Mayo Clinic’s 3D Anatomic Modeling Laboratory is inventing how to use 3D printing for surgical planning and instruction. People undergoing new, uncommon or complex surgeries at Mayo Clinic may benefit from access to the clinic’s expertise in 3D anatomic models. The models the lab builds also helps with patient and medical education.
Starting around 2003, Dr. Jonathan Morris M.D., a radiologist, with colleague Dr. Jane Matsumoto M.D., a pediatric radiologist, began exploring how to communicate the detailed, complex information contained in MRIs, X-Rays, and CAT scans (see page 59.) Manufacturing Engineering discussed the successes and challenges in this application of 3D printing.
Manufacturing Engineering: We had a chance to discuss at great length the opportunities that 3D printing brought to Mayo Clinic, and how your group is going to expand in 2020. Yet, challenges must remain. Once you have done something, it’s inevitable to find better ways of doing it and the bottlenecks that exist. What are the challenges you face?
Dr. Jonathan Morris M.D.: One is segmentation.
ME: So, for our readers, segmentation is the process of interpreting data to create separate but complete models of bone structures, veins and arteries, organs and other objects, like tumors, that are in a human body.
Morris: Yes, and the time from when a CT scan has been acquired to the time you get a model is still lengthy. Most segmentation algorithms that exist are based on density of the CT scan, or signal intensity of an MRI scan, and they are not anatomically based. They do not have anything smart about them. So, we end up spending a lot of time to get that segmentation, drawing a lot of lines around objects. That could be a lost faster.
It all begins with the acquisition of the radiology studies. That is, creating radiology studies specifically for creating 3D printed models, with segmentation in mind. That could lead to getting a scan that takes less time to segment. [But instead] you are putting the patient in the position of being in the operating room instead of being in the scanner.
And then [another challenge] is creating segmentation software that is more radiology friendly, more physician friendly. Most of the software, [use] things like inverted triangles, meshes, and tools for fixing meshes. These are used for segmentation, but those are not terms that physicians are used to working with. As a result, many people early in the industry, they just learned how to do it all.
But, if you say, “We are going to scale this to the entire country, to where we are going to get reimbursed for a 3D printed model that is coming from a radiology scan,” well, that [software] is going to have to live where the radiologist lives. In a tool set that the radiologist uses.
We [at the Mayo 3D Anatomic Modeling Laboratory] use Materialise. It is FDA approved, it is fantastic. It is inside of Siemens software, but other companies, like GE, as well as Philips, Siemens, Canon are working on [creating that kind of software] in their radiology software. So that you can go from a radiology software package, which is embedded in medicine, into a 3D printer.
So, that segmentation bottleneck is being solved, but it is a ways out. For every anatomy, for every pathology.
ME: What are some new techniques you think could help?
Morris: I think some of [part of] the solution is that we are creating some artificial intelligence or machine learning algorithms that take all of the data that we have segmented and start to build algorithms where the computer can do a lot of this themselves.
ME: Are there challenges with the 3D printing equipment itself?
Morris: There is a challenge with reliability of the printers. We have multiple different types of printers that we use. We have polymer printers, powder printers, filament based printers. And they all do something unique. Each one of them has a different level of reliability and each company has a different level of service that they can offer.
When a printer does go down, getting it up and running has been a challenge. That is why we have built out our own internal infrastructure. We had to do it, because we had to keep our printers up and running. We are not like an automotive company, buy five printers and if two are down, that is OK because we have extra capacity. A lot of people using this are buying more than what they need because they know there is going to be a certain down time. Why? Because [these machines] don’t have that Six Sigma-level of reliability like say a milling machine might have. So, increased reliability of printers is definitely a challenge.
ME: One can imagine speed of printing might also be on your mind.
Morris: To get to a multicolored, multi-material pelvis of an adult [for example], with a tumor and a blood vessels, it takes about 72 hours to print. That is too long for us. So the printer time will have to come down. [Along with that], the ability to do faster post-processing with better support material removal. With water soluble support materials that cross into that multi-material, multi-color printer range—where you can put the model in [water] and soak away the support material. That would be great, because we spend a lot of time removing support materials.
ME: Are regulations surrounding 3D printing a challenge for what you do?
Morris: We have had to create a national infrastructure that tackles the regulatory environment. We have been working with the FDA, who have been fantastic partners to work with. Sometimes the FDA gets a bad rap, but I would say in our community of 3D printing, the FDA has been fantastic to work with.
ME: It might be that many of the regulatory issues involves asking the right question.
Morris: Some of the questions include what is the regulatory pathway, what is minimal risk, what is covered under the scope of medical practice, and what you should do to sterilize Class 2 medical devices, manufactured on site. We have never been capable of that before in any large scale way – it has all been smaller scale. Now there are more people doing [3D printing.] All 20 of the top hospitals in the US are doing [3D printing for surgical planning.] And more people are building out the capacity to do it. Because in reality, if you have radiologist software that can create an STL file, and access to a low cost printer, you are in the game.
So, some of the questions that must be answered include: How should that be governed? Who should govern it or regulate it? Who should come and certify us?
This is already true for our CT scanners, our mammography unit, or MRI. They all have to be American College of Radiology certified that they do what they say they do. So, what governing body certifies this? None.
Somebody at some point is going to regulate this. Not just from the FDA standpoint, but from the practice of medicine standpoint to make sure that if you are manufacturing in a hospital that you are indeed adhering to certain protocols, adhering to certain quality control systems.
ME: This is such a new field, it might be easy to imagine that finding the right people with any kind of experience is a challenge.
Morris: [There is the] challenge of hiring people. We have hired two biomedical engineers, two going on three, into a clinical department. We proved to the institution that this has significant value to patient care. And there are certain indications that we are saving money at the same that we are doing patient care. Because they have to approve these full time equivalents (FTEs) of people working in a clinical department, that are not generating clinical revenue in the traditional model.
When an institution starts introducing these other people into the system in a non-traditional revenue model, it must have leaders that have a big picture point of view. The institution needs leaders that sees the value, in certain indications, of having engineers in the clinical departments. That is another challenge.