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.
Results: 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.
Conclusions: 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.