胎心率与宫缩描记图的计算机数码转换

Computerized Transformation of the Cardiotocographic Paper Record to Its Digital Equivalent for Computerised Analysis

目的建立胎心率与宫缩描记图的计算机数码转换方法。方法采用平台扫描器，摄取４０例胎儿的胎心率与宫缩描记图，将扫描成像先进行倾斜校正，然后利用对比增强法，去除记录纸上原有的格子背景和手写的注解，仅留下胎心率和宫缩压力曲线，进行数码转换。通过比较实时的记录和以本方法转换的胎心率数值的差异进行方法学鉴定。结果实时记录与推算值的平均差异为－０２６～－１２６次，其９５％可信限值为－７～５次。结论使用本方法可以有效地将许多贮存的胎心率与宫缩描记图进行数码转换，以便进一步进行回顾性计算机分析研究，为研制高精度的计算机化胎儿预测系统，提供极有价值的资料。

Objective To analyze cardiotocograph by computer, the tracings recorded in paper form must first be converted into their digital equivalent. We developed a method by which this process may be performed. Methods Paper recordings were first scanned using a conventional flat bed scanner to obtain a digital image. Each image was firstly corrected for rotational misalignment error during scanning and, sceondly the grid was removed by performing logistic contrast enhancement to leave the discrete fetal heart rate and tocographic tracings. The method was validated by comparing differences between the fetal heart rate obtained from the paper record with that directly obtained from the fetal monitor. Results Forty recordings were analyzed. The mean difference per recording between the actual and derived values ranged from -0.26～-1.26 beats per minute. The 95% confidence interval for the pooled differences between the derived and actual fetal heart rate values was -7～5 beats per minute. Conclusion By using the techniques described in this paper, it is now possible to convert the large number of paper records available so that they can be analyzed by computerized cardiotocograph interpreters.