Real-time tracking of moving micro-objects deep in the tissue demonstrated for the first time
Physics that gets under your skin
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Due to modern advances in medicine ever smaller objects are moved through the human body: nanotherapeutics, micro-implants, mini-catheters and tiny medical instruments. The next generation of minimally invasive microsurgery will enable small micro robots to move with their own drive through the body and through the tissue to transport substances and micro-objects. Therefore, new methods must be developed to locate these micro-objects precisely and to monitor their movement. Conventional methods such as ultrasound, X-ray or magnetic resonance imaging (MRI) fail either due to insufficient resolution or due to long-term damage from radioactivity or high magnetic fields.

Visional minimal invasive microsurgery - with the first-time real-time tracking of mobile micro-objects deep in the tissue, a decisive step has been taken.
Science Picture Co / Alamy Stock Photo
Prof. Oliver G. Schmidt and Dr. Mariana Medina Sanchez from the Leibniz Institute for Solid State and Materials Research Dresden (IFW) and PhD student Azaam Aziz succeeded with a decisive step here. They were able to track the movement of individual micro-objects below centimeter-thick tissue in real time. They used the so-called multispectral optoacoustic tomography (MSOT). This technique combines the advantages of ultrasound imaging in terms of depth and resolution with the possibilities of optical methods to map molecular structures. This allows them to clearly distinguish spectral signatures of the artificial micro-objects from those of the tissue molecules. For the investigation, the micro-objects were coated with gold nanorods. By this trick, the contrast of the signal could be significantly improved. This made it possible for the first time to track microstructures and system components moving deeply in tissue.