A freshman student conceived and initiated a project to make anatomical 3D models directly from X-ray computer tomographic data sets, which could help students and medical professionals to understand complex bone and organ structures, and also to diagnose and research diseases. A paper and also a corresponding video by the researchers, titled "3D Printing of Preclinical X-ray Computed Tomographic Data Sets," was published in the Journal of Visualized Experiments (JoVE) this week, providing a detailed step-by-step howto for using a series of software packages to create and edit the 3D models from CT scans and showing the resulting 3D-printed models. JoVE is interesting in itself as it is an excellent PubMed-indexed scientific video journal, providing free-access to high quality videos that illustrate and explain research results.

(Photo : Evan Doney, Notre Dame University)
The software tools and 3D-printers needed to implement this process are becoming ever more inexpensive and easy to use.

The idea for the project, which was initiated in early 2012, came from then-freshman student Evan Doney, who worked at the laboratory of W. Matthew Leevy, research assistant professor at the Notre Dame Integrated Imaging Facility. "It's a very clever idea," Leevy says. "He did a lot of it independently. He figured out how to convert the tomographic data to a surface map for editing and subsequent 3D printing."

The paper concludes that with proper data collection, surface rendering, and stereolithographic editing, it is now possible and inexpensive to rapidly produce detailed skeletal and soft tissue structures from X-ray CT data. The translation of pre-clinical 3D data to a physical object that is an exact copy of the test subject is a powerful tool for visualization and communication, especially for relating imaging research to students, or those in other fields.

Just last month we broke the story about the first surgery in the U.S. using a 3D-printed skull implant, which was made by using data from precise X-ray CT scans. The technique demonstrated in the current paper is thus not a new idea or process, but is already developed and used since several years, and at the high-end even matured sufficiently to be FDA approved for the production of custom-made human implants, like the cranial implant made by the company Oxford Performance Materials employing their high-performance polymer material PEKK and an EOS laser sintering machine. What is new though is that the software tools and 3D-printers needed to implement this process are becoming ever more inexpensive and easy to use, to the point where students in a standard research environment can now teach themselves and use available tools to do it.

The HOWTO instructions for using the software packages are just a few pages long, which illustrates how simple it became to accomplish advanced medical and manufacturing procedures -- this exact task of replicating anatomical structures was very time consuming and expensive until now. Since this trend will increase available skills, reduce costs and lead to higher research and development output -- essentially describing vastly higher productivity in this and many other areas -- it can only be a good thing!

(Photo : Evan Doney, Notre Dame University)
3D printed models of the lungs and skeletal features of a rat X-ray CT data set. Objects were printed using a ProJet HD 3000 (left), Shapeways Inc. (Center) or a Makerbot Replicator (right). The scale bar denotes 2 cm. Note that the scale bar in panel C is smaller than that of A and B, which reflects that in some cases the Makerbot must print an enlarged object in order to output sufficient detail.

"Our project with 3-D printing is part of a broader story about 3-D printing in general," Leevy says, adding that the work has spawned several more ideas and opportunities, such as providing inexpensive models for anatomy students. "There's a market for these bones, both from animals and from humans, and we can create them at incredibly low cost. We're going to explore a lot of these markets."

A clinical collaborator, Dr. Douglas Liepert from Allied Physicians of Michiana, is enabling the researchers to print non-identifiable human data, expanding the possibilities. "Not only can we print bone structure, but we're starting to collect patient data and print out the anatomical structure of patients with different disease states to aid doctors in surgical preparation," Leevy says.

The initial project used X-ray CT data sets from a living Lobund-Wistar rat and from the preserved skull of a New Zealand White Rabbit. Coauthors of the article with Doney, Leevy, and Ravosa are Lauren Krumdick, Justin Diener, Connor Wathen, Sarah Chapman, Jeremiah Scott and Tony Van Avermaete, all of Notre Dame, and Brian Stamile of the 3-D printing companyMakerBot Industries LLC.