The new model has the potential to accelerate research into neurodegenerative diseases. A joint project between MedUni Vienna and TU Wien has developed the world’s first 3D-printed brain phantom, which is modeled after the structure of brain fibers and can be imaged using a special type of magnetic resonance imaging (dMRI).

As the research team led by MedUni Vienna and TU Wien has shown, these brain models can be used to advance research into neurodegenerative diseases such as Alzheimer’s, Parkinson’s and multiple sclerosis. The research study was published in the journal Advanced Material Technologies.

Magnetic resonance imaging (MRI) is a widely used diagnostic method used primarily to examine the brain. With the help of MRI, you can examine the structure and functions of the brain without using ionizing radiation. Diffusion-weighted MRI (dMRI), a special type of MRI, can also determine the orientation of nerve fibers in the brain. However, it is very difficult to accurately determine the direction of nerve fibers at the intersection of nerve fiber bundles because nerve fibers of different directions overlap here.

In order to further improve the process and methods of analysis and evaluation of tests, an international team collaborating with the Medical University of Vienna and the Technical University of Vienna has developed a device called “brain ghost” produced using high technology. resolution 3D printing process.

A small cube with a microchannel

Researchers from the Medical University of Vienna as MRI experts and TU Wien as 3D printing experts worked in close collaboration with colleagues from the University of Zurich and the University Medical Center Hamburg-Eppendorf. In 2017, the Vienna University of Technology developed a two-photon polymerization printer that provides advanced printing.

During this process, studies were also carried out on brain phantoms as a usage example, together with the Medical University of Vienna and the University of Zurich. The resulting patent forms the basis for the brain ghost, which is currently being developed and supervised by the research and transfer support team at TU Wien.

Visually, this ghost has little in common with a real brain. It is much smaller and cube-shaped. It contains extremely thin, water-filled microchannels the size of individual cranial nerves. The diameter of these channels is five times smaller than a human hair. To mimic the fine network of nerve cells in the brain, the research team led by first authors Michael Voletz (Centre for Medical Physics and Biomedical Engineering, MedUni Vienna) and Franziska Halupa-Gantner (Research Group 3D Printing and Biofabrication, TU Wien) used a rather unconventional method of 3D printing. : two-photon polymerization.

This high-resolution method is mainly used to print microstructures in the nanometer and micrometer range, rather than printing 3D structures in the cubic millimeter range. To create right-sized phantoms for DMRI, researchers at the Vienna University of Technology worked to scale up the 3D printing process and enable larger objects to be printed with high-resolution detail. High-scale 3D printing provides researchers with very good models that allow the assignment of different neural structures when imaged with dMRI.

Michael Voletz compares this approach to the way a cell phone camera works with the development of dMRI’s diagnostic capabilities: “We see the biggest advances in photography with cell phone cameras not necessarily in new, better lenses, but in software that improves the images taken. . It’s similar with DMRI.” “Using the newly developed brain phantom, we can fine-tune the analysis software much more precisely, thereby improving the quality of the measured data and reconstructing the neural architecture of the brain more accurately.”

Software for analysis of ghost brain training

Therefore, specific reproduction of characteristic neural structures in the brain is essential for “training” dMRI analysis software. The use of 3D printing allows the creation of diverse and complex designs that can be modified and customized. Therefore, brain phantoms show areas in the brain that generate particularly complex signals and are therefore difficult to analyze, such as the intersection of neural pathways.

To calibrate the analysis software, a brain phantom is examined with dMRI and the measured data is analyzed as in a real brain. Thanks to 3D printing, the design of the phantoms can be known precisely and the analysis results can be verified. MedUni Vienna and TU Wien have managed to show that this works as part of a joint research effort. The developed phantoms can be used to improve dMRI, which could benefit surgical planning and research into neurodegenerative diseases such as Alzheimer’s, Parkinson’s and multiple sclerosis.

Despite the proof of concept, the team still encountered problems. The biggest challenge now is to scale up the method: “The high resolution of two-photon polymerization makes it possible to print details in the micro- and nanometer range and is therefore well-suited for imaging cranial nerves. At the same time, printing a cube of several cubic centimeters using this technique is correspondingly long.” “Therefore, we are not only developing more complex designs, but also trying to further optimize the printing process.”