[Show abstract][Hide abstract] ABSTRACT: Reinforcement of tissues by use of textiles is encouraged by the reduced rate of recurrent tissue dehiscence but for the price of an inflammatory and fibrotic tissue reaction to the implant. The latter mainly is affected by the size of the pores, whereas only sufficiently large pores are effective in preventing a complete scar entrapment. Comparing two different sling implants (TVT and SIS), which are used for the treatment of urinary incontinence, we can demonstrate that the measurement of the effective porosity reveals considerable differences in the textile construction. Furthermore the changes of porosity after application of a tensile load can indicate a structural instability, favouring pore collapse at stress and questioning the use for purposes that are not “tension-free.”
[Show abstract][Hide abstract] ABSTRACT: From a surgeon's point of view, meshes implanted for inguinal hernia repair should overlap the defect by 3 cm or more during implantation to avoid hernia recurrence secondary to mesh shrinkage. The use of magnetic resonance imaging (MRI)-visible meshes now offers the opportunity to noninvasively monitor whether a hernia is still covered sufficiently in the living patient. The purpose of this study was therefore to evaluate the efficacy of hernia repair after mesh implantation based on MRI findings (mesh coverage, visibility of hernia structures) and based on the patient's postoperative symptoms.
In this prospective study approved by the ethics committee, 13 MRI-visible meshes were implanted in 10 patients (3 bilaterally) for inguinal hernia repair between March 2012 and January 2013. Senior visceral surgeons (>7 years of experience) implanted the meshes via laparoscopic transabdominal preperitoneal procedure. Magnetic resonance imaging was performed within 1 week and at 3 months after surgery at a 1.5-T system. Mesh position, deformation, and coverage of the hernia were visually assessed in consensus and rated on a 4-point semiquantitative scoring system. Distances of hernia center point to the mesh borders (overlap) were measured. Mesh position and hernia coverage postoperatively and at 3 months after implantation were correlated with the respective patients' clinical symptoms. Statistical analysis was performed using the Wilcoxon signed rank test.
Two of the 13 meshes presented with an atypical mesh configuration along the course of psoas muscle with a short medial overlap of less than 2 cm. Eleven of the 13 meshes exhibited a typical mesh configuration with lateral folding and initial overlap of more than 2 cm. Between baseline and 3 months' follow-up, average overlap decreased in the medial direction by -10% (3.75 cm vs 3.36 cm, P = 0.22), in the lateral direction by -20% (3.55 cm vs 2.82 cm, P = 0.01), in the superior direction by -2% (5.82 cm vs 5.72 cm, P = 0.55), and in the posterior direction by -19% (4.11 cm vs 3.34 cm, P = 0.01). Between baseline and 3 months' follow-up, mesh folding increased mildly in the medial direction, whereas no change was found in the other directions. Individual folds of the mesh were flexible over time, whereas the gross visual configuration and location of meshes did not change. Four of the 13 former hernia sites were mildly painful at follow-up, whereas 9 of the 13 were completely asymptomatic. No correlation between clinical symptoms and mesh position or hernia coverage was found.
Our results suggest that the actual postoperative mesh position after release of laparoscopic pneumoperitoneum may deviate from its position during surgery. Gross mesh position and configuration differed between patients but did not change within a given patient over the observation period of 3 months after surgery. We did not find a correlation between clinical symptoms and mesh configuration or position. Shrinkage of meshes does occur, yet not as concentric process, but regionally variable, leading to a reduced hernia coverage of up to -20% in the lateral and posterior directions.
[Show abstract][Hide abstract] ABSTRACT: Background Trauma, vascular lesions or peritonitis can cause an increase of the intra-abdominal pressure (IAP) or an abdominal compartment syndrome (ACS). Maintaining the cardiac output (CO) cannot prevent impairment of organ function. However, it is unknown, whether an IAP of 30 mmHg can lead to oragn damage within 6 an 12 h despite unchanged CO.
