Dual-mode endoscope combines ultrasound and OCT for uterine assessment
Structural problems in the lining of the uterus, called the endometrium, could cause infertility, which unfortunately affects about 10-20% of women worldwide. Scientists from the Shenzhen Institutes of Advanced Technology, the Chinese Academy of Sciences (SIAT-CAS), have developed a diagnostic probe that could offer a less invasive way to determine the nature of endometrial problems behind infertility, as well as help to diagnose other uterine health problems.
The new probe combines ultrasound with optical coherence tomography (OCT) to assess structural features of the endometrium: it has so far been able to differentiate between healthy and injured endometrial tissue in rabbit models based on both surface features and in-depth information such as echo patterns. It is the first successful in vivo demonstration of intrauterine endoscopic imaging in small animals, with a probe measuring just 1.2 mm across.
“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 SIAT-CAS lead scientist Xiaojing Gong. “It also has the potential to detect diseases in the uterus, such as endometrial cancer and uterine fibroids.”
For the new study, the scientists improved upon a previous prototype that combined 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 structural features and 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 improved probe is designed as a simple catheter. A series of tiny optical and ultrasonic components are arranged within the catheter to achieve both ultrasound and OCT mode in high resolution. The catheter additionally has a metal coil to allow for 360-degree full-field rotation once it is inside the uterus.
In testing the probe on rabbits, the scientists were able to evaluate endometrial receptivity due to tissue damage comprehensively and accurately, thanks to the combined information provided by the ultrasonic and OCT modalities. The OCT images showed that healthy endometrial tissues had a smoother surface, while damaged tissues were rougher; and in ultrasound images, the endometrium was found to be thicker in healthy tissues and thinner in areas that had been damaged.
The scientists are working to improve the size, resolution, and imaging range of the probe to make it more practical for clinical use in humans, and plan to increase its ability to discern information about the vascular networks in the uterine lining by adding a photoacoustic mode.
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