Dr. Hillary Mullan, a second-year neurology resident at NYU Langone Medical Center, shares her experience building anatomical models with 3D printers and the benefits of the technology in the medical field.
Hillary Mullan, MD, spent more time than most kids with neurologists during her childhood. “I had absence seizures as a kid, so I became very familiar with doctors,” recalled the second-year neurology resident at NYU Langone Medical Center in New York City.
“Overall, for me going to see my neurologist was a pretty positive experience. I was very interested in looking at the EEGs. Back then, they were done on this long roll of paper, so we'd take it home and I would flip through it and try to figure out where the seizure was. Of course, as a 6- or 7-year-old kid, you have no idea. But I was curious, and that curiosity was something you never really got away from, and it drew me to this point.”
As is often the case, the absence seizures gradually went away as she grew up, but Dr. Mullan's fascination with the brain remained. She also nurtured an ongoing love of art, although she had no formal training in the field.
“My art was purely hobby-based—for example, I really enjoyed making paper art, taking an X-Acto knife and cutting out various shapes,” she said. “During medical school, I made anatomical hearts that I was able to get published in an online medical humanities journal, and I did a couple of neurons too. But it was mostly just a stress relief hobby.”
Then, in her first year at the University of Massachusetts Medical School, she was introduced to 3D printing. “Our anatomy lab had access to a 3D printer, and one of the anatomy lab directors, Yasmin Carter, PhD, was interested in doing a project to create a model of the female pelvis,” Dr. Mullan said. “It's a very complicated area to dissect, and visualization of the structures isn't good through dissection, so the idea was to create an educational model to illustrate the spatial relationships between structures.”
Despite having no background in graphic design or engineering, Dr. Mullan was fascinated and eagerly volunteered to take on the project. With Dr. Carter, an assistant professor of translational anatomy and founder of the 3D Anatomy Innovations Lab, she spent the summer between her first and second years of medical school building the model.
“Doing technical and engineering design like this was very new to me. But I was very curious and had heard a lot about 3D printing, and it seemed like a unique skill set to have,” she said. “I had done some reading on the uses of it, and it seemed like a valuable technology to invest my time in—both its applications and the nitty-gritty of how it can actually be used to create structures, applications for drug development and prosthetics, and so on.”
The project involved extensive review of 2D anatomical atlases, as well as examining cadaver materials and MRI imaging of the musculature. “I used graphic structural software to draw the various components of the pelvic anatomy and put them all together. It was a tremendously challenging process,” she said. “I ended up importing some of the 2D images into mechanical engineering software and drawing the structures based on that. The software is set up so you can start with a sphere or other 3D shape and then use the tools within the software to sculpt the shape, making it more flat like a muscle, for example. I found pelvic bones online that someone else had created and imported those into the software.”
Perhaps the most difficult aspect of the task was that the software she used (Fusion 360 and MakerBot) is primarily designed for non-organic shapes like squares or boxes, or plates that you might put a screw in.
“When you think of the anatomy of the human body, there are a lot of complex curves and angles that are not simple geometry,” she said. “It's a very tedious process to adapt the software to account for that. Each shape is made of a bunch of lines and joints. What you end up doing with the software is, to get the shape you want, you select different vertices and then drag them out or push them in. It's kind of like sculpting with clay, only on a computer screen. This was a few years ago so there are more efficient ways to do it now. For example, there is now software available that lets you select the vasculature more easily than having to draw it yourself. You can select for a certain intensity of color, so using CT images with contrast can light up the vessels.”
Besides the software and design challenges, the hardware of the 3D printer itself taught Dr. Mullan an entirely new set of skills. “They can be very finicky. There's a lot that can go wrong,” she said. “You have to learn how to adjust the temperature settings and how to troubleshoot when it's not working. The printer I was using is similar to an inkjet printer, but instead of ink coming out of the nozzle, it's plastic, and the nozzle moves around the build plate, stacking the plastic on top of itself. The model is built within a plastic scaffold, so if you have sections that are very narrow, the build is supported by this additional scaffold as the printer prints it. You have to select the right settings for the scaffold, so that it supports your structure as it's printing, but at the same time the scaffold can't leave residual material on the model when you take it off. And of course, with plastic, the whole purpose is that it hardens, so sometimes the nozzle gets clogged.”