Methods We examined 16 male pigs (50 kg, SD 1,8). Animals were ventilated volume controlled and analogue-sedated using ketamine and pentobarbital. Via CO2-pneumoperitoneum, IAD was increased to 30 mmHg for 6 and 12 h (each n = 6). In the control (n = 4) the IAP remained unchanged. Heartrate (HR), mean arterial pressure (MAP), central venous pressure (CVP), CO and peak inspiratory pressure (PIP) were continuously recorded. Additional to basic fluid replacement (2 ml/kg/h) crystalloid volume was given whenever continuously monitored CO was below control values. In the end, animals were given an overdose of pentobarbital and specimen were taken from lung, heart, kidney, liver stomach as well as small and large bowel. Damage of bowel specimen was classified according to Park whereas damage to other organs was classified as none, low, intermediate and high. Statistic analysis was performed using ANOVA and post-hoc analysis together with paired tests. A p < 0,05 was considered significant and was adjusted (Bonferroni) when multiple paired testing was performed.
Results A significant increase of CVP and PIP was found whereas the other haemodynamic data was not changed. Compared to control, an increased morphologic damage was found in lung, stomach (12 h), liver, bowel and kidney. The myocardium was statistically unchanged.
Conclusion Even a short-termed increase of the IAP for 6 h results in morphologic organ impairment despite an unchanged CO. In the clinical regard, these results imply an immediate decompression in the presence of a critically increased IAP.
Archives of Disease in Childhood 10/2014; 99(Suppl 2):A359-A360. DOI:10.1136/archdischild-2014-307384.997 · 2.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Background:
Application of a mesh in presence of pneumoperitoneum may cause deformation or wave formation when gas is released. Moreover, mesh shrinkage during subsequent wound healing cannot be detected in vivo without invasive diagnostics. Using MRI-visible polyvinylidene fluoride (PVDF) mesh, the extend of mesh deformation and shrinkage could be objectified by MRI for the first time.
Materials and methods:
Laparoscopic intraperitoneal onlay mesh (IPOM) implantation was performed in 10 female rabbits using ferro-oxide loaded PVDF meshes. MRI measurements were performed postoperatively at days 1 and 90. After three-dimensional reconstruction of all MRI images the total surface and the effective surface of the implanted mesh were explored and calculated computer-assisted.
In all cases, the mesh could be identified in MRI. The subsequent three-dimensional reconstruction always allowed a calculation of the mesh area. In relation to the original size of the used textile implant, we found neither a significant reduction of the effective mesh surface after release of the pneumoperitoneum at day 1 after laparoscopic surgery nor a significant change of the total surface of this large pore mesh by the end of the observation period.
In vivo investigation of mesh surface via MRI could exclude a significant initial reduction of the effective mesh surface after release of pneumoperitoneum, in this IPOM rabbit model. A further subsequent shrinkage of these large pore PVDF meshes could be excluded, as well. Imaging of MRI-visible IPOM mesh turned out to be a sufficient tool to objectify mesh configuration and position in vivo.
Journal of Biomedical Materials Research Part B Applied Biomaterials 08/2014; 102(6). DOI:10.1002/jbm.b.33098 · 2.76 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Introduction:
After two-dimensional plane MRI-visible mesh implants could be successfully visualized in phantom and small animal model, the aim of the underlying study was to explore the feasibility of an MRI visualization of complex three-dimensional mesh geometry in close contact to the intestine. We therefore used a MR-visible three-dimensional intra-peritoneal stoma (IPST) mesh in a porcine model.
Materials and methods:
Laparoscopic terminal sigmoid colostomy has been done with implantation of a prophylactic MRI-visible IPST mesh in two animals. MRI investigations were done after 1 week, 6 months and in case of clinical impairment. These findings were compared to endoscopy and makroscopical and histological investigation of the preparation.
