A bioengineering PhD candidate from the University of Pittsburgh’s Swanson School of Engineering has been developing a 3D printed phantom head which so closely resembles a human head that it can be used to test the 7 Tesla magnetic resonance imager (7T MRI), one of the strongest clinical MRI devices in use.
Within the medical sector, a phantom is an object—usually based on an anatomical feature—which undergoes scanning or imaging processes in order to evaluate and test the performance of the devices being used. In certain cases, 3D printing is now being explored for the creation of phantom models, especially as the ability to 3D print bio-inspired materials and tissue-like materials advances.
In this case, PhD student Sossena Wood leveraged 3D printing to create a life-size and incredibly realistic head for MRI testing. Wood has been working within associate professor Tamer Ibrahim’s Radiofrequency (RF) Research Facility in developing the phantom head. Presently, she is completing her dissertation on the project, which was partly inspired by Ibrahim’s desire to have a 3D printed phantom head to test his lab’s imaging equipment.
“In the RF Research Facility, we use a whole-body 7 Tesla magnetic resonance imager (7T MRI), which is one of the strongest clinical human MRI devices in the world,” explained Ibrahim, adding that the technology does present certain challenges.
“As you move from lower to higher fields, the images produced become less uniform and localized heating becomes more prevalent,” he added. “We wanted to develop an anthropomorphic phantom head to help us better understand these issues by providing a safer way to test the imaging. We use the device to analyze, evaluate, and calibrate the MRI systems and instrumentation before testing new protocols on human subjects.”
In making the phantom head, Wood first obtained the dataset from a 3T MRI scan of a healthy male. With the dataset, the researcher segmented the head into eight tissue compartments—a detail which most phantom heads do not integrate. This preliminary computational work enabled Wood to establish a digital blueprint for the phantom model.
Next, the researcher took an MRI scan of a healthy male’s head to produce a 3D digital image which was subsequently put through CAD software to optimize and adjust the design. Once that was complete, Wood set about 3D printing the phantom head, which reportedly took three semesters to complete.
She explains: “We used a plastic developed by DSM Somos for our printing material because it allowed us to create durable and detailed parts with a similar conductivity to the human body. To help the model further mimic a real environment, we created filling ports on the prototype where we can deposit fluids that resemble various tissue types.”
The phantom head is now completely 3D printed, and Wood has assembled and prepared it for testing. What will it be used to test specifically? According to Wood it can be used to test whether certain types of implants can go into an MRI and to detect temperature rises in various tissue types depending on different RF instrumentation.
“With MR imaging, the power from the RF exposure is transformed into heat in the patient’s tissue, which can have detrimental effects on the patient’s health, especially with implants if not monitored by the scanner” said Wood.
Ibrahim added: ”With our phantom head, we can test the safety of our imaging by putting probes inside of certain regions of the head and measuring the effects.” Moving forward, the researchers hope to further adapt the 3D printed phantom with the goal of commercializing it.