MRI-Guided Microscopic Robots Eliminate Liver Tumors

The current primary treatment modality is transarterial chemoembolization. This technique delivers chemotherapy directly into the artery supplying the liver tumor and blocks the tumor's blood supply using microcatheters, guided by X-ray. However, this method is invasive and demands highly skilled medical professionals. Now, a novel approach for treating liver tumors that uses magnet-guided microrobots in an MRI device could revolutionize interventional radiology approaches used to treat liver cancers.

The concept of injecting microscopic robots into the bloodstream for therapeutic purposes has been around for some time. Miniature robots, composed of biocompatible, magnetizable iron oxide nanoparticles and directed by an external magnetic field, can theoretically offer highly precise medical treatments. A key challenge has been that the gravitational force on these microrobots is greater than the magnetic force, affecting their navigation, especially when the target tumor lies above the injection site. While MRI machines produce a strong magnetic field, the magnetic gradients for navigation and image generation are relatively weak. Researchers at the University of Montreal Hospital Research Centre (CRCHUM, Quebec, Canada) have developed an innovative algorithm. This algorithm calculates the optimal positioning of the patient’s body within a clinical MRI to utilize gravity in conjunction with magnetic navigation forces, facilitating the movement of microrobots to arterial branches feeding the tumor and thereby conserving healthy cells.

This magnetic resonance navigation method can be implemented with an implantable catheter similar to those used in chemotherapy. Another advantage is that tumors are more clearly visible in MRI than in X-ray imaging. The researchers have created an MRI-compatible microrobot injector, assembling 'particle trains' - aggregates of magnetizable microrobots with enhanced magnetic force, making them easier to steer and detect in MRI images. This enables precise control of both the direction of the microrobot 'train' and the adequacy of the treatment dosage. As each microrobot is intended to deliver a fraction of the treatment, quantifying them is crucial for radiologists. Although this scientific advancement marks significant progress, its clinical application remains some distance away. Further, scientists must develop models to simulate blood flow, patient positioning, and magnetic field orientation. This modeling, predicting the fluid flow through vessels, will enhance the precision of microrobot transport to the target tumor, refining the accuracy of this innovative approach.

“First of all, using artificial intelligence, we need to optimize real-time navigation of the microrobots by detecting their location in the liver and also the occurrence of blockages in the hepatic artery branches feeding the tumor,” said Dr. Gilles Soulez, a researcher at the CHUM Research Centre.

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