The first animal has to be killed because of an ileus 4 weeks after operation. The second animal has to be killed after 7 weeks because of recurrent obstipation. In all cases MRI investigation could identify the IPST mesh and could clearly separate between mesh and intestine. MRI revealed a big bowl ileus due to a funnel dislocation in the first animal. In the second animal, MR diagnostic explored a functional stenosis because of a too small diameter of the central funnel in combination with sticky feces and distension of the terminal sigmoid before discharging into the funnel. Endoscopy, makroscopical and histological investigation of the preparation supported MRI findings.
Although complicate clinical course was a diagnostic challenge exploring 3D implants such as IPST, visualization of this new MRI-visible IPST mesh could be proved and turned out as an effective diagnostic possibility. Further studies are necessary to analyze long-time effects such as shrinkage, mesh migration and tissue integration using MRI scanning.
[Show abstract][Hide abstract] ABSTRACT: Purpose: Use of textile structures for reinforcement of pelvic floor structures has to consider mechanical forces to the implant, which are quite different to the tension free conditions of the abdominal wall. Thus, biomechanical analysis of textile devices, have to include the impact of strain on stretchability and effective porosity. Material and methods: Prolift® and Prolift + M®, developed for tension free conditions, were tested by measuring stretchability and effective porosity applying mechanical strain. For comparison we used Dynamesh - PR4®, which was designed for pelvic floor repair to withstand mechanical strain. Results: Prolift® at rest showed moderate porosity with little stretchability but complete loss of effective porosity at strain of 4.9 N/cm. Prolift + M® revealed an increased porosity at rest, but at strain showed high stretchability, with subsequent loss of effective porosity at strain of 2.5 N/cm. Dynamesh PR4® preserved its high porosity even under strain, but as consequence of limited stretchability. Conclusions: Though in tension free conditions Prolift® and Prolift + M® can be considered as large pore class I meshes, application of mechanical strain rapidly lead to collapse of pores. The loss of porosity at mechanical stress can be prevented by constructions with high structural stability. Assessment of porosity under strain was found helpful to define requirements for pelvic floor devices. Clinical studies have to prove whether devices with high porosity as well as high structural stability can improve the patients' outcome.
Journal of Biomedical Materials Research Part A 04/2014; 102(4). DOI:10.1002/jbm.a.34767 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Shrinkage and deformation of mesh implants used for hernia treatment can be the cause of long-term complications. The purpose of this study was to quantify noninvasively time-dependent mesh shrinkage, migration, and configuration changes in patients who were surgically treated for inguinal hernia using magnetic resonance imaging (MRI)-visible mesh implants.
In an agarose phantom, meshes in different shrinkage and folding conditions were used to validate the quantification process. Seven patients who were surgically (3 bilaterally) treated for inguinal hernia using iron-loaded mesh implants were prospectively examined using MRI. Gradient echo sequences in sagittal and transverse orientations were performed on day 1 after surgery and at day 90. The mesh-induced signal voids were semiautomatically segmented and a polygonal surface model was generated. A comparison of area and centroid position was performed between the 2 calculated surfaces (day 1 vs day 90).
The phantom study revealed a maximum deviation of 3.6% between the MRI-based quantification and the actual mesh size. All 10 implants were successfully reconstructed. The mean (SD) observed mesh shrinkage 90 days after surgery was 20.9% (7.1%). The mean (SD) centroid movement was 1.17 (0.47) cm. Topographic analysis revealed mean (SD) local configuration changes of 0.23 (0.03) cm.
In this study, significant mesh shrinkage (20.9%) but marginal changes in local mesh configuration occurred within 90 days after mesh implantation. Centroid shift of the mesh implant can be traced back to different patient positioning and abdominal distension. The developed algorithm facilitates noninvasive assessment of key figures regarding MRI-visible meshes. Consequently, it might help to improve mesh technology as well as surgical skills.
[Show abstract][Hide abstract] ABSTRACT: PURPOSE
Surgical hernia treatments using polymer based mesh implants are one of the most frequent operations worldwide. As the implants are invisible using conventional imaging methods, iron-oxides were integrated into the mesh polymer base material to visualize them in MRI. The purpose of this study is to evaluate the conspicuity of these mesh implants in patients treated for inguinal hernia and assessment of immediate post surgical mesh configuration.
