Vaginal tactile imaging

In vivo measurement of the elastic properties of pelvic floor muscles in pregnancy using shear wave elastography

OBJECTIVE

We aimed to investigate changes in the elastic properties of levator ani muscle (LAM) and external anal sphincter (EAS) during pregnancy using shear wave elastography (SWE). Our secondary objective was to examine the association between the elastic properties of pelvic floor muscles (PFM) and perineal tears at childbirth.

METHODS

This was a prospective monocentric study, including nulliparous women. Three visits were planned (14-18, 24-28, and 34-38 weeks) with a SWE assessment of the LAM and EAS at rest and during Valsalva maneuver. Then, we collected data about the delivery's characteristics. Assessments were performed using an Aixplorer V12® device (SL 18-5 linear probe) using a transperineal approach, reporting the shear modulus in kPa. We looked for changes in PFM's elastic properties during pregnancy using one-way ANOVA for repeated measures. We compared the mean shear modulus in late pregnancy for each muscle and condition between women with an intact perineum at delivery and those with a perineal tear using Student's t test.

RESULTS

Forty-seven women were considered. Forty-five women had vaginal delivery of which 38 (84.4%) had perineal tears. We did not report any significant changes in the elastic properties of PFM during pregnancy. Women with an intact perineum at delivery had a stiffer EAS at Valsalva maneuver in late pregnancy (27.0 kPa vs. 18.2 kPa; p < 0.005).

CONCLUSIONS

There were no significant changes in the elastic properties of the PFM in pregnancy. Stiffer EAS in late pregnancy appears to be associated with a lower incidence of perineal tears.

The Application of Shear Wave Elastography to Determine the Elasticity of the Levator Ani Muscle and Vaginal Tissue in Patients With Pelvic Organ Prolapse

OBJECTIVES

The changes of the extracellular matrix of the connective tissue have significantly contributed to the incidence of pelvic organ prolapse (POP). It seems reasonable that sonoelastography could be a useful tool to evaluate the elasticity of pelvic floor tissue in patients with POP and compare it to those without POP. The main aim of this pilot study was to determine if there are differences in the elasticity of the levator ani muscle (LAM) and vaginal tissue between patients with and without POP.

METHODS

Prospective observation study, including 60 patients (30 with POP and 30 without POP). Sonoelastography was performed to evaluate the elasticity (in kilopascals, kPa) of the following regions of interest: vagina at the level of middle third of the urethra; vagina at the level of the bladder trigone; vagina in the anterior and posterior fornix; vagina at the level of middle third of the anorectal canal; posterior third of the LAM.

RESULTS

A total of 60 patients completed the study (30 with POP, 30 without POP). In the POP group, 18/30 (60%) had an anterior vaginal wall prolapse, 3/30 (10%) a uterine prolapse, 15/30 (50%) a rectocele, and 6/30 (20%) a enterocele. Patients with POP had higher elasticity in all anatomical study areas, with statistically significant differences in the anterior fornix (13.6 vs 11.2 kPa; P: .012). A multiple regression (controlling age, menopausal stage, and parity) allowed to detect statistically significant differences in the elasticity of the middle third of the urethra (P: .03) and the middle third of the anorectal canal (P: .019).

CONCLUSION

It is possible to evaluate the elasticity of the LAM and vaginal tissue using sonoelastography, detecting a higher elasticity in patients with POP than in those without POP.

Transparent Pneumatic Tactile Sensors for Soft Biomedical Robotics

Palpation is a simple but effective method to distinguish tumors from healthy tissues. The development of miniaturized tactile sensors embedded on endoscopic or robotic devices is key to achieving precise palpation diagnosis and subsequent timely treatment. This paper reports on the fabrication and characterization of a novel tactile sensor with mechanical flexibility and optical transparency that can be easily mounted on soft surgical endoscopes and robotics. By utilizing the pneumatic sensing mechanism, the sensor offers a high sensitivity of 1.25 mbar and negligible hysteresis, enabling the detection of phantom tissues with different stiffnesses ranging from 0 to 2.5 MPa. Our configuration, combining pneumatic sensing and hydraulic actuating, also eliminates electrical wiring from the functional elements located at the robot end-effector, thereby enhancing the system safety. The optical transparency path in the sensors together with its mechanical sensing capability open interesting possibilities in the early detection of solid tumor as well as in the development of all-in-one soft surgical robots that can perform visual/mechanical feedback and optical therapy.

