MRI visible Fe3O4 polypropylene mesh: 3D reconstruction of spatial relation to bony pelvis and neurovascular structures

Abstract

Introduction and hypothesis To demonstrate mesh magnetic resonance (MR) visibility in living women, the feasibility of reconstructing the full mesh course in 3D and document its spatial relationship to pelvic anatomical structures. Methods This is a proof of concept study of three patients from a prospective multi-center trial evaluating women with anterior vaginal mesh repair using a MR-visible Fe3O4-polypropylene implant for pelvic floor reconstruction. High resolution sagittal T2-weighted sequences, transverse T1-weighted (T1w) FLASH 2D and transverse T1w FLASH 3D sequences were performed to evaluate Fe3O4-polypropylene mesh MR-visibility and overall postsurgical pelvic anatomy three months after reconstructive surgery. Full mesh course as well as important pelvic structures were reconstructed using the 3D Slicer® software program based on T1 and T2 MR-images. Results Three women with POP-Q grade III cystoceles were successfully treated with a partially absorbable MR-visible anterior vaginal mesh with 6 fixation arms showing no recurrent cystocele in the 3 months follow-up examination. The course of mesh in the pelvis was visible on MR-images in all three women. The mesh body and arms could be reconstructed allowing visualization of the full course of the mesh in relationship to important pelvic structures such as the obturator or pudendal vessel-nerve bundles in 3D. Conclusions The use of MR-visible Fe3O4-polypropylene meshes in combination with post-surgical 3D reconstruction of the mesh and adjacent structures is feasible suggesting it might be a useful tool to more precisely evaluate mesh complications and might be a valuable interactive feedback tool for surgeons and mesh design engineers.

3D reconstruction of MR‐visible Fe3O4‐mesh implants: Pelvic mesh measurement techniques and preliminary findings

“…These two meshes only differ in size and shape (eg, 103 mm vertical mesh length and diamond‐shaped body of the Seratom E PA vs 90 mm vertical mesh length and rectangular‐shaped body in the Seratom P PA; Supplemental Figure S1). Both meshes have six arms and MR‐visible Fe 3 O 4 threads integrated into the weave, alternating with absorbable fibers expected to be absorbed approximately 120 days postsurgically . Mesh implantations were performed according to the manufactuerer's recommendations by expert surgeons (>1000 anterior vaginal meshes implanted).…”

“…All MRIs were acquired in supine position using a 1.5 Tesla scanner (Siemens Symphony, Siemens Medical Solutions, Erlangen, Germany) . High‐resolution T2‐weighted (T2w) turbo spin echo sequence on axial, coronal, and sagittal planes were acquired according to the body axis to visualize the pelvic anatomy (TR 3460‐4219 ms, TE 77‐88 ms, matrix 512*282, slice thickness 5‐6 mm), whereas T1‐weighted (T1w) FLASH 2D (TR 128‐132 ms, TE 4.7 ms, matrix 256*154, slice thickness 6 mm), and FLASH 3D sequences (TR 15 ms, TE 6 ms, matrix 512*384, slice thickness 1 mm) were performed to visualize the implanted meshes . This study focused on the analysis of the 3‐month and 1‐year postoperative MRIs.…”

“…We used bony landmark‐based method to align all MRIs instead of automatic rigid/deformable registration methods to limit the influence of soft tissue variation of the pelvic organs, such as abdominal wall motion, movement of intestines, variation of bladder filling, and intestine contents variation. In 3D Slicer®, we first manually identify the bony landmarks including the most inferior part of the pubic symphysis, ischial spines, and the sacrococcygeal junction on all MRI sequences . Then a semi‐automatic landmark‐based rigid registration method in 3D Slicer® was used to align all MRI sequences at both the 3‐month and 2‐year postoperative exams in the same 3D space with standardized bony pelvis orientation .…”

“…Ultrasound as a standard imaging tool in urogynecology has demonstrated its ability to visualize the mesh material and describe its relation to adjacent pelvic organs . However, it is limited when attempting to visualize mesh deep in the body, including the anchoring points and their relationship to neurovascular structures . The pudendal and obturator neurovascular bundles, for example, are at risk of being injured intraoperatively due to their proximity to the recommended mesh arm anchoring points …”

“…Newly developed magnetic resonance (MR)‐visible Fe3O4‐polypropylene partially absorbable meshes in combination with pelvic MR‐imaging (MRI) allow visual observation of the full mesh course through the female pelvis, yet objective measurement schemes are scarce . In this study, we aim to develop measurement techniques to (i) quantify the dimensions of the implanted mesh to evaluate changes in size compared to its pre‐implant dimension (“shrinkage”); (ii) measure the distance from implanted mesh to important pelvic structures and compare them with mesh implantation recommendations; and (iii) correlate the measurement information with patients’ clinical results.…”