Evaluating repeatability and reproducibility of in-vivo imaging using a portable Halbach-based 47mT scanner

Research Article " Evaluating repeatability and reproducibility of in-vivo imaging using a portable Halbach-based 47mT scanner" Lena et al, currently in revision by Magnetic Resonance in Medicine. For further information contact the authors. Corresponding author: Beatrice Lena E-mail: [email protected] Purpose: Low-field (LF) MRI scanners are emerging as a portable, cost-effective point-of-care solution. Their minimal infrastructure enables deployment in hospitals, remote areas, and mobile units. However, these advantages introduce unique challenges, as environmental variability may impact scanner stability. This underscores the need to evaluate the robustness of LF MRI systems. Methods: We evaluated the repeatability and reproducibility of signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and post-segmentation tissue volume in white matter (WM), grey matter (GM) and cerebrospinal fluid (CSF) in five healthy volunteers across five scan sessions. These included three sessions performed on different days in our standard scanning location, one in the intensive care unit, and one in a van, using our in-house 47 mT Halbach-based MRI scanner. Each session included a proton-density weighted scan (PDw), a T2 weighted scan (T2w), and a short inversion recovery T1 weighted scan (IR-T1w). Results: PDw scans yielded the highest SNR but the lowest WM-GM CNR, whereas T2w and IR-T1w scans showed lower SNR but higher GM-WM CNR. Intra-subject repeatability and reproducibility were strong, with only minor variations in specific metrics, such as a slight increase in noise level in PDw scan in the van. WM, GM, and CSF volumes were consistent across modalities, locations, and aligned with prior reports. Conclusion: The performance of the LF system is repeatable across time points and reproducible in different locations. Although larger clinical studies are needed, our findings establish a benchmark and emphasize the need for a rigorous evaluation of portable LF MRI.