Compression Optical Coherence Elastography for Assessing Elasticity of the Vaginal Wall under Prolapse after Neodymium Laser Treatment

Abstract

Early stages of pelvic organ prolapses are mainly associated with the pelvic floor disfunction as a result of elasticity changes in the connective tissues including the vaginal wall. In this study, for the first time we used a compression optical coherence elastography (C-OCE) method for assessing elasticity of the vaginal wall under prolapse conditions after intravaginal neodymium (Nd:YAG) laser treatment. C-OCE was used for a comparative ex vivo study of vaginal wall average values of stiffness (elastic Young’s modulus) in patients with age norm (n = 6), stage I–II prolapse (n = 5) without treatment and stage I–II prolapse post 1–2 months Nd:YAG laser treatment (n = 10). To verify the C-OCE data, the structural features of the submucosal connective tissue were identified morphometrically by Van Gieson staining using quantitative textural analysis of the state of collagen bundles. The results of a comparative evaluation of C-OCE and histological images demonstrate a statistically significant tissue stiffness decrease in vaginal wall prolapse compared to the age norm (73.5 ± 18.9 kPa vs. 233.5 ± 48.3 kPa; p < 0.05). This agrees with the histologically revealed increase in the space between the bundles of collagen fibers, which leads to a decrease in the uniformity of their arrangement. After Nd:YAG laser treatment, we observed statistically significant connective tissue stiffness increase compared to vaginal wall prolapse without treatment (152.1 ± 19.2 kPa vs. 73.5 ± 18.9 kPa; p < 0.05), which was associated with an increase in the local thickness of the collagen bundles, a change in their orientation, and an increase in the uniformity of their arrangement. The obtained results indicate that the C-OCE can be a robust method for detecting the early stages of vaginal wall prolapse and assessing the elastic modulus increase in the vaginal wall after laser treatment.

Depth-Resolved Attenuation Mapping of the Vaginal Wall under Prolapse and after Laser Treatment Using Cross-Polarization Optical Coherence Tomography: A Pilot Study

“…It should be noted that CP OCT, in comparison with C-OCE, has greater potential to be used for further, more rapid derivation of 2D or 3D images of the vaginal wall tissue in vivo with higher resolution (~10-15 µm) without additional compression of the tissue and using a reference layer. In addition, compared to our previous C-OCE study [30], the number of study samples was increased, which confirmed our results on the nature of the changes in the collagen bundles in vaginal wall prolapse without and after laser treatment. Our study is also consistent with studies using electron microscopy, in which it was observed that collagen fibrils lost their normal parallel structures in the affected vaginal tissue and also had large gaps between them [52,53].…”

“…In our previous paper [30] describing quantification of changes in the state of collagen bundles localized in the laminae propria of the same studied groups, C-OCE methods and quantitative morphological analysis of the collagen bundles (local thickness, uniformity and orientation) were used. In the case of vaginal wall prolapse, we observed a statistically significant decrease in tissue stiffness and its increase after Nd:YAG laser treatment.…”

“…The laser treatment included two steps: the first one involved treatment of all vaginal walls in a circle with a conical mirror handpiece, and the second one involved targeted treatment of specific vaginal walls (anterior, posterior or lateral, depending on the clinical situation) with a corner mirror handpiece. The laser treatment procedure is described in more detail in [30]. Three laser procedures were performed with an interval of 4-6 weeks.…”

“…A number of studies have demonstrated the initial results of the clinical efficacy of Nd:YAG lasers in gynecology [28][29][30]. The advantages of this type of laser are the noninvasive exposure, the absence of complications and the reduction of the rehabilitation period to 1 week from 1 month following ablative laser exposure.…”

“…The emerging OCT modalities, such as polarization-sensitive (PS) OCT, OCT-angiography and OCT-elastography, as well as endoscopic and handheld scanning probes, significantly extend the prospects and possibilities of the application of OCT techniques to various types of tissues and organs [37][38][39]. More recently, it has been shown that compression optical coherence elastography (C-OCE) can provide a robust method for the detection of the early stages of vaginal wall prolapse based on significant decreases in tissue stiffness of the vaginal wall and can be used for assessing the increase in stiffness of the wall after laser treatment [30].…”