METHOD AND MATERIALS
Approved by the ethics committee, 13 patients treated with iron-loaded mesh implants via laparoscopic or via open surgical procedure were prospectively examined beginning March 2012. MRI was conducted one day after surgery at a 1.5 Tesla scanner using three different conventional gradient echo (GRE1-3) and one T2-weighted turbospin echo (TSE) sequences. Three radiologists independently assessed mesh conspicuity and diagnostic value by the following criteria using a 4-point-scale: visual contrast-to-noise ratio, conspicuity to air artifacts, and diagnostic quality rating with respect to the mesh and to the surrounding anatomy. Mesh deformation and coverage of the hernia were visually assessed and rated using a 5-point semi-quantitative scoring system. Additionally, mesh deformation and localisation in relation to the hernia were rated. Using linear contrast and mixed models, statistical analysis was performed.
MRI successfully visualized all implants. GRE sequences clearly exhibited the mesh implants as a thick hypointense line. GRE1 was rated best (3.8; p<0.05) for diagnostic quality with respect to the mesh whereas GRE3 was suited best for combined evaluation of mesh and surrounding anatomy (2.9; p<0.05). TSE was preferred for exclusive evaluation of the anatomy (3.8; p<0.05) but insufficient in mesh delineation. Local air slightly reduced mesh delineation. Overall, in both implantation techniques, the meshes exhibited mild to moderate deformations.
The combination of iron-loaded implants and MRI facilitates mesh visualization for the first time in patients. After surgical hernia repair, mesh localization and configuration can be clearly assessed. For MRI protocol, we propose a combination of different gradient echo sequences and T2-weighted TSE sequences.
Using this new technique, MRI could become a non-invasive alternative to open surgical exploration if mesh-related complications after hernia surgery are suspected.
Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
[Show abstract][Hide abstract] ABSTRACT: Objectives:
Until today, there have been no conventional imaging methods available to visualize surgical mesh implants and related complications. In a new approach, we incorporated iron particles into polymer-based implants and visualized them by magnetic resonance imaging (MRI).After clinical approval of such implants, the purposes of this study were to evaluate the MRI conspicuity of such iron-loaded mesh implants in patients treated for inguinal hernias and to assess the immediate postsurgical mesh configuration.
Materials and methods:
Approved by the ethics committee, in this prospective cohort study, 13 patients (3 patients with bilateral hernia treatment) were surgically treated for inguinal hernia receiving iron-loaded mesh implants between March and October 2012. The implants were applied via laparoscopic technique (transabdominal preperitoneal technique; n = 8, 3 patients with bilateral hernia treatment) or via open surgical procedure (Lichtenstein surgery; n = 5). Magnetic resonance imaging was performed 1 day after the surgery at a 1.5-T scanner (Achieva; Philips, Best, The Netherlands) with a 16-channel receiver coil using 3 different gradient echo sequences (first gradient echo sequence, second gradient echo sequence, and third gradient echo sequence [GRE1-3]) and 1 T2-weighted turbo spin-echo sequence (T2wTSE). Three radiologists independently evaluated mesh conspicuity and diagnostic value with respect to different structures using a semiquantitative scoring system (1, insufficient; 2, sufficient; 3, good; 4, optimal). Mesh deformation and coverage of the hernia were visually assessed and rated using a 5-point semiquantitative scoring system. Statistical analysis was performed using mixed models and linear contrast.
