• Dual-mode endoscope offers unprecedented

    From ScienceDaily@1:317/3 to All on Monday, April 04, 2022 22:30:44
    Dual-mode endoscope offers unprecedented insights into uterine health
    Ultrasound-OCT probe could help study and diagnose a common cause of infertility

    Date:
    April 4, 2022
    Source:
    Optica
    Summary:
    A new endoscope design that combines ultrasound with optical
    coherence tomography can assess the structural features of the
    endometrium with unprecedented detail. This dual-mode endoscope
    could help doctors diagnose infertility problems that are related
    to endometrial receptivity with greater accuracy than current
    imaging technologies.



    FULL STORY ========================================================================== Researchers have developed a new endoscope that combines ultrasound with optical coherence tomography (OCT) to assess structural features of the
    lining of the uterus, called the endometrium, in unprecedented detail. The
    new probe could one day help doctors diagnose infertility problems that
    are related to endometrial receptivity with greater accuracy than current imaging technologies while reducing the need for invasive biopsies.


    ========================================================================== "This tool combines the two techniques of ultrasound and OCT, allowing
    it to obtain more information and provide a more accurate assessment of endometrial status than traditional vaginal ultrasound," said research
    team leader Xiaojing Gong from the Shenzhen Institutes of Advanced
    Technology of the Chinese Academy of Sciences. "It has the potential to
    be used for basic endometrial research and to further advance clinical assessment of endometrial receptivity and other endometrial-related
    diseases." In the Optica Publishing Group journal Biomedical Optics
    Express, the researchers report the ability for their dual-mode endoscope
    to differentiate between healthy and injured endometrial tissue in rabbit models based on both surface features and depth information. It is the
    first in vivo demonstration of intrauterine endoscopic imaging in small animals, with a probe measuring just 1.2 mm across.

    The endometrium plays a critical role in the ability for a blastocyst to implant in a uterus and grow into a healthy fetus. Failure to implant
    is recognized as a key bottleneck in the reproductive process, with
    impaired endometrial receptivity accounting for about two-thirds of implantation failures.

    By providing detailed structural information about the endometrium,
    the probe could offer a less invasive way to determine if endometrial
    problems are causing infertility, which affects about 10-20% of women worldwide, as well as help to diagnose other uterine health problems.

    "The system can obtain the thickness information of the endometrium,
    the echo pattern of the endometrium and information about damage to the endometrial surface, which play an important role in the evaluation of endometrial receptivity," said Gong. "It also has the potential to detect diseases in the uterus, such as endometrial cancer and uterine fibroids." Creating a better probe


    ==========================================================================
    The current gold standard method for assessing endometrial receptivity
    is through biopsies, which require surgically removing and analyzing
    a small tissue sample. Endoscopic imaging is a less invasive method,
    but current endoscopes can only identify larger defects in the uterus
    such as anatomical malformations or polyps, not assess the structure of
    the endometrium. A vaginal ultrasound can provide information about the thickness of the endometrium and other structural features, but lacks
    the resolution and contrast needed to comprehensively assess endometrial receptivity.

    OCT is an imaging technique that uses relatively long wavelength light (commonly known as near infrared light) to produce high-resolution
    images from within scattering media. It has been adapted for diagnostic
    tools in several medical fields including ophthalmology, cardiology
    and dermatology. Previous studies have shown OCT imaging can be used to identify structural features of the endometrium that are associated with implantation failures.

    For the new study, researchers improved upon a prototype they had
    previously developed to combine OCT and ultrasound imaging in a
    single probe. The OCT modality provides detailed information about
    the superficial endometrium including its surface information, while
    ultrasound provides insights about its full thickness. Since multiple
    features of the endometrium affect implantation success, combining
    these imaging modalities provides a more accurate picture of endometrial receptivity than either mode individually.

    The catheter is designed to pass through the cervix, enter the uterine
    cavity and inject water to facilitate high-resolution imaging. A series
    of tiny custom-designed optical and ultrasonic components are arranged
    within the catheter to achieve both ultrasound and OCT mode. The improved
    probe also uses a single-mode fiber, which offers higher resolution
    and reduced noise for the OCT mode. In addition, the researchers used a
    metal coil to allow the probe to rotate for a 360-degree full-field of
    view once it is inside the uterus.

    "The imaging catheter can realize the rotation and retraction scanning
    through the rotation-retraction unit at the rear end, and obtain the three-dimensional ultrasound-OCT image of the uterus," said Gong.



    ==========================================================================
    A powerful combination To test the endoscope, the researchers used it
    to image the uterine lining of four anesthetized rabbits. Some of the
    rabbits were healthy while others had undergone a procedure to wash the endometrium with ethanol for different lengths of time, damaging the
    tissue to varying degrees.

    The researchers quantified features of the endometrium including its
    thickness, distribution and surface roughness separately in ultrasonic
    and OCT modalities.

    The OCT images showed that healthy endometrial tissues had a smoother
    and more continuous surface, while damaged tissues were more rough. In ultrasound images, the endometrium was found to be thicker in healthy
    tissues and thinner in areas that had been damaged. While each modality provided valuable information on its own, it wasn't until the researchers combined the information from each that they were able to comprehensively
    and accurately evaluate the degree of tissue injury.

    "These results demonstrated the importance of bimodality in the detection
    of the extent of endometrial damage," said Gong. "The variance is too
    large, and it is difficult to distinguish the degree of injury through
    a single mode of information. However, combining the information of the
    two modalities can differentiate the degree of damage." The probe also provided echo patterns that were similar to what can be obtained with
    vaginal ultrasound but with better resolution. In addition, the images
    revealed physical features such as polyp-like formations as small as 200 microns, demonstrating the probe's ability to discern tiny lesions that
    could affect endometrial health.

    The researchers plan to add a photoacoustic mode to increase the probe's ability to observe blood flow and information about the vascular networks
    in the uterine lining. In addition, they are working to improve the size, resolution and imaging range of the imaging catheter to make it more
    practical for clinical use in humans.


    ========================================================================== Story Source: Materials provided by Optica. Note: Content may be edited
    for style and length.


    ========================================================================== Journal Reference:
    1. Jinke Zhang, Meng Du, JInghui Fang, Shengmiao Lv, Wenjin Lou,
    Zhihua Xie,
    Zhiyi Chen, Xiaojing Gong. In vivo evaluation of endometrium through
    dual-modality intrauterine endoscopy. Biomedical Optics Express,
    2022; 13 (5): 2554 DOI: 10.1364/BOE.453191 ==========================================================================

    Link to news story: https://www.sciencedaily.com/releases/2022/04/220404120522.htm

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