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A Prototype Hybrid 3D Printed Training Model for CT-Guided Spinal Pain Management Injections 2013

Category Interventional Ramin Javan
Linda Gray
Peter Kranz
David Enterline
Purpose To design an anatomically accurate customizable physical three-dimensional (3D) model of the lumbosacral spine from computed tomography (CT) data utilizing emerging 3D printing technologies. Materials & Methods Images from a CT of the lumbosacral spine was used to three-dimensionally reconstruct the osseous anatomy. Materialise Mimics 10.0 was used for performing the initial 3D reconstruction, after manually perfecting the segmentation of the bony anatomy on thin slices of the scan where needed. This 3D model was exported in STL format and then imported in Autodesk 3D Studio Max 9.0, where the intricate nerve roots, the spinal cord and the intervertebral discs were added. Subsequently 3D printing was performed through commercially available services utilizing rapid prototyping technology. Gypsum-based material was used for the bony anatomy with minimum detail of 0.8 mm and rubber-like material for the neural anatomy with minimum detail of 0.3 mm. The intervertebral discs were created using low-cost commercially available platinum cure silicone rubber by simple molding/casting techniques. The assembled model was then embedded into highly concentrated gelatin solution within a container, which was subsequently placed in cold temperature to allow for congealing, simulating soft tissues. Use of gelatin allows for repeated use considering the need for multiple needle entries through the simulated soft tissues. Alternatively, polyvinyl alcohol crygoel after 2 freeze/thaw cycles can be used as a permanent representative of the surrounding soft tissues. Results A realistic customizable physical model of the lumbosacral spine was created with intricate detail for the specific use of teaching CT-guided spinal pain management procedures. Varying degrees of facet and sacroiliac arthropathy was incorporated in the model. Since gypsum material is calcium-based, the osseous anatomy is radiodense and therefore suitable for use in CT phantoms. Nerve root, facet joint, epidural and sacroiliac joint blocks can be practiced on the model. The necessary freeware or commercial software and the available options for acquiring 3D models as well as the possibly of obtaining low-price desktop 3D printers are discussed. The new possibilities that 3D printing has created for neuroradiologists, including multimaterial capability, are also briefly discussed. Conclusion CT-guided periradicular and facet joint infiltrations can be challenging for trainees. Practicing on actual patients or animal models raises ethical concerns. Radiation exposure to patients remains a priority at all times and prior training in needle placement may minimize this phenomenon. Furthermore, ACGME core competency requires training programs to be creative in providing learning experiences, e.g. utilizing simulation techniques that also allow for objective assessment of trainees. The developed 3D printed model can further be customized by incorporating pathologic conditions from actual patient data, such as vertebral body compression deformity for vertebroplasties, vertebral body lesions for biopsies, synovial cysts for aspirations and possibly for simulating discography and blood patching. Neuroradiologists can take a leading role in taking advantage of the evolving 3D printing technologies in creating numerous customizable tools for teaching interventional procedures or complex anatomy, assisting in surgical planning, or for patient education or consenting. References Aguirre DA, Bermudez S, Diaz OM. "Spinal CT-guided interventional procedures for management of chronic back pain." J Vasc Interv Radiol. 2005 May;16(5):689-97. Bellingham GA, Peng PW. "A low-cost ultrasound phantom of the lumbosacral spine." Reg Anesth Pain Med. 2010 May-Jun;35(3):290-3. Gangi A, Dietemann JL, Mortazavi R, Pfleger D, Kauff C, Roy C. "CT-guided interventional procedures for pain management in the lumbosacral spine." Radiographics. 1998 May-Jun;18(3):621-33. Gossner J. "A simple training tool for CT-guided spinal pain management." Diagn Interv Radiol. 2011 Dec;17(4):381-3. Epub 2010 Dec 9. i.Materialise.com. <http://www.i.materialise.com>, Accessed November 9, 2012. Kranz PG, Gray L, Taylor JN. "CT-guided epidural blood patching of directly observed or potential leak sites for the targeted treatment of spontaneous intracranial hypotension." AJNR Am J Neuroradiol. 2011 May;32(5):832-8. Epub 2011 Feb 24. Li JW, Karmakar MK, Li X, Kwok WH, Ngan Kee WD. "Gelatin-agar lumbosacral spine phantom: a simple model for learning the basic skills required to perform real-time sonographically guided central neuraxial blocks." J Ultrasound Med. 2011 Feb;30(2):263-72. Torres K, Staśkiewicz G, Śnieżyński M, Drop A, Maciejewski R. "Application of rapid prototyping techniques for modelling of anatomical structures in medical training and education." Folia Morphol. 2011 Feb;70(1):1-4.