Department of Biomedical Engineering, Wayne State University College of Engineering, Detroit, Michigan, United States of America.
Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan, United States of America.
PLoS One. 2021 Mar 3;16(3):e0247385. doi: 10.1371/journal.pone.0247385. eCollection 2021.
Cervical remodeling is an important component in determining the pathway of parturition; therefore, assessing changes in cervical tissue composition may provide information about the cervix's status beyond the measurement of cervical length. Photoacoustic imaging is a non-invasive ultrasound-based technology that captures acoustic signals emitted by tissue components in response to laser pulses. This optical information allows for the determination of the collagen-to-water ratio (CWR). The purpose of this study was to compare the CWR evaluated by using spectroscopic photoacoustic (sPA) imaging in cervical samples obtained from pregnant and non-pregnant women.
This cross-sectional study comprised cervical biopsies obtained at the time of hysterectomy (n = 8) and at the scheduled cesarean delivery in pregnant women at term who were not in labor (n = 8). The cervical CWR was analyzed using a fiber-optic light-delivery system integrated to an ultrasound probe. The photoacoustic signals were acquired within the range of wavelengths that cover the peak absorption of collagen and water. Differences in the CWR between cervical samples from pregnant and non-pregnant women were analyzed. Hematoxylin and eosin and Sirius Red stains were used to compare the collagen content of cervical samples in these two groups.
Eight cervix samples were obtained after hysterectomy, four from women ≤41 years of age and four from women ≥43 years of age; all cervical samples (n = 8) from pregnant women were obtained after 37 weeks of gestation at the time of cesarean section. The average CWR in cervical tissue samples from pregnant women was 18.7% (SD 7.5%), while in samples from non-pregnant women, it was 55.0% (SD 20.3%). There was a significantly higher CWR in the non-pregnant group compared to the pregnant group with a p-value <0.001. A subgroup analysis that compared the CWR in cervical samples from pregnant women and non-pregnant women ≤41 years of age (mean 46.3%, SD 23.1%) also showed a significantly higher CWR (p <0.01). Lower collagen content in the pregnancy group was confirmed by histological analysis, which revealed the loss of tissue composition, increased water content, and collagen degradation.
The proposed bimodal ultrasound and sPA imaging system can provide information on the biochemical composition of cervical tissue in pregnant and non-pregnant women. Photoacoustic imaging showed a higher collagen content in cervical samples from non-pregnant women as compared to those from pregnant women, which matched with the histological analysis. This novel imaging method envisions a new potential for a sensitive diagnostic tool in the evaluation of cervical tissue composition.
宫颈重塑是决定分娩途径的重要组成部分；因此，评估宫颈组织成分的变化可能提供超出宫颈长度测量的宫颈状态信息。光声成像是一种基于超声的非侵入性技术，它可以捕获组织成分对激光脉冲响应产生的声信号。这种光学信息可以确定胶原与水的比值（CWR）。本研究的目的是比较经阴道超声探头集成光纤光传输系统获得的来自妊娠和非妊娠妇女的宫颈标本的光谱光声（sPA）成像评估的 CWR。
本横断面研究包括因子宫切除术（n=8）和非临产孕妇行择期剖宫产时（n=8）获得的宫颈活检。使用光纤光传输系统对宫颈 CWR 进行分析，该系统集成到超声探头中。光声信号在覆盖胶原和水的峰值吸收波长范围内采集。分析妊娠和非妊娠妇女宫颈标本的 CWR 差异。使用苏木精和伊红以及天狼星红染色比较这两组宫颈标本的胶原含量。
因子宫切除术获得 8 个宫颈标本，年龄≤41 岁 4 个，年龄≥43 岁 4 个；所有因剖宫产在妊娠 37 周时获得的（n=8）宫颈标本均来自孕妇。孕妇宫颈组织样本的平均 CWR 为 18.7%（SD 7.5%），而非妊娠妇女样本为 55.0%（SD 20.3%）。与妊娠组相比，非妊娠组的 CWR 显著升高（p<0.001）。对妊娠和年龄≤41 岁的非妊娠妇女的宫颈标本的 CWR 进行亚组分析，也显示出 CWR 显著升高（p<0.01）。组织学分析证实妊娠组胶原含量较低，表现为组织成分丢失、水含量增加和胶原降解。
所提出的双模态超声和 sPA 成像系统可提供妊娠和非妊娠妇女宫颈组织生物化学组成的信息。光声成像显示非妊娠妇女的宫颈样本胶原含量高于妊娠妇女，与组织学分析结果一致。这种新的成像方法预示着在评估宫颈组织成分方面，一种新的敏感诊断工具具有潜在可能。
