Diffuse reflectance spectroscopy and imaging for non-invasive objective assessment of genitourinary syndrome of menopause: a pilot study.

The genitourinary symptom of menopause (GSM) affects up to 65% of women, resulting in symptoms such as vulvovaginal dryness, discomfort, and dysuria, which significantly impacts quality of life. The current assessment methods rely on subjective questionnaires that can be influenced by individual differences, as well as invasive measurements that are time-consuming and not easily accessible. In this study, we explore the potential of a non-invasive and objective assessment tool called diffuse reflectance spectroscopy and imaging (DRSI) to evaluate tissue chromophores, including water, lipid, oxyhemoglobin, and deoxyhemoglobin. These measurements provide information about moisture content, lipid levels, oxygen saturation, and blood fraction, which can serve as surrogate markers for genital estrogen levels. Our findings reveal distinct differences in these chromophores among pre, peri, and postmenopausal subjects. By using lipid and blood fraction tissue chromophores in a K-Nearest Neighbour classifier model, we achieved a prediction accuracy of 65% compared to vaginal maturation index (VMI) that is clinically used to assess estrogen-related hormonal changes. When age was included as the third feature, the accuracy increased to 78%. We believe that by refining the study protocol and configuring the fiber probe to examine tissue chromophores both in the superficial vulva skin for epidermal water content and the deeper layers, DRSI has the potential to provide objective diagnosis and aid in monitoring the treatment outcome of GSM.

A Single Sensor Dual-Modality Photoacoustic Fusion Imaging for Compensation of Light Fluence Variation.

OBJECTIVE: A photoacoustic signal is proportional to the product of the optical absorption coefficient and the local light fluence; quantitative photoacoustic measurements of the optical absorption coefficients, therefore, require an accurate compensation of optical fluence variation. Usually, an additional diffuse optical tomography is incorporated to estimate the light fluence variation, but it is often troubled with the bulky measurement system. On this note, we present a dual-modality photoacoustic fusion imaging method that is implemented with a normal photoacoustic imaging (PAI) device. METHODS: A single piezoelectric transducer is employed to receive the photoacoustic waves and passive ultrasound (PU) waves simultaneously. Since the PU wave is generated by the backscattering and diffuse reflection photons, it has the capacity to facilitate diffuse reflectance (DR) imaging. We merged photoacoustic and DR imaging based on their dual-modality with a compensation of the optical fluence variation. RESULTS: The absorption coefficient differences caused by the light fluence variation are reduced more than half with the proposed method, when comparing to the pure photoacoustic imaging. CONCLUSION: The dual-modality photoacoustic fusion imaging is able to correct the PAI errors caused by the optical fluence variation. SIGNIFICANCE: The proposed method can be widely accepted by different PAI applications to compensate the light fluence variations without any additional required element.

Phase-domain photoacoustics eliminating acoustic detection variations.

As one of the fastest-growing imaging modalities in recent years, photoacoustic imaging has attracted tremendous research interest for various applications including anatomical, functional and molecular imaging. Majority of the photoacoustic imaging systems are based on time-domain pulsed photoacoustic method, which utilizes pulsed laser source to induce wideband photoacoustic signal revealing optical absorption contrast. An alternative way is frequency-domain photoacoustic method utilizing chirping modulation of laser intensity to achieve lower system cost. In this paper, we report another way of photoacoustic method, called phase-domain photoacoustic sensing, which explores the phase difference between two consequent intensity-modulated laser pulses induced photoacoustic measurements to reveal the optical property. The basic principle is introduced, modelled and experimentally validated in this paper, which opens another potential pathway to perform photoacoustic sensing and imaging eliminating acoustic detection variations beyond the conventional time-domain and frequency-domain photoacoustic methods.