Research Article: 3D printing of surgical hernia meshes impregnated with contrast agents: in vitro proof of concept with imaging characteristics on computed tomography

Date Published: December 7, 2018

Publisher: Springer International Publishing

Author(s): David H. Ballard, Udayabhanu Jammalamadaka, Karthik Tappa, Jeffery A. Weisman, Christen J. Boyer, Jonathan Steven Alexander, Pamela K. Woodard.

http://doi.org/10.1186/s41205-018-0037-4

Abstract

Selected medical implants and other 3D printed constructs could potentially benefit from the ability to incorporate contrast agents into their structure. The purpose of the present study is to create 3D printed surgical meshes impregnated with iodinated, gadolinium, and barium contrast agents and characterize their computed tomography (CT) imaging characteristics. Commercial fused deposition layering 3D printing was used to construct surgical meshes impregnated with imaging contrast agents in an in vitro model. Polycaprolactone (PCL) meshes were printed containing iodinated, gadolinium, or barium contrast; control PCL meshes without contrast were also fabricated. The three different contrast agents were mixed with PCL powder and directly loaded into the 3D printer. CT images of the three contrast-containing meshes and the control meshes were acquired and analyzed using small elliptical regions of interest to record the Hounsfield units (HU) of each mesh. Subsequently, to test their solubility and sustainability, the contrast-containing meshes were placed in a 37 °C agar solution for 7 days and imaged by CT at days 1, 3 and 7.

All 3D printed meshes were visible on CT. Iodinated contrast meshes had the highest attenuation (2528 mean HU), significantly higher than both and gadolinium (1178 mean HU) and barium (592 mean HU) containing meshes. Only barium meshes sustained their visibility in the agar solution; the iodine and gadolinium meshes were poorly perceptible and had significantly lower mean HU compared to their pre-agar solution imaging, with iodine and gadolinium present in the adjacent agar at day 7 CT.

3D prints embedded with contrast materials through this method displayed excellent visibility on CT; however, only barium mesh maintained visibility after 7 days incubation on agar at human body temperature. This method of 3D printing with barium may have potential applications in a variety of highly personalized and CT visible medical devices.

Partial Text

Three-dimensional (3D) printing has had progressively more uses in medicine, expanding from anatomic models and surgical guides to implants and imaging phantoms [1]. Bioactive 3D printing has been used to impregnate drugs, hormones, and other substances into models, instruments, and implants, including surgical meshes [1–5]. Iodine has been successfully incorporated into 3D printed constructs and imaged with CT [6].

Commercial fused deposition layering 3D printing was used to create surgical meshes infused with imaging contrast agents. Computer-aided design files were generated in the shape of surgical meshes. These designs were manufactured using a Hyrel System 30 M 3D printer (Hyrel 3D, Norcross, GA). Three different contrast agents were used to impregnate the mesh structure including barium (barium sulfate powder; Sigma-Aldrich, St. Louis, MO), iodinated contrast (Optiray 350 [loversol], Mallinckrodt Inc., St. Louis, MO), and a gadolinium-based contrast medium (Dotarem [gadoterate meglumine]; Guerbet LLC, Bloomington, IN); control meshes without these contrast additives were also fabricated. The two commercial intravenous contrast agents (Optiray 350 and Dotarem) were selected based on the convenience and availability of these agents, which are commonly used.

All contrast-containing 3D printed meshes were visible on CT (Fig. 1), each showing mean attenuation greater than 500 HU. Iodinated contrast displayed a mean HU of 2529 + 426, gadolinium contrast displayed mean HU of 1178 + 259, barium displayed mean HU of 592 + 186, and control 3D prints displayed mean HU of − 378 + 122 (Table 1). The iodinated contrast-containing 3D printed mesh had significantly higher attenuation values compared to all other meshes and gadolinium contrast-containing 3D printed mesh had significantly higher attenuation values compared to the barium and the control mesh (Table 1).Fig. 1a Source CT image of iodinated contrast containing 3D printed mesh. b Coronal reconstructions depicting the small regions of interests used to analyze the mean Hounsfield units for each mesh. The barium mesh (top; purple region of interest) and iodinated contrast mesh (bottom; blue region of interest) are illustrated. c Maximum intensity project coronal reconstruction (c) of the three different contrast-impregnated polycaprolactone 3D printed meshes along with the control polycaprolactone 3D printed meshTable 1Mean Hounsfield units of the three contrast-containing mesh-types in comparison to each other and the control meshes3D Printed MeshesMean HU (± SD)Significantly higher attenuation compared to other meshesp-valueIodinated contrast-containing (n = 2)2529 ± 426Greater than gadolinium, barium, and control< 0.0001, < 0.0001, < 0.0001Gadolinium contrast-containing (n = 1)1178 ± 259Greater than barium and control< 0.0001, < 0.0001Barium (n = 2)592 ± 186Greater than control< 0.0001Control (n = 2)− 378 ± 122NoneNot applicableHU Hounsfield unitsSD Standard deviation In the present study, we describe fused deposition layering 3D printing as a process for impregnating contrast materials into 3D printed objects, with the proof-of-concept focusing on surgical mesh. Excellent visibility was demonstrated for CT imaging using all three contrast agents; however, contrast stability over time was demonstrated only with the barium infused mesh. The fused deposition layering 3D printing process described in the present study can potentially be applied for developing medical implants, with contrast in all layers – or all but the most external layers, for additional contrast-material containment. Moreover, contrast-impregnated fused deposition layering 3D printing can be used to create anatomic models to be CT scanned for pre-procedural planning, for image-guided therapies, or as phantoms. This study describes a novel method to incorporate contrast materials into 3D printed constructs using a commercial fused deposition modeling printer. PCL was used as the base material along with barium powder and commercial liquid iodinated and gadolinium intravenous contrast agents. 3D printed meshes infused with contrast materials were highly visible on CT, with mesh impregnated with barium demonstrating stability over time at body temperature. The 3D printing technique described in this study may have applications in a variety of future 3D printed constructs.   Source: http://doi.org/10.1186/s41205-018-0037-4

 

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