transvaginal-mesh-insertion-in-the-ovine-model

Transvaginal Mesh Insertion in the Ovine Model

This protocol describes mesh insertion into the rectovaginal septum in sheep using a single vaginal incision technique, with and without the trocar-guided ...

Clinical Specialties Research Groups, Faculty of Medicine, KU Leuven

Convection-enhanced delivery (CED) is a promising technique to deliver large molecular weight drugs to the human brain for treatment of Parkinson's, Alzheimer's, or brain tumors. Researchers have used agarose gels to study mechanisms of agent transport in soft tissues like brain due to its similar mechanical and transport properties. However, inexpensive quantitative techniques to precisely measure achieved agent distribution in agarose gel phantoms during CED are missing. Such precise measurements of concentration distribution are needed to optimize drug delivery. An optical experimental method to accurately quantify agent concentration in agarose is presented. A novel geometry correction algorithm is used to determine real concentrations from observable light intensities captured by a digital camera. We demonstrate the technique in dye infusion experiments that provide cylindrical and spherical distributions when infusing with porous membrane and conventional single-port catheters, respectively. This optical method incorporates important parameters, such as optimum camera exposure, captured camera intensity calibration, and use of collimated light source for maximum precision. We compare experimental results with numerical solutions to the convection diffusion equation. The solutions of convection-diffusion equations in the cylindrical and spherical domains were found to match the experimental data obtained by geometry correction algorithm.

Methods for determining agent concentration profiles in agarose gel during convection-enhanced delivery.

Our aim was to analyze the apparent contraction of meshes in vivo after abdominal wall reconstruction and evaluate histological and biomechanical properties after explantation.

Mesh contraction: in vivo documentation of changes in apparent surface area utilizing meshes visible on magnetic resonance imaging in the rabbit abdominal wall model.

Our primary objective was to develop relevant algorithms for quantification of mesh position and 3D shape in magnetic resonance (MR) images.

Three-dimensional analysis of implanted magnetic-resonance-visible meshes.

Immediate post-operative structural changes in implanted synthetic meshes are believed to contribute to graft related complications. Our aim was to observe in vivo dimensional changes at the pore level.

Immediate postoperative changes in synthetic meshes - In vivo measurements.

Fetal skull molding is important for the adaptation of the head to the birth canal during vaginal delivery. Importantly, the fetal head must rotate around the maternal symphysis pubis. The goals of this analysis were to observe a human birth in real-time using an open magnetic resonance imaging (MRI) scanner and describe the fetal head configuration during expulsion.

Evaluating fetal head dimension changes during labor using open magnetic resonance imaging.

Pelvic organ prolapse affects half of vaginally parous women. Several animal models are used to study its pathophysiology and treatment. Sheep are interesting because they develop spontaneously prolapse with similar risk factors as women and can be used for vaginal surgery. This study describes ovine pelvis anatomy and compares it to women's pelvis to provide anatomical tools for translational researchers.

Comparative Anatomy of the Ovine and Female Pelvis.

With advancing population age, pelvic-floor dysfunction (PFD) will affect an increasing number of women. Many of these women wish to maintain active lifestyles, indicating an urgent need for effective strategies to treat or, preferably, prevent the occurrence of PFD. Childbirth and pregnancy have both long been recognized as crucial contributing factors in the pathophysiology of PFD. Vaginal delivery of a child is a serious traumatic event, causing anatomical and functional changes in the pelvic floor. Similar changes to those experienced during childbirth can be found in symptomatic women, often many years after delivery. Thus, women with such PFD symptoms might have incompletely recovered from the trauma caused by vaginal delivery. This hypothesis creates the possibility that preventive measures can be initiated around the time of delivery. Secondary prevention has been shown to be beneficial in patients with many other chronic conditions. The current general consensus is that clinicians should aim to minimize the extent of damage during delivery, and aim to optimize healing processes after delivery, therefore preventing later dysfunction. A substantial amount of research investigating the potential of stem-cell injections as a therapeutic strategy for achieving this purpose is currently ongoing. Data from small animal models have demonstrated positive effects of mesenchymal stem-cell injections on the healing process following simulated vaginal birth injury.

Cell-based secondary prevention of childbirth-induced pelvic floor trauma.

Vaginal childbirth is believed to be a significant risk factor for the development of pelvic floor dysfunction later in life. Previous studies have explored the use of medical imaging and simulations of childbirth to determine the stretch in the levator ani muscle. A report in 2012 has recorded magnetic resonance images of a live childbirth of a 24 year old woman giving birth vaginally for the second time, using a 1.0 Tesla open, high-field scanner. Our objective was to determine the stretch ratios in the levator muscle using these magnetic resonance images of live childbirth.

Article	Year
Methods for determining agent concentration profiles in agarose gel during convection-enhanced delivery. IEEE transactions on bio-medical engineering\| PubMed ID: 21342811	2011
Mesh contraction: in vivo documentation of changes in apparent surface area utilizing meshes visible on magnetic resonance imaging in the rabbit abdominal wall model. International urogynecology journal\| PubMed ID: 24448724	2014
Three-dimensional analysis of implanted magnetic-resonance-visible meshes. International urogynecology journal\| PubMed ID: 25800904	2015
Immediate postoperative changes in synthetic meshes - In vivo measurements. Journal of the mechanical behavior of biomedical materials\| PubMed ID: 26594782	2015
Evaluating fetal head dimension changes during labor using open magnetic resonance imaging. Journal of perinatal medicine\| PubMed ID: 27219097	2016
Comparative Anatomy of the Ovine and Female Pelvis. Gynecologic and obstetric investigation\| PubMed ID: 28125816	2017
Cell-based secondary prevention of childbirth-induced pelvic floor trauma. Nature reviews. Urology\| PubMed ID: 28374792	2017
In vivo evidence of significant levator ani muscle stretch on MR images of a live childbirth. American journal of obstetrics and gynecology\| PubMed ID: 28412085	2017

Nikhil Sindhwani

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