior thoracolumbar fusion in a patient with Kleefstra Syndrome related scoliosis: The first case reported

Spine deformities could be considered a possible manifestation of the childhood hypotonia, typical feature of Kleefstra Syndrome (KS). There is a paucity of literature describing posterior spinal fusion in the Kleefstra syndrome patient. For patients who develop severe scoliotic curve, bracing is often ineffective and surgery is recommended. We report the first corrective surgery for scoliosis in one patient with KS.We describe a case of 13-year-old female with severe developmental scoliosis in KS. Preoperative examination showed a thoracolumbar scoliosis with left convex thoracic curve (T3-T9, 97°) and right convex thoracolumbar curve (T9-L3, 88°). Posterior correction, pedicle screw fixation and bone graft fusion T3-L5 was performed. Postoperatively, the thoracic curve was corrected to 33° while the thoracolumbar one to 26° and better standing posture was obtained. Six month follow-up images showed no loosening of the hardware. The patient is still in our follow-up program.Scoliosis seems to be a rare evenience of the severe hypotonia of patients with KS. We report the first case of scoliosis in KS treated successfully with surgery. Corrective surgery for spinal deformity, such as scoliosis, could help in posture and improve the quality of life especially in complicated patients such as syndromic ones.     

我国中药材产地市场整合研究——以金银花、枸杞子、板蓝根和太子参为例

中药材专业市场交易量逐渐下降,产地市场交易成为趋势。研究产地市场整合程度有利于了解中药材市场的运行情况,对于合理规划中药材生产和提高市场效率具有重要意义。选取大宗中药材金银花、枸杞子、板蓝根和太子参研究中药材市场整合程度,利用2013—2019年价格指数,运用协整检验、误差修正模型和格兰杰因果检验进行实证分析。结果表明,我国中药材产地市场长期整合程度较高;中药材产地市场的短期整合程度远不及长期整合程度。为此提出4点政策建议:完善中药材价格信息平台、打造非道地产区中药材优质品牌、加快建成中药材质量追溯体系和建设中药材现代物流体系。     

微型种植体支抗与口外弓支抗对安氏Ⅱ类1分类错牙合畸形患者的矫治效果对比分析

目的:分析比较微型种植体支抗与口外弓支抗对安氏Ⅱ类1分类错牙合畸形患者的矫治效果。方法:收集笔者医院95例安氏Ⅱ类1分类错牙合畸形患者临床资料,根据其治疗方法将之分为口外弓支抗(MIA组)46例和微型种植体支抗组(HGA组)49例,比较其矫正前后头影测量结果和模型测量结果,矫治时间和不良反应。结果:治疗后,MIA组牙合平面与SN平面夹角(OP-SN)、上颌中切牙牙长轴与SN平面夹角(U1-SN)、上唇突度、下唇突度、上唇最凸点至E线垂直距离(E line-UL)、下唇最凸点至E线垂直距离(E line-LL)、覆牙合(OB)、覆盖(OJ)均小于HGA组(P<0.05),矫治时间短于HGA组(P<0.05),总不良反应发生率与HGA组差异无统计学意义(P>0.05)。结论:对比HGA,MIA对安氏Ⅱ类1分类错牙合畸形患者的矫治效果更佳,且能够缩短矫治时间。     

Improved prediction of brain age using multimodal neuroimaging data

Brain age prediction based on imaging data and machine learning (ML) methods has great potential to provide insights into the development of cognition and mental disorders. Though different ML models have been proposed, a systematic comparison of ML models in combination with imaging features derived from different modalities is still needed. In this study, we evaluate the prediction performance of 36 combinations of imaging features and ML models including deep learning. We utilize single and multimodal brain imaging data including MRI, DTI, and rs‐fMRI from a large data set with 839 subjects. Our study is a follow‐up to the initial work (Liang et al., 2019. Human Brain Mapping) to investigate different analytic strategies to combine data from MRI, DTI, and rs‐fMRI with the goal to improve brain age prediction accuracy. Additionally, the traditional approach to predicting the brain age gap has been shown to have a systematic bias. The potential nonlinear relationship between the brain age gap and chronological age has not been thoroughly tested. Here we propose a new method to correct the systematic bias of brain age gap by taking gender, chronological age, and their interactions into consideration. As the true brain age is unknown and may deviate from chronological age, we further examine whether various levels of behavioral performance across subjects predict their brain age estimated from neuroimaging data. This is an important step to quantify the practical implication of brain age prediction. Our findings are helpful to advance the practice of optimizing different analytic methodologies in brain age prediction.