All 16 implants were successfully visualized by MRI. On gradient echo sequences, the mesh is clearly delineated as a thick hypointense line. On T2wTSE, the mesh was depicted as a faint hypointense line, which was difficult to identify. The first gradient echo sequence was rated best for visual conspicuity (mean [SD], 3.8 [0.4]). T2-weighted turbo spin-echo sequence was preferred for evaluation of the surrounding anatomy (mean [SD], 3.7 [0.3]). For the combined assessment of both mesh and anatomy, GRE3 was rated best (mean [SD], 2.9 [0.7]). Local air slightly reduced mesh delineation (lowest mean [SD] rating, 2.9 [0.7] for GRE3). Overall, in both implantation techniques, the meshes exhibited mild to moderate deformations (mean [SD], 3.3 [0.4], 3.1 [0.3], and 2.8 [0.3] on average with open technique, 2.7 [0.3], 2.7 [0.2], and 2.3 [0.3] with laparoscopic technique). Coverage of the hernia was achieved in 15 of the 16 implants.
Combining iron-loaded implants and MRI, we achieved mesh visualization for the first time in patients. For MRI protocol, we propose a combination of different gradient echo sequences and T2-weighted turbo spin-echo sequences: first gradient echo sequence for mesh configuration, T2wTSE for anatomy assessment, and GRE3 for evaluation of hernia coverage and mesh localization. Using our approach, MRI could become a noninvasive alternative to open surgical exploration if mesh-related complications were suspected.
[Show abstract][Hide abstract] ABSTRACT: Purpose:
Polymer-based textile meshes for abdominal hernia treatment are invisible by conventional imaging methods, including magnetic resonance imaging (MRI). Integration of iron particles in the mesh base material allows MRI visualization of meshes. Positive-contrast susceptibility imaging (PCSI) was implemented to separate susceptibility-induced voids from proton-deficient voids. The purpose of this study was to compare PCSI with conventional gradient echo and turbo spin echo (TSE) sequences for the in vivo assessment of superparamagnetic iron oxide particle-loaded surgical meshes in an animal model.
Methods and materials:
Iron-loaded polymer meshes were implanted into the abdominal wall of 10 rabbits. At days 1, 30, and 90 after surgery, conventional gradient echo, TSE, and PCSI were performed at 1.5 T in the sagittal and axial planes. Images were scored by 2 radiologists with respect to mesh visibility, delineation of the surrounding tissue, differentiation from other structures, and overall diagnostic use, on a 4-point scale ranging from 1 (insufficient) to 4 (excellent). The results were compared using Wilcoxon signed-rank tests. The mesh shape, possible deformation or fracture, and possible mesh migration were evaluated on the different pulse sequences and compared with the results at surgery and autopsy.
The iron-loaded meshes appeared as hypointense signal voids on gradient echo sequences, as a hyperintense line on PCSI, and as a very thin dark line on TSE images. In all animals, a precise depiction of the mesh location and its spatial configuration and integrity was possible by MRI and confirmed by surgical and autopsy results. In all 4 categories and at all 3 time points of imaging, image quality scores were significantly higher for gradient echo imaging (range, 3.60-3.80) compared with PCSI (range, 3.12-3.42) and TSE (range, 1.64-1.89). At day 90, the image quality ratings of gradient echo and PCSI were comparable. In 2 cases, the complete delineation of mesh borders was impossible because of signal voids of adjacent anatomical structures, whereas PCSI helped achieve this differentiation.
In this rabbit model of iron-loaded implanted abdominal meshes, standard gradient echo imaging was best suitable to assess implant location, integrity, and configuration. In 2 of 10 animals, PCSI helped achieve a complete delineation of mesh borders.
[Show abstract][Hide abstract] ABSTRACT: Background
The aim of this study was to analyze the early postoperative outcome of esophageal cancer treated by subtotal esophageal resection, gastric interposition and either intrathoracic or cervical anastomosis in a single center study.
72 patients who received either a cervical or intrathoracic anastomosis after esophageal resection for esophageal cancer were matched by age and tumor stage. Collected data from these patients were analyzed retrospectively regarding morbidity and mortality rates.
