ADVANCED INTELLIGENT SYSTEMS, cilt.4, sa.4, 2022 (SCI-Expanded)
Magnetic resonance imaging (MRI) scanners have recently been used for magnetic actuation of robots for minimally invasive medical operations. Due to MRI's high soft-tissue selectivity, it is possible to obtain 3D images of hard-to-reach cavities in the human body, where the wireless miniature magnetic robots powered by MRI could be employed for high-precision targeted operations, such as drug delivery, stem cell therapy, and hyperthermia. However, the state-of-the-art fast magnetic robot-tracking methods in MRI are limited above millimeter-size scale, which restricts the potential target regions inside the human body. Herein, a fast 1D projection-based MRI approach that can track magnetic particles down to 300 mu m diameter (1.17 x 10(-2) emu) is reported. The technique reduces the trackable magnetic particle size in MRI-powered navigation fivefold compared with the previous fast-tracking methods. A closed-loop MRI-powered navigation with 0.78 +/- 0.03 mm trajectory-following accuracy in millimeter-sized in vitro 2D channels and a 3D cavity setup using the tracking method is demonstrated. Furthermore, the feasibility of submillimeter magnetic robot tracking in ex vivo pig kidneys (N = 2) with a 3.6 +/- 1.1 mm accuracy is demonstrated. Such a fast submillimeter-scale mobile robot-tracking approach can unlock new opportunities in minimally invasive medical operations.