目的 分析急性阑尾炎及易与之混淆的其他急腹症的CT图像特征，探讨CT检查对急性阑尾炎诊断及鉴别诊断思路的辅助意义。方法 收集2009年6月至2012年6月期间南方医科大学附属小榄医院收治的120例初步诊断为急性阑尾炎患者的CT影像资料，回顾性分析和对比CT征象，研究其与最终诊断之间的内在联系。结果 120例患者中，单纯性阑尾炎15例，化脓性阑尾炎45例，阑尾坏疽、穿孔25例，阑尾脓肿10例；其他急腹症20例；5例未确诊。阑尾炎患者的术前CT征象因阑尾炎种类不同而略有区别，有56例发现粪石；而其他急腹症的CT征象有结肠管壁局限性增厚、肾输尿管高密度影、肾周筋膜增厚、子宫附件区囊性或实性肿物、肠系膜淋巴结肿大、腹水等。结论 CT检查对急性阑尾炎诊断与鉴别诊断思路的形成具有重要的价值。
Repeated measurement quantitative data is a common data type in clinical studies, and is frequently utilized to assess the therapeutic effects of the intervention measures at a single time point in clinical trials. This study clarifies the concepts and calculation methods for sample size estimation of repeated measurement quantitative data, in order to explore the research question of "comparing group differences at a single time point", from three perspectives: the primary research questions in clinical studies, the main statistical analysis methods and the definitions of the primary outcome indicators. Discrepancies in sample sizes calculated by various methods under different correlation coefficients and varying numbers of repeated measurements were examined. The study revealed that the sample size calculation method based on the mixed-effects model or generalized estimating equations accounts for both the correlation coefficient and the number of repeated measurements, resulting in the smallest estimated sample size. Secondly, the sample size calculation method based on covariance analysis considers the correlation coefficient and produces a smaller estimated sample size than the t-test. The t-test based sample size calculation method requires an appropriate approach to be selected according to the definition of the primary outcome measure. The alignment between the sample size calculation method, the statistical analysis method and the definition of the primary outcome measure is essential to avoid the risk of overestimation or underestimation of the required sample size.