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.     

磁共振弥散加权成像结合三维乳腺数字化断层摄影钙化分数在乳腺良恶性钙化病变鉴别中的诊断价值

  目的  评估磁共振弥散加权成像（DWI）结合三维乳腺数字化断层摄影（DBT）钙化分数对于钙化征象在乳腺良恶性病变诊断的应用价值。  方法  回顾性分析我院118例行乳腺DWI检查和DBT检查的患者，DBT检查发现有钙化征象，其中乳腺癌患者51例，病理类型包括:浸润性导管癌、浸润性导管癌、导管原位癌、髓样癌、浸润性小叶癌、黏液腺癌；乳腺良性病变67例，病理类型包括:纤维腺瘤、腺病、导管内乳头状瘤。对所有患者DBT图像的钙化征象进行钙化评分并且测量相应病变区域的表观扩散系数（ADC）值，分析ADC值、钙化分数及二者联合在乳腺含钙化病变的诊断效能。  结果  乳腺癌组ADC值低于乳腺良性病变组，差异有统计学意义（P < 0.05）；钙化分数高于良性病变组，差异有统计学意义（P < 0.05）。ADC值对诊断乳腺良恶性病变的曲线下面积（AUC）为0.853，钙化分数对诊断乳腺良恶性病变的AUC值为0.855，采用Delong检验得出两种方法对诊断乳腺含钙化病变的良恶性诊断效能一致，差异无统计学意义（P=0.625）。两种方法（钙化分数+ADC值）的Logistic回归分析显示，两种方法相结合的AUC值为0.903，具有很高的诊断效能。将ROC曲线（钙化分数、ADC值、两种方法结合的预测概率）经两两Delong检验结果显示，两种方法结合的ROC与单一ROC的差异有统计学意义（P=0.041、0.022）。  结论  DWI与DBT钙化分数对于钙化征象在乳腺良恶性病变的鉴别诊断效能无差别，两种方法相结合的诊断效能显著高于单一方法，为乳腺含钙化病灶的诊断与鉴别诊断中提供了更加可靠的依据。      

从武汉抗疫看中医药文化认同与新的医学模式

从武汉抗疫中医药的投入使用情况,反思现代临床和国人所呈现出的中医药文化认同和就医习惯,探索其历史文化根源及社会因素与医学发展的内在关联。回顾历史,中医屡次临危受命,不负重托,如今大疫当前,中医药再次发挥了重要作用。故新时代探讨如何遵循中医药发展规律,传承精华、守正创新,坚持中医药原创优势,形成中医药学科优势整体化呈现的新模式医学,对提升全社会的中医药认知度具有重要意义。