But the summer spent fiddling with finicky plastic, clogged nozzles, and design adaptations paid off: The project was a tremendous success and earned Dr. Mullan the Massachusetts Medical Society's 2019 Technology Award. She has since shared the model with a physical therapy program, which plans to use it in teaching pelvic anatomy. It was also used to supplement cadaveric dissection in the school's first-year anatomy course, and she's shared models with the obstetrics and gynecology and urologic gynecology departments at the medical school, for pilot use in their anatomy education lectures. “This really gave me a lot of self-satisfaction and is a project I'm very proud of,” Dr. Mullan said.
Despite her early interest in neurology as a child, and an undergraduate degree in neuroscience and biology, Dr. Mullan did briefly toy with the idea of pursuing other medical specialties. “Ultimately, I did end up returning to neurology. I love how important the physical exam is. I love the importance of the history and talking with patients,” she said. “I'm also fascinated with the anatomy and wiring of the nervous system, and the visual component, with how much we learn from the MRI and CT scans.”
While in residency, her opportunities to pursue 3D printing and model design have been more limited, but she is excited about its potential for medical education. “It's particularly relevant to neurology because so much of how we understand diseases or treatments depends upon our understanding of this very complicated anatomy,” she said. “One of the great things about 3D printing is that a number of models are freely available online that anyone can download and print, so I've been working on creating a little library of these models. There's a brainstem that I found and printed, and a number of models of skulls, and of the inner ear, that I've also found and printed. I think that understanding the anatomy of the nervous system is so important in neurology and having 3D models can really help as far as visualizing the spatial relationships between different structures: the vasculature, the brain, the bones in the spinal cord.”
But the models she has seen online are relatively simple for the most part, and Dr. Mullan has a bigger vision. “There are several different structures within the brain, and typically the models available will show you only the surface of the brain. What I would like to develop is a model that you can ‘take apart’ and compare with a CT scan or an MRI, to better understand where things are located,” she said. “So much of our understanding of stroke, for example, revolves around understanding the relationships between the vasculature and the parts of the brain supplied by the different vessels. I would love to make a complete model of what the normal vasculature of the brain looks like.”
Ultimately, she envisions creating a comprehensive library of neurology models for medical education. “Commercially available models can be very expensive,” she said. “I'm very fortunate that NYU has access to a 3D printer that we can all use for free; the cost-effectiveness of these models and your ability to share them worldwide with anyone is a unique advantage compared with just purchasing a skull model on Amazon. All these models are basically computer files, so if we create a model here in New York, someone on the other side of the world can learn from it. This is particularly important when it comes to the treatment of rare anatomical abnormalities or rare diseases.”
To build her skill set, she is also printing models designed by others, such as from the libraries of the National Institutes of Health. “It's not like you always have to reinvent the wheel,” Dr. Mullan said. “I've mostly been adapting these models to develop a library for the residents and medical students here. They think it's cool, but I haven't completely turned them away from the PowerPoint slides yet. This is so much cooler, though! It's something you can hold, turn, examine from all sides.”
Dr. Mullan enthuses about the many potential applications for 3D printing in medicine. “There's prosthetics, surgery, and now some drug companies are working on 3D printed pills in order to modify drug kinetics,” she said. “These pills are more porous than regularly made pills and dissolve instantly in your mouth with water, which is nice for people who have trouble swallowing pills.”
In fact, the first Food and Drug Administration-approved drug made by a 3D printer was an epilepsy drug—levetiracetam (Spritam).
As a second-year neurology resident, Dr. Mullan will soon choose a subspecialty focus and possibly a fellowship, but she confesses that she remains undecided. There's one factor she is sure of, however: “It's important for me to pursue a career that incorporates both clinical and non-clinical aspects, such as partnering with others on these 3D models and being involved in medical education,” she said. “Working on these models has really kindled my interest in teaching, because of how much my own knowledge was enhanced by the work. It really helped me with the visualization process. Also, medicine can be a very trying career in a lot of ways, and arts and creative expression has been an outlet for a lot of my stress.”
Your message has been successfully sent to your colleague.
Vol. 22, Issue 18 - p. 1-22
Your message has been successfully sent to your colleague.
This website uses cookies. By continuing to use this website you are giving consent to cookies being used. For information on cookies and how you can disable them visit our Privacy and Cookie Policy.