Non-Invasive Radial Artery Blood Pressure Monitoring Using Error Compensated Tactile Sensors and Patient Specific Oscillometry

This paper presents a new method of measuring non-invasive blood pressure at the radial artery based on oscillometry and tonometry. A localized capacitive tactile sensor array is used with a novel algorithm based on waveform features for optimizing oscillometry ratios. A novel tonometer is presented with typically 1% base measurement error, with sensor errors compensated using a custom error model, and applied to blood pressure measurement at the radial artery. The tonometer gives a direct arterial waveform, and uses a manual pressure sweep to determine blood pressure. Key points on the oscillogram are correlated with optimal ratios for minimizing mean errors and standard deviation for an individual. This paper details an initial assessment into the dominant sources of error, for the purpose of determining feasibility and directing future research. Over a limited clinical trial of N_p = 20, No = 180, the reported BP accuracy is MAE = 0.61/0.38mmHg and 1SD = 7.14/5.91mmHg for systolic and diastolic measurements respectively. The average load on the patient is in the order of 5N, compared with around 1000N for a brachial cuff, which represents a clear improvement in patient comfort. This is a positive result, indicating larger scale performance within AAMI and BHS standards, and stands as a useful benchmark for further development of the system into a clinical product for rapid and comfortable BP measurement. Clinical Relevance This paper demonstrated that direct tonometry can measure blood pressure if sensor error is compensated by the designer. This method uses 200x less load than conventional cuffs suitable for long term and supine use.

The ThermiVa In Genital Hiatus Treatment (TIGHT) Study

INTRODUCTION

Vaginal laxity or the sensation of vaginal looseness affects anywhere from 24% to 50% of postpartum women.

AIM

To evaluate the efficacy and safety of the ThermiVa (ThermiAesthetics, TX, USA) monopolar radiofrequency device in the treatment of vulvovaginal laxity and sexual dysfunction METHODS: The TIGHT study was a prospective single blinded randomized sham-control trial conducted over 3 sites in Australia and India. The study included parous woman over the age of 18 who complained of vaginal laxity/looseness. Participants were randomized into a treatment group and a sham group. Patients in the treatment group were treated with an active probe, whereas, women in the placebo group were treated with sham probes that only reached subtherapeutic temperatures.

MAIN OUTCOME MEASURES

Subjective success was determined by improvement in the Female Sexual Function Index (FSFI), Vaginal Laxity Questionnaire (VLQ), Vaginal Flatus Score (VFS), and the Vaginal laxity Bother Score (VLBS). Objective success was measured via the Modified Oxford Score (MOS) and Genital Hiatus (GH) length.

RESULTS

Sixty-three participants were recruited (sham n = 29, treatment n = 34). In the treatment group, FSFI scores improved at 3 months (mean difference 8-points, P value .02), and at 6 months (mean difference 5-points, P value .07). At baseline 89.7% and 87.2% of patients in the sham and treatment groups, respectively, classified themselves as "loose" on the VLQ. At 6 months 73.1% of patients in the sham group still identified as "loose" compared to 32.4% of patients in the active group (P value .01). Subjective success was also noted in the VLBS (P value .02). Results pertaining to VLFS, MOS, and GH did not reveal statistically significant results.

CONCLUSION

Treatment with ThermiVa was associated with a modest subjective improvement in vaginal laxity and sexual dysfunction and proved to be safe over the 6-month trial period. Pather K, Dilgir S, Rane A. The ThermiVa In Genital Hiatus Treatment (TIGHT) Study. Sex Med 2021;XX:XXXXXX.

3D Ultrasound Strain Imaging of Puborectalis Muscle

The female pelvic floor (PF) muscles provide support to the pelvic organs. During delivery, some of these muscles have to stretch up to three times their original length to allow passage of the baby, leading frequently to damage and consequently later-life PF dysfunction (PFD). Three-dimensional (3D) ultrasound (US) imaging can be used to image these muscles and to diagnose the damage by assessing quantitative, geometric and functional information of the muscles through strain imaging. In this study we developed 3D US strain imaging of the PF muscles and explored its application to the puborectalis muscle (PRM), which is one of the major PF muscles.

Predictive Value of Biomechanical Mapping for Pelvic Organ Prolapse Surgery

OBJECTIVE

This study examined biomechanical changes in pelvic floor after urogynecological surgery.

