Application of Fourier transform‐second‐harmonic generation imaging to the rat cervix

Abstract

SUMMARY We present the application of Fourier transform-second-harmonic generation (FT-SHG) imaging to evaluate the arrangement of collagen fibers in five non-pregnant rat cervices. Tissue slices from the mid-cervix and near the external orifice of the cervix were analyzed in both two-dimensions (2D) and three-dimensions (3D). We validate that the cervical microstructure can be quantitatively assessed in three dimensions using FT-SHG imaging, and observe collagen fibers oriented both in and out-of-plane in the outermost and the innermost layers, which cannot be observed using 2D FT-SHG analysis alone. This approach has the potential to be a noninvasive method for measuring progressive changes in collagen organization during cervical remodeling in humans.

Development of an Ultrasonic Method to Detect Cervical Remodeling in Vivo in Full-Term Pregnant Women

“…On the other hand, ultrasonic cervical length is a measure at a larger scale, around a couple of centimeters (about 100 times greater than the ultrasonic wavelength). It is not surprising that the attenuation coefficient ranges from 0 to 2.5 dB/cm-MHz; cervical tissue is heterogeneous in nature (Feltovich et al 2010; Lau et al 2013). Thus, to address the heterogeneity issue we averaged all of the attenuation values within the selected portion of the cervix.…”

“…Generally, the shorter the cervix, the greater the probability of preterm birth (Iams and Berghella 2010; Campbell 2011; Romero et al 2013). There has been considerable work by our group (McFarlin et al 2006; Bigelow et al 2008; McFarlin et al 2010; Bigelow et al 2011; Labyed and Bigelow 2011a; Labyed et al 2011; Lau et al 2013; Poellmann et al 2013) and others (House and Socrate 2006; Feltovich et al 2010; Feltovich et al 2012; House et al 2012; Feltovich and Hall 2013; Carlson et al 2014) to develop noninvasive methods to detect and understand cervical microstructural tissue properties associated with cervical remodeling.…”

“…Our research has sought to develop an ultrasonic method that could be correlated with changes associated with cervical remodeling, and potentially associated with preterm birth. We have translated promising basic science ultrasonic methods we used in an animal model (Bigelow et al 2005; Bigelow and O’Brien 2006; McFarlin et al 2006; Bigelow et al 2008; Labyed and Bigelow 2011a; Labyed et al 2011) for use in human pregnancy (McFarlin et al 2006; Bigelow et al 2008; McFarlin et al 2010; Bigelow et al 2011; Labyed and Bigelow 2011a; Labyed et al 2011; Lau et al 2013; Poellmann et al 2013). …”

Using speckle statistics to improve attenuation estimates for cervical assessment

“…In our study of ultrasound attenuation assessment of human cervix tissue, ROI size was varied from 10.5 pulse length to The cervix is mainly composed of collagen with relatively few smooth muscle bundles. The alignment of collagen varies from one layer to another with inner and outer layer having collagen arranged longitudinally, however middle layer has circumferentially aligned collagen [15,41,42]. As the cervix remodels for birth the cervix softens before the cervical length decreases (after 30 weeks of gestation age) which happens along with change of collagen concentration [43].…”

Phase and Texture Characterizations of Scar Collagen Second-Harmonic Generation Images Varied with Scar Duration

“…Thus, it would be advantageous to develop collagen-specific microscopy imaging modalities such as second-harmonic generation (SHG) imaging microscopy for this purpose. Several SHG studies have also explored Fourier transforms for describing collagen (Ambekar et al, 2012;Lau et al, 2013;Adur et al, 2014), but this approach lacks the ability to analyze local features of fibrillar morphology in an image including phase and texture characterization. Despite the success of SHG imaging in elucidating detailed structural differences, it would be desirable to have an objective, quantitative measurement that can identify the state of tissues.…”