Anastomotic leakage rate was significantly lower in the intrathoracic anastomosis group than in the cervical anastomosis group (4 of 36 patients (11%) vs. 11 of 36 patients (31%); p = 0.040). The hospital stay was significantly shorter in the intrathoracic anastomosis group compared to the cervical anastomosis group (14 (range 10–110) vs. 26 days (range 12 – 105); p = 0.012). Wound infection and temporary paresis of the recurrent laryngeal nerve occurred significantly more often in the cervical anastomosis group compared to the intrathoracic anastomosis group (28% vs. 0%; p = 0.002 and 11% vs. 0%; p = 0.046). The overall In-hospital mortality rate was 6% (4 of 72 patients) without any differences between the study groups.
The present data support the assumption that the transthoracic approach with an intrathoracic anastomosis compared to a cervical esophagogastrostomy is the safer and more beneficial procedure in patients with carcinoma of the lower and middle third of the esophagus due to a significant reduction of anastomotic leakage, wound infection, paresis of the recurrent laryngeal nerve and shorter hospital stay.
World Journal of Surgical Oncology 08/2012; 10(1):159. DOI:10.1186/1477-7819-10-159 · 1.41 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Abdominal compartment syndrome (ACS) is a life threatening condition that may affect any critically ill patient. Little is known about the recognition and management of ACS in Germany.
A questionnaire was mailed to departments of surgery and anesthesia from German hospitals with more than 450 beds.
Replies (113) were received from 222 eligible hospitals (51%). Most respondents (95%) indicated that ACS plays a role in their clinical practice. Intra-abdominal pressure (IAP) is not measured at all by 26%, while it is routinely done by 30%. IAP is mostly (94%) assessed via the intra-vesical route. Of the respondents, 41% only measure IAP in patients expected to develop ACS; 64% states that a simpler, more standardized application of IAP measurement would lead to increased use in daily clinical practice.
German anesthesiologists and surgeons are familiar with ACS. However, approximately one fourth never measures IAP, and there is considerable uncertainty regarding which patients are at risk as well as how often IAP should be measured in them.
Annals of Intensive Care 07/2012; 2 Suppl 1(Suppl 1):S7. DOI:10.1186/2110-5820-2-S1-S7 · 3.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Several decades ago, the beneficial effects of goal-directed therapy, which include decompressive laparotomy (DL) and open abdomen procedures in cases of intra-abdominal hypertension (IAH) in children, were proven in the context of closures of abdominal wall defects and large-for-size organ transplantations. Different neonatologic and pediatric disease patterns are also known to be capable of increasing intra-abdominal pressure (IAP). Nevertheless, a considerable knowledge transfer regarding such risk factors has hardly taken place. When left undetected and untreated, IAH threatens to evolve into abdominal compartment syndrome (ACS), which is accompanied by a mortality rate of up to 60% in children. Therefore, the present study looks at the recognition and knowledge of IAH/ACS among German pediatric intensivists.
In June 2010, a questionnaire was mailed to the heads of pediatric intensive care units of 205 German pediatric hospitals.
The response rate was 62%. At least one case of IAH was reported by 36% of respondents; at least one case of ACS, by 25%. Compared with adolescents, younger critically ill children appeared to develop IAH/ACS more often. Routine measurements of IAP were said to be performed by 20% of respondents. Bladder pressure was used most frequently (96%) to assess IAP. Some respondents (17%) only measured IAP in cases of organ dysfunction and failure. In 2009, the year preceding this study, 21% of respondents claimed to have performed a DL. Surgical decompression was indicated if signs of organ dysfunction were present. This was also done in cases of at least grade III IAH (IAP > 15 mmHg) without organ impairment.
Although awareness among pediatricians appears to have been increasing over the last decade, definitions and guidelines regarding the diagnosis and management of IAH/ACS are not applied uniformly. This variability could express an ever present lack of awareness and solid prospective data.