METHODS

This multisite clinical study was designed to explore changes in tissue elasticity, pelvic support, and certain functions (contractive strength, muscle relaxation speed, muscle motility) after pelvic organ prolapse (POP) surgery. A biomechanical mapping of the pelvic floor was performed before and 4 to 6 months after the surgery. The biomechanical data for 52 parameters were acquired by vaginal tactile imaging for manually applied deflection pressures to vaginal walls and pelvic muscle contractions. The two-sample t-test (P < 0.05) was used to test the null hypothesis that presurgery data in group 1 (positive parameter change after surgery) and presurgery data in group 2 (negative parameter change after surgery) belonged to the same distribution.

RESULTS

A total of 78 subjects with 255 surgical procedures were analyzed across 5 participating clinical sites. All 52 t-tests for group 1 versus group 2 had P value in the range from 4.0 × 10-10 to 4.3 × 10-2 associating all of the 52 parameter changes after surgery with the presurgical conditions. The P value of before and after surgery correlation ranged from 3.7 × 10-18 to 1.6 × 10-2 for 50 of 52 tests, with Pearson correlation coefficient ranging from -0.79 to -0.27. Thus, vaginal tactile imaging parameters strongly correlated weak pelvic floor presurgery with the positive POP surgery outcome of improved biomechanical properties.

CONCLUSIONS

Pelvic organ prolapse surgery, in general, improves the biomechanical conditions and integrity of the weak pelvic floor. The proposed biomechanical parameters can predict changes resulting from POP surgery.

In vivo assessment of the elastic properties of women's pelvic floor during pregnancy using shear wave elastography: design and protocol of the ELASTOPELV study

Background

Animal studies have reported an increase in pelvic floor muscle stiffness during pregnancy, which might be a protective process against perineal trauma at delivery. Our main objective is to describe the changes in the elastic properties of the pelvic floor muscles (levator ani, external anal sphincter) during human pregnancy using shear wave elastography (SWE) technology. Secondary objectives are as follows: i) to look for specific changes of the pelvic floor muscles compared to peripheral muscles; ii) to determine whether an association between the elastic properties of the levator ani and perineal clinical and B-mode ultrasound measures exists; and iii) to provide explorative data about an association between pelvic floor muscle characteristics and the risk of perineal tears.

Methods

Our prospective monocentric study will involve three visits (14–18, 24–28, and 34–38 weeks of pregnancy) and include nulliparous women older than 18 years, with a normal pregnancy and a body mass index (BMI) lower than 35 kg.m^− 2. Each visit will consist of a clinical pelvic floor assessment (using the Pelvic Organ Prolapse Quantification system), an ultrasound perineal measure of the anteroposterior hiatal diameter and SWE assessment of the levator ani and the external anal sphincter muscles (at rest, during the Valsalva maneuver and during pelvic floor contraction), and SWE assessment of both the biceps brachii and the gastrocnemius medialis (at rest, extension and contraction). We will collect data about the mode of delivery and the occurrence of perineal tears. We will investigate changes in continuous variables collected using the Friedman test. We will look for an association between the elastic properties of the levator ani muscle and clinical / ultrasound measures using a Spearman test at each trimester. We will investigate the association between the elastic properties of the pelvic floor muscles and perineal tear occurrence using a multivariate analysis with logistic regression.

Discussion

This study will provide original in vivo human data about the biomechanical changes of pregnant women’s pelvic floor. The results may lead to an individualized risk assessment of perineal trauma at childbirth.

Trial registration

This study was registered on https://clinicaltrials.gov on July 26, 2018 (NCT03602196).

Cervical Characterization with Tactile-Ultrasound Probe

BACKGROUND

Premature cervical softening and shortening may be considered an early mechanical failure that predisposes to preterm birth. Preliminary clinical studies demonstrate that cervical elastography may be able to quantify this phenomenon and predict spontaneous preterm delivery.

OBJECTIVE

To explore a new approach for cervix elasticity and length measurements with tactile-ultrasound probe.

METHODS

Cervix probe has tactile array and ultrasound transducer designed to apply controllable load to cervix and acquire stress-strain data for calculation of cervical elasticity (Young's modulus) and cervical length for four cervix sectors. Average values, standard deviations, intraclass correlation coefficients and the 95% limits of agreement (Bland-Altman plots) were estimated.

