World's first high-resolution brain developed using a 3D printer

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

Magnetic resonance imaging (MRI) is a widely used diagnostic imaging technique that is primarily used to examine the brain. MRI allows the structure and function of the brain to be examined without the use of ionising radiation. In a special variant of MRI, diffusion-weighted MRI (dMRI), the direction of the nerve fibres in the brain can also be determined. However, it is very difficult to correctly determine the direction of nerve fibres at the crossing points of nerve fibre bundles, as nerve fibres with different directions are superimposed there. In order to further improve the process and test analysis and evaluation methods, an international team developed a so-called „brain phantom“ (brain phantom) in collaboration with the Vienna University of Technology and the Medical University of Vienna, which was produced using a high-resolution 3D printing process.

Tiny cube with microchannels

Researchers from the Medical University of Vienna as MRI experts and the Vienna University of Technology as 3D printing experts worked closely with colleagues from the University of Zurich and the University Medical Centre Hamburg-Eppendorf. Back in 2017, a two-photon polymerisation printer was developed at TU Wien that enables upscaled printing. In the course of this, work was also carried out together with the Medical University of Vienna and the University of Zurich on brain phantoms as an application. The resulting patent forms the basis for the brain phantom that has now been developed and is being supervised by TU Wien's research and transfer support team.

Optically, this phantom does not have much to do with a real brain. It is much smaller and has the shape of a cube. Inside it are tiny water-filled microcannulae in the size of individual cranial nerves. The diameters of these channels are five times thinner than a human hair. In order to imitate the fine network of nerve cells in the brain, the research team led by first authors Michael Woletz (Center for Medical Physics and Biomedical Engineering, MedUni Vienna) and Franziska Chalupa-Gantner (3D Printing and Biofabrication research group, TU Wien) resorted to a rather unusual 3D printing method: two-photon polymerisation. This high-resolution method is primarily used for printing microstructures in the nano and micrometre range - not for printing three-dimensional structures in the cubic millimetre range. In order to create phantoms of a suitable size for dMRI, the researchers at TU Wien have been working on upscaling the 3D printing process and enabling the printing of larger objects with high-resolution details. The upscaled 3D printing provides the researchers with very good models that - when viewed under dMRI - make it possible to assign different nerve structures. Michael Woletz compares this approach to improving the diagnostic capabilities of dMRI with the way a mobile phone camera works: "The greatest progress in photography with mobile phone cameras is not necessarily seen in new, better lenses, but in the software that improves the images taken. It is similar with dMRI: using the newly developed brain phantom, we can adjust the analysis software much more precisely, thereby improving the quality of the measured data and reconstructing the neural architecture of the brain more accurately.

Brain phantom trains analysis software

The authentic reproduction of characteristic nerve structures in the brain is therefore important for training the dMRI „analysis software“. The use of 3D printing allows the creation of diverse and complex designs that can be modified and customised. The brain phantoms thus represent areas of the brain that generate particularly complex signals and are therefore difficult to analyse, such as crossing neural pathways. In order to calibrate the analysis software, the brain phantom is therefore examined using dMRI and the measured data is analysed as in a real brain. Thanks to 3D printing, the design of the phantoms is precisely known and the results of the analyses can be verified. Vienna University of Technology and MedUni Vienna were able to show that this works as part of their joint research work. The phantoms developed can be used to improve dMRI, which can benefit the planning of operations and research into neurodegenerative diseases such as Alzheimer's, Parkinson's and multiple sclerosis.

Despite the proof of concept, the team still faces challenges. The biggest challenge at the moment is scaling the method: „The high resolution of two-photon polymerisation makes it possible to print details in the micro- and nanometre range and is therefore very suitable for imaging cranial nerves. At the same time, however, it takes a correspondingly long time to print a cube several cubic centimetres in size with this technique," explains Chalupa-Gantner. „Therefore, we are not only aiming to develop even more complex designs, but also to further optimise the printing process itself.“

Source: https://idw-online.de/de/news830696