Annals of Intensive Care 07/2012; 2 Suppl 1(Suppl 1):S8. DOI:10.1186/2110-5820-2-S1-S8 · 3.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: To reduce infection rates after mesh implantation antibiotic-coated meshes were designed. The aim of the study was to analyze biocompatibility and in vitro efficiency of a modified gentamicin-supplemented polyvinylidenfluoride mesh. Twenty rats were randomized to two groups (PVDF group and Genta group). Mesh material was implanted subcutaneously. Blood samples were taken to determine the gentamicin serum concentration. Seven and 90 days after mesh implantation, animals were euthanized. The inflammatory tissue response was characterized by analyzing the foreign body granuloma. Cellular immune response was analyzed by immunohistochemical investigations. The collagen type I/III ratio was estimated by crosspolarization microscopy. In vitro agar diffusion test, suspension test, and gentamicin release were characterized. Agar diffusion and suspension test showed efficient antibiotic effects of the mesh in vitro. Serum concentrations of gentamicin showed a peak value 1 h postoperatively with a decline within the next day. The total size of the granuloma was significantly smaller in the Genta group compared to the PVDF group at both points of time. Except of a short period of increased expression of CD68 in the Genta group after 7 days, no further difference was found analyzing cellular immune response. The collagen type I/III ratio was widely constant analyzing the two mesh types without significant differences comparing both mesh materials. A significantly decreased foreign body granuloma formation compared to the pure PVDF mesh group was found. In vitro analysis showed efficient antibiotic effects of the Gentamicin supplementation compared to the pure PVDF mesh.
Journal of Biomedical Materials Research Part A 05/2012; 100(5):1195-202. DOI:10.1002/jbm.a.34066 · 3.37 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Conventional radiological methods, including magnetic resonance imaging (MRI), fail to visualize polymeric surgical mesh implants because of small thread dimensions and material characteristics. For MRI delineation of such meshes, superparamagnetic iron oxide particles (SPIOs) are integrated in the mesh polymer. Usually, if SPIOs are used as an intravenous contrast agent, they increase the R1 and R2 of adjacent protons. It can be assumed that embedding SPIOs in polymers alters their molecular dynamics. The aim of this study was to investigate the influence of SPIO integration in polymer on the relaxation of adjacent protons.
Polymer threads were placed in an agarose phantom. At 1.5 T, R1, R2, and R2* maps were calculated from multi inversion-recovery spin echo, multi-spin echo, and multi-gradient echo images, respectively. The threads were aligned parallel or orthogonal to B(0).
No impact of SPIO on proton R1 and R2 was observed. R2* was increased by the SPIO-loaded threads. R1 and R2 amplitude maps showed a magnetic susceptibility difference of 0.97 ppm/(mg SPIO/g polymer) around SPIO-loaded threads.
In contrast to SPIO in aqueous solutions, polymer-embedded SPIO do not affect proton R1 and R2. However, embedded SPIO generate strong local static magnetic field gradients. Thus, SPIO integration is suitable to control the magnetic susceptibility of polymer threads. This can be exploited to visualize implanted polymer-based meshes in MRI using R2* susceptible sequences. Because no impact on R1 and R2 of adjacent protons by SPIO embedded in mesh threads was observed, structures adjacent to implanted meshes will be observable in R1 and R2 maps.
[Show abstract][Hide abstract] ABSTRACT: For the development of a surgical mesh implant that is visible in magnetic resonance imaging (MRI), superparamagnetic iron oxides (SPIOs) are integrated into the material of the mesh. In order to get a high quality mesh regarding both mechanical and imaging properties, a narrow size distribution and homogenous spatial distribution, as well as a strong magnetization of SPIOs within the filament of the mesh are required. In this work, six different samples of SPIOs composed of a magnetite core are synthesized with and without stabilizing dodecanoic acid and analyzed using a superconducting quantum interference device (SQUID), transmission electron microscope (TEM) and a magnetic force microscope (MFM) to determine the properties that are beneficial for the assembly and imaging of the implant. These analyses show the feasibility of visualization of surgical implants with incorporated SPIOs and the influence of the agglomeration of SPIOs on their magnetization and on a homogenous spatial distribution within the polymer of the mesh.
Current pharmaceutical biotechnology 01/2012; 13(4):545-51. DOI:10.2174/138920112799436249 · 2.51 Impact Factor