Department of Obstetrics and Gynecology, Ludwig Maximilian University Munich, Großhadern Medical Campus, Marchioninistr. 15, 81377, Munich, Germany,
Lasers Med Sci. 2014 Nov;29(6):1821-8. doi: 10.1007/s10103-014-1581-9. Epub 2014 May 15.
Optical coherence tomography (OCT) can be used as an adjunct to colposcopy in the identification of precancerous and cancerous cervical lesions. The purpose of this study was to investigate the effect of acetic acid on OCT imaging. OCT images were taken from unsuspicious and suspicious areas of fresh conization specimens immediately after resection and 3 and 10 min after application of 6 % acetic acid. A corresponding histology was obtained from all sites. The images taken 3 and 10 min after application of acetic acid were compared to the initial images with respect to changes in brightness, contrast, and scanning depth employing a standard nonparametric test of differences of proportions. Further, mean intensity backscattering curves were calculated from all OCT images in the histological groups CIN3, inflammation, or normal epithelium. Mean difference profiles within each of these groups were determined, reflecting the mean differences between the condition before application of acetic acid and the exposure times 3 and 10 min, respectively. According to the null hypothesis, the difference profiles do not differ from profiles fluctuating around zero in a stationary way, which implies that the profiles do not differ significantly from each other. The null hypothesis was tested employing the KPSS test. The visual analysis of 137 OCT images from 46 sites of 10 conization specimens revealed a statistically significant increase in brightness for all three groups and a statistically significant decrease in contrast for normal epithelium after 10 min. Further, an increase in scanning depth was noted for normal epithelium after 10 min and for CIN3 after 3 min. The analysis of mean intensity profiles showed an increased backscattering intensity after application of acetic acid. Acetic acid significantly affects the quality of OCT images. Overall brightness and scanning depth increase with the opposite effect regarding the image contrast. Whether the observed changes facilitate the distinction between dysplastic lesions in a clinical setting needs to be shown in further studies.
光学相干断层扫描（OCT）可作为阴道镜检查的辅助手段，用于识别癌前和宫颈癌变。本研究旨在探讨醋酸对 OCT 成像的影响。在切除后立即以及应用 6%醋酸后 3 和 10 分钟，从新鲜宫颈锥切标本的可疑和无可疑区域采集 OCT 图像。从所有部位获得相应的组织学图像。应用标准的差异比例非参数检验，比较醋酸应用后 3 和 10 分钟采集的图像与初始图像在亮度、对比度和扫描深度方面的变化。此外，从组织学 CIN3 组、炎症组或正常上皮组的所有 OCT 图像中计算平均背向散射强度曲线。确定了这些组内的平均差异曲线，反映了在应用醋酸之前的条件与暴露时间 3 和 10 分钟之间的平均差异。根据零假设，差异曲线没有以稳定的方式偏离零值的波动，这意味着曲线之间没有显著差异。采用 KPSS 检验检验零假设。对来自 10 个宫颈锥切标本 46 个部位的 137 张 OCT 图像进行的视觉分析显示，所有三组的亮度均显著增加，正常上皮的对比度在 10 分钟后显著降低。此外，正常上皮的扫描深度在 10 分钟后增加，CIN3 在 3 分钟后增加。平均强度曲线的分析显示，应用醋酸后背向散射强度增加。醋酸显著影响 OCT 图像的质量。整体亮度和扫描深度增加，而图像对比度则相反。在临床环境中，观察到的变化是否有助于区分发育不良病变，需要在进一步的研究中证明。
