Ljungberg Emil, Padormo Francesco, Poorman Megan, Clemensson Petter, Bourke Niall, Evans John C, Gholam James, Vavasour Irene, Kollind Shannon H, Lafayette Samson L, Bennallick Carly, Donald Kirsten A, Bradford Layla E, Lena Beatrice, Vokhiwa Maclean, Shama Talat, Siew Jasmine, Sekoli Lydia, van Rensburg Jeanne, Pepper Michael S, Khan Amna, Madhwani Akber, Banda Frank A, Mwila Mwila L, Cassidy Adam R, Moabi Kebaiphe, Sephi Dolly, Boakye Richard A, Ae-Ngibise Kenneth A, Asante Kwaku P, Hollander William J, Karaulanov Todor, Williams Steven C R, Deoni Sean
Department of Medical Radiation Physics, Lund University, Lund, Sweden.
Department of Neuroimaging, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
Hum Brain Mapp. 2025 Jun 1;46(8):e70217. doi: 10.1002/hbm.70217.
The lower infrastructure requirements of portable ultra-low field MRI (ULF-MRI) systems have enabled their use in diverse settings such as intensive care units and remote medical facilities. The UNITY Project is an international neuroimaging network harnessing this technology, deploying portable ULF-MRI systems globally to expand access to MRI for studies into brain development. Given the wide range of environments where ULF-MRI systems may operate, there are external factors that might influence image quality. This work aims to introduce the quality control (QC) framework used by the UNITY Project to investigate how robust the systems are and how QC metrics compare between sites and over time. We present a QC framework using a commercially available phantom