System characterization of a human-sized 3D real-time magnetic particle imaging scanner for cerebral applications

Abstract

Since the initial patent in 2001, the Magnetic Particle Imaging community has endeavored to develop a human-applicable Magnetic Particle Imaging scanner, incorporating contributions from various research fields. Here we present an improved head-sized Magnetic Particle Imaging scanner with low power consumption, operated by open-source software and characterize it with an emphasis on human safety. The focus is on the evaluation of the technical components and on phantom experiments for brain perfusion. We achieved 3D single- and multi-contrast imaging at 4 Hz frame rate. The system characterization includes sensitivity, resolution, perfusion and multi-contrast experiments as well as field measurements and sequence analysis. Images were acquired with a clinically approved tracer and within human peripheral nerve stimulation thresholds. This advanced scanner holds potential as a tomographic imager for diagnosing conditions such as ischemic stroke (different stages) or intracranial hemorrhage in environments lacking electromagnetic shielding, such as the intensive care unit.

Characterization of the clinically approved MRI tracer resotran for magnetic particle imaging in a comparison study

“…Resotran qualifies as a tracer for MPI and its deployment in preclinical trials and system characterizations (Thieben et al 2024) could positively impact an official medical approval for MPI. Furthermore, it will facilitate the process of clinical translation of MPI, even if the signal performance is surpassed by tailored MNPs.…”

“…Four types of plots are generated in figure4, each containing measurements of the four MNPs under investigation. On the top, the spectrum for 6 mT and 20 mT excitation amplitude is shown, because these amplitudes refer to a realistic range for human-sized MPI(Ozaslan et al 2022, Thieben et al 2024. We only plotted the odd harmonics, because they contain the majority of the information on the nonlinear magnetization of MNPs in a homogeneous sinusoidal excitation field (without offset fields).…”

A greedy regularized block Kaczmarz method for accelerating reconstruction in magnetic particle imaging

“…For potential clinical applications of real-time MPI, rapid sampling trajectory sequences and fast reconstruction of currently acquired raw data is important. This is especially true for long-term monitoring (Gräser et al 2019, Thieben et al 2024, monitoring of endovascular interventions (Rahmer et al 2017, Tong et al 2021, Ahlborg et al 2022, drug delivery and monitoring (Gao et al 2023), tumor detection (Huang et al 2023, Zhuo et al 2023, etc. To achieve fast reconstruction, it is important that the reconstruction speed and quality is high enough for the MPI system to run continuously.…”