RESULTS

Ten non-pregnant and ten pregnant women were examined with the probe. The study with non-pregnant women demonstrated a reliable acquisition of the tactile signals. The ultrasound signals had a prolonged appearance; identification of the internal os of the cervix in these signals was not reliable. The study with pregnant women with the gestational age of 25.4 ± 2.3 weeks demonstrated reliable data acquisition with real-time visualization of the ultrasound signals. Average values for cervical elasticity and standard deviations of 19.7 ± 15.4 kPa and length of 30.7 ± 6.6 mm were calculated based on two measurements per 4 sectors. Measurement repeatability calculated as intraclass correlation coefficients between two measurements at the same cervix sector on pregnant women was found to be 0.97 for cervical elasticity and 0.93 for the cervical length. The 95% limits of agreement of 1) cervical elasticity were from -22.4% to +14.9%, and 2) cervical length from -13.3% to +16.5%.

CONCLUSIONS

This study demonstrated clinically acceptable measurement performance and reproducibility. The availability of stress-strain data allowed the computation of cervical elasticity and length. This approach has the potential to provide cervical markers to predict spontaneous preterm delivery.

A fiber-optic sensor-based device for the measurement of vaginal integrity in women

AIMS

Pelvic floor disorders (PFDs) in women are a major public health concern. Current clinical methods for assessing PFDs are either subjective or confounded by interference from intra-abdominal pressure (IAP). This study introduces an intravaginal probe that can determine distributed vaginal pressure during voluntary exercises and measures the degree of vaginal tissue support independent of IAP fluctuations.

METHODS

An intravaginal probe was fabricated with 18 independent fiber-optic pressure transducers positioned along its upper and lower blades. Continuous pressure measurement along the anterior and posterior vaginal walls during the automated expansion of the probe enabled the resistance of the tissue to be evaluated as a function of displacement, in a manner reflecting the elastic modulus of the tissue. After validation in a simulated vaginal phantom, in vivo measurements were conducted in the relaxed state and during a series of voluntary exercises to gauge the utility of the device in women.

RESULTS

The probe reliably detected variations in the composition of sub-surface material in the vaginal phantom. During in-vivo measurements the probe detected distributed tissue elasticity in the absence of IAP change. In addition, the distribution of pressure along both anterior and posterior vaginal walls during cough, Valsalva and pelvic floor contraction was clearly resolved with a large variation observed between subjects.

CONCLUSIONS

Our data highlight the potential for the probe to assess the integrity of the vagina wall and support structures as an integrated functional unit. Further in vivo trials are needed to correlate data with clinical findings to assist in the assessment of PFDs.

Biomechanical mapping of the female pelvic floor: changes with age, parity and weight

Quantitative biomechanical characterization of pelvic supportive structures and functions in vivo is thought to provide insight into the pathophysiology of pelvic floor disorders including pelvic organ prolapse (POP). An innovative approach - vaginal tactile imaging - allows biomechanical mapping of the female pelvic floor to quantify tissue elasticity, pelvic support, and pelvic muscle functions. The objective of this study is to explore an extended set of 52 biomechanical parameters to characterize pelvic floor changes with age, parity, and subject weight for normal pelvic floor conditions. 42 subjects with normal pelvic conditions (no POP, no stress urinary incontinence) were included in the data analysis from an observational, case-controlled study. The Vaginal Tactile Imager (VTI) was used with an analytical software package to automatically calculate 52 biomechanical parameters for 8 VTI test procedures (probe insertion, elevation, rotation, Val-salva maneuver, voluntary muscle contractions in 2 planes, relaxation, and reflex contraction). The ranges, mean values, and standard deviations for all 52 VTI parameters were established. 12 VTI parameters were identified as statistically sen-sitive (p < 0.05; t-test) to the subject age; 9 parameters were identified as statistically sensitive (p < 0.05; t-test) to the subject parity; no sensitivity was found to subject weight. Among the 12 parameters sensitive to women's age, 6 parameters show changes (decrease) in tissue elasticity and 6 parameters show weakness in pelvic muscle functions with age. Among the 9 parameters sensitive to parity, 5 parameters show changes (decrease) in tissue elasticity and 4 parameters show weakness in pelvic muscle functions after giving birth. The biomechanical mapping of the female pelvic floor with the VTI provides a unique set of parameters characterizing pelvic changes with age and parity. These objectively measurable biomechanical transformations of pelvic tissues, support structures, and functions may be used in future research and practical applications.

Optical palpation for the visualization of tumor in human breast tissue

Accurate and effective removal of tumor in one operation is an important goal of breast-conserving surgery. However, it is not always achieved. Surgeons often utilize manual palpation to assess the surgical margin and/or the breast cavity. Manual palpation, however, is subjective and has relatively low resolution. Here, we investigate a tactile imaging technique, optical palpation, for the visualization of tumor. Optical palpation generates maps of the stress at the surface of tissue under static preload compression. Stress is evaluated by measuring the deformation of a contacting thin compliant layer with known mechanical properties using optical coherence tomography. In this study, optical palpation is performed on 34 freshly excised human breast specimens. Wide field-of-view (up to ~46 × 46 mm) stress images, optical palpograms, are presented from four representative specimens, demonstrating the capability of optical palpation to visualize tumor. Median stress reported for adipose tissue, 4 kPa, and benign dense tissue, 8 kPa, is significantly lower than for invasive tumor, 60 kPa. In addition, we demonstrate that optical palpation provides contrast consistent with a related optical technique, quantitative micro-elastography. This study demonstrates that optical palpation holds promise for visualization of tumor in breast-conserving surgery.

Biomechanical Mapping of the Female Pelvic Floor: Uterine Prolapse Versus Normal Conditions

INTRODUCTION

Quantitative biomechanical characterization of pelvic supportive structures and functions in vivo is thought to provide insight into the pathophysiology of pelvic organ prolapse (POP). Vaginal tactile imaging is an innovative approach to the biomechanical mapping of the female pelvic floor to quantify tissue elasticity, pelvic support, and pelvic muscle functions. The Vaginal Tactile Imager (VTI) records high definition pressure patterns through the vaginal walls under an applied tissue deformation and during pelvic floor muscle contractions.

OBJECTIVE

The objective of this study is to explore an extended set of 52 biomechanical parameters of the female pelvis for the differentiation and characterization of uterine prolapse relative to normal pelvic floor conditions.

METHODS

Sixty subjects were included in the data analysis from observational and case-controlled studies. Out of these 60, forty-two subjects had normal pelvic floor conditions and 18 subjects had uterine prolapse (no anterior, no posterior prolapse). The VTI, model 2S, was used with an analytical software package to automatically calculate 52 biomechanical parameters for 8 VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in 2 planes, relaxation, and reflex contraction).

RESULTS

The ranges, mean values, and standard deviations for all 52 VTI parameters were established. Twenty-two of 52 parameters were identified as statistically sensitive (p < 0.05; t-test) to the development of uterine prolapse. Among these 21 parameters, 6 parameters show changes (decrease) in tissue elasticity, 5 parameters show deteriorations in pelvic support, and 10 parameters show weakness in muscle functions for uterine prolapsed versus normal conditions.

CONCLUSION

The biomechanical mapping of the female pelvic floor with the VTI provides a unique set of parameters characterizing uterine prolapse versus normal conditions. These objectively measurable biomechanical transformations of pelvic tissues, support structures, and functions under the prolapse conditions may be useful in future research and practical applications.

Biomechanical Mapping of the Female Pelvic Floor: Prolapse versus Normal Conditions

Background:

Quantitative biomechanical characterization of pelvic supportive structures and functions in vivo is thought to provide insight into pathophysiology of pelvic organ prolapse (POP). An innovative approach—vaginal tactile imaging—allows biomechanical mapping of the female pelvic floor to quantify tissue elasticity, pelvic support, and pelvic muscle functions. The Vaginal Tactile Imager (VTI) records high definition pressure patterns from vaginal walls under an applied tissue deformation and during pelvic floor muscle contractions.

Objective:

To explore an extended set of 52 biomechanical parameters for differentiation and characterization of POP relative to normal pelvic floor conditions.

Methods:

96 subjects with normal and POP conditions were included in the data analysis from multi-site observational, case-controlled studies; 42 subjects had normal pelvic floor conditions and 54 subjects had POP. The VTI, model 2S, was used with an analytical software package to calculate automatically 52 biomechanical parameters for 8 VTI test procedures (probe insertion, elevation, rotation, Valsalva maneuver, voluntary muscle contractions in 2 planes, relaxation, and reflex contraction). The groups were equalized for subject age and parity.

Results:

The ranges, mean values, and standard deviations for all 52 VTI parameters were established. 33 of 52 parameters were identified as statistically sensitive (p < 0.05; t-test) to the POP development. Among these 33 parameters, 11 parameters show changes (decrease) in tissue elasticity, 8 parameters show deteriorations in pelvic support and 14 parameters show weakness in muscle functions for POP versus normal conditions.

Conclusions:

The biomechanical mapping of the female pelvic floor with the VTI provides a unique set of parameters characterizing POP versus normal conditions. These objectively measurable biomechanical transformations of pelvic tissues, support structures, and functions under POP may be used in future research and practical applications.

Quantitative Assessment and Interpretation of Vaginal Conditions

Introduction

Few means exist to provide quantitative and reproducible assessment of vaginal conditions from biomechanical and functional standpoints.

Aim

To develop a new approach for quantitative biomechanical characterization of the vagina.

Methods

Vaginal tactile imaging (VTI) allows biomechanical assessment of soft tissue and function along the entire length of the anterior, posterior, and lateral vaginal walls. This can be done at rest, with applied vaginal deformation, and with pelvic muscle contraction.

Results

Data were analyzed for 42 subjects with normal pelvic floor support from an observational case-controlled clinical study. The average age was 52 years (range = 26–90 years). We introduced 8 VTI parameters to characterize vaginal conditions: (i) maximum resistance force to insertion (newtons), (ii) insertion work (millijoules), (iii) maximum stress-to-strain ratio (elasticity; kilopascals per millimeter), (iv) maximum pressure at rest (kilopascals), (v) anterior-posterior force at rest (newtons), (vi) left-right force at rest (newtons), (vii) maximum pressure at muscle contraction (kilopascals), and (viii) muscle contraction force (newtons). We observed low to moderate correlation of these parameters with subject age and no correlation with subject weight. 6 of 8 parameters demonstrated a P value less than .05 for 2 subject subsamples divided by age (≤52 vs >52 years), which means 6 VTI parameters change with age.

Conclusions

VTI allows biomechanical and functional characterization of the vaginal conditions that can be used for (i) understanding “normal” vaginal conditions, (ii) quantification of the deviation from normality, (iii) personalized treatment (radiofrequency, laser, or plastic surgery), and (iv) assessment of the applied treatment outcome.

Egorov V, Murphy M, Lucente V, et al. Quantitative Assessment and Interpretation of Vaginal Conditions. Sex Med 2018;6:39–48.

Measuring tissue displacement of the anterior vaginal wall using the novel aspiration technique in vivo

Little is known about the mechanical properties of pelvic floor structures and their role in the course and treatment of pelvic organ prolapse (POP). We hypothesize that in vivo mechanical properties of the vaginal wall are related to the appearance of POP and pre-and post-operative states. We used a suction device for intravaginal application, the aspiration device, to evaluate two in vivo mechanical parameters of the anterior vaginal wall, the load dependent tissue displacement and the initial displacement, by image analysis in pre- and post-menopausal women with (POP) and without (control) cystocele (POP: pre-menopausal: N = 6, post-menopausal: N = 19, control: pre-menopausal: N = 17, post-menopausal: N = 6). Mechanical parameters in women with and without cystocele and pre- and post-operative parameters were compared. Statistically significant differences were observed between the two mechanical parameters in pre- and post-operative states (P = 0.04, P = 0.03), but not between the parameters for women with and without cystocele (P = 0.92, P = 0.75). The mechanical behavior of pelvic floor structures is influenced by factors such as POP, age or estrogenization that are apparent at different length scales, which cannot be separated by the aspiration based biomechanical measurements. When comparing pre- and post-operative states of the same patient, a firmer tissue response was observed after intervention.

Biomechanical paradigm and interpretation of female pelvic floor conditions before a treatment

BACKGROUND

Further progress in restoring a woman's health may be possible if a patient with a damaged pelvic floor could undergo medical imaging and biomechanical diagnostic tests. The results of such tests could contribute to the analysis of multiple treatment options and suggest the optimal one for that patient.

AIM

To develop a new approach for the biomechanical characterization of vaginal conditions, muscles, and connective tissues in the female pelvic floor.

METHODS

Vaginal tactile imaging (VTI) allows biomechanical assessment of the soft tissue along the entire length of the anterior, posterior, and lateral vaginal walls at rest, with manually applied deflection pressures and with muscle contraction, muscle relaxation, and Valsalva maneuver. VTI allows a large body of measurements to evaluate individual variations in tissue elasticity, support defects, as well as pelvic muscle function. Presuming that 1) the female pelvic floor organs are suspended by ligaments against which muscles contract to open or close the outlets and 2) damaged ligaments weaken the support and may reduce the force of muscle contraction, we made an attempt to characterize multiple pelvic floor structures from VTI data.

RESULTS

All of the 138 women enrolled in the study were successfully examined with the VTI. The study subjects have had normal pelvic support or pelvic organ prolapse (stages I-IV). The average age of this group of subjects was 60±15 years. We transposed a set of 31 VTI parameters into a quantitative characterization of pelvic muscles and ligamentous structures. Interpretation of the acquired VTI data for normal pelvic floor support and prolapse conditions is proposed based on biomechanical assessment of the functional anatomy.

CONCLUSION

Vaginal tactile imaging allows biomechanical characterization of female pelvic floor structures and tissues in vivo, which may help to optimize treatment of the diseased conditions such as prolapse, incontinence, atrophy, and some forms of pelvic pain.

Real-time measurement of the vaginal pressure profile using an optical-fiber-based instrumented speculum

Pelvic organ prolapse (POP) occurs when changes to the pelvic organ support structures cause descent or herniation of the pelvic organs into the vagina. Clinical evaluation of POP is a series of manual measurements known as the pelvic organ prolapse quantification (POP-Q) score. However, it fails to identify the mechanism causing POP and relies on the skills of the practitioner. We report on a modified vaginal speculum incorporating a double-helix fiber-Bragg grating structure for distributed pressure measurements along the length of the vagina and include preliminary data in an ovine model of prolapse. Vaginal pressure profiles were recorded at 10 Hz as the speculum was dilated incrementally up to 20 mm. At 10-mm dilation, nulliparous sheep showed higher mean pressures ( 102 ± 46 ?? mmHg ) than parous sheep ( 39 ± 23 ?? mmHg ) ( P = 0.02 ), attributable largely to the proximal (cervical) end of the vagina. In addition to overall pressure variations, we observed a difference in the distribution of pressure that related to POP-Q measurements adapted for the ovine anatomy, showing increased tissue laxity in the upper anterior vagina for parous ewes. We demonstrate the utility of the fiber-optic instrumented speculum for rapid distributed measurement of vaginal support.

Instrumental tactile diagnostics in robot-assisted surgery

BACKGROUND

Robotic surgery has gained wide acceptance due to minimizing trauma in patients. However, the lack of tactile feedback is an essential limiting factor for the further expansion. In robotic surgery, feedback related to touch is currently kinesthetic, and it is mainly aimed at the minimization of force applied to tissues and organs. Design and implementation of diagnostic tactile feedback is still an open problem. We hypothesized that a sufficient tactile feedback in robot-assisted surgery can be provided by utilization of Medical Tactile Endosurgical Complex (MTEC), which is a novel specialized tool that is already commercially available in the Russian Federation. MTEC allows registration of tactile images by a mechanoreceptor, real-time visualization of these images, and reproduction of images via a tactile display.

MATERIALS AND METHODS

Nine elective surgeries were performed with da Vinci™ robotic system. An assistant performed tactile examination through an additional port under the guidance of a surgeon during revision of tissues. The operating surgeon sensed registered tactile data using a tactile display, and the assistant inspected the visualization of tactile data. First, surgeries where lesion boundaries were visually detectable were performed. The goal was to promote cooperation between the surgeon and the assistant and to train them in perception of the tactile feedback. Then, instrumental tactile diagnostics was utilized in case of visually undetectable boundaries.

RESULTS

In robot-assisted surgeries where lesion boundaries were not visually detectable, instrumental tactile diagnostics performed using MTEC provided valid identification and localization of lesions. The results of instrumental tactile diagnostics were concordant with the results of intraoperative ultrasound examination. However, in certain cases, for example, thoracoscopy, ultrasound examination is inapplicable, while MTEC-based tactile diagnostics can be efficiently utilized.

CONCLUSION

The study proved that MTEC can be efficiently used in robot-assisted surgery allowing correct localization of visually undetectable lesions and visually undetectable boundaries of pathological changes of tissues.

Tactile Imaging Markers to Characterize Female Pelvic Floor Conditions

The Vaginal Tactile Imager (VTI) records pressure patterns from vaginal walls under an applied tissue deformation and during pelvic floor muscle contractions. The objective of this study is to validate tactile imaging and muscle contraction parameters (markers) sensitive to the female pelvic floor conditions. Twenty-two women with normal and prolapse conditions were examined by a vaginal tactile imaging probe. We identified 9 parameters which were sensitive to prolapse conditions (p < 0.05 for one-way ANOVA and/or p < 0.05 for t-test with correlation factor r from -0.73 to -0.56). The list of parameters includes pressure, pressure gradient and dynamic pressure response during muscle contraction at identified locations. These parameters may be used for biomechanical characterization of female pelvic floor conditions to support an effective management of pelvic floor prolapse.

Characterizing female pelvic floor conditions by tactile imaging

Introduction and hypothesis

Tactile imaging (TI) is the high-definition pressure mapping technology which allows recording pressure patterns from vaginal walls under applied load and during pelvic floor muscle contraction. The objective of this study was to identify new tactile imaging and muscle contraction markers to characterize female pelvic floor conditions.

Methods

The study subjects included 22 women with normal and prolapse conditions. They were examined by a new vaginal tactile imaging probe that images the entire vagina, the pelvic floor support structures, and pelvic floor muscle contractions.

Results

We identified 11 parameters as potential markers to characterize the female pelvic floor conditions. These parameters correlate with prolapse conditions, patient age, and parity.

Conclusions

Our findings suggest that the tactile imaging markers such as pressure, pressure gradient, and dynamic pressure response during muscle contraction may be used for further quantitative characterization of female pelvic floor conditions.

Electronic supplementary material

The online version of this article (doi:10.1007/s00192-014-2549-9) contains supplementary material, which is available to authorized users. This video is also available to watch on http://videos.springer.com/. Please search for the video by the article title.

Biomechanical properties and associated collagen composition in vaginal tissue of women with pelvic organ prolapse

PURPOSE

The pelvic tissue of women with pelvic organ prolapse is stiffer than that of controls but there are scant data on the collagen composition that corresponds to these mechanical properties. We evaluated human vaginal wall stiffness using the novel scanning haptic microscope and correlated these measurements to collagen expression in women with and without pelvic organ prolapse. In this simultaneous biomechanical and biochemical assessment we evaluated the usefulness of this measurement technology for pelvic floor disorder research and confirmed an association between mechanical properties and composition.

MATERIALS AND METHODS

The elastic constant (a measure of stiffness) of vaginal wall tissue was measured with the scanning haptic microscope. Protein expression of collagen types I and III of the same tissues were determined by Western blot. The Student t test was used for comparisons between groups.

RESULTS

The anterior and posterior vaginal walls of premenopausal and postmenopausal women with pelvic organ prolapse were significantly stiffer than those of controls (p <0.05). Collagen III protein expression in the anterior vaginal wall in the control group was higher than in menopausal women. Collagen I expression was not significantly different between controls and cases.

CONCLUSIONS

The scanning haptic microscope produced reliable mechanical measurements in small tissue samples without tissue destruction. Vaginal wall tissues are stiffer in women with pelvic organ prolapse than in controls. This vaginal wall stiffness was associated with lower protein expression of collagen III in the vaginal wall compared to that in asymptomatic controls.

Quantifying vaginal tissue elasticity under normal and prolapse conditions by tactile imaging

INTRODUCTION AND HYPOTHESIS

Vaginal tactile imaging (VTI) is based on principles similar to those of manual palpation. The objective of this study is to assess the clinical suitability of new approach for imaging and tissue elasticity quantification under normal and prolapse conditions.

METHODS

The study subjects included 31 women with normal and prolapse conditions. The tissue elasticity (Young's modulus) was calculated from spatial gradients in the resulting 3-D tactile images.

RESULTS

Average values for tissue elasticity for the anterior and posterior compartments for normal conditions were 7.4 ± 4.3 kPa and 6.2 ± 3.1 kPa respectively. For Stage III prolapse the average values for tissue elasticity for anterior and posterior compartments were 1.8 ± 0.7 kPa and 1.8 ± 0.5 kPa respectively.

CONCLUSIONS

VTI may serve as a means for 3-D imaging of the vagina and a quantitative assessment of vaginal tissue elasticity, providing important information for furthering our understanding of pelvic organ prolapse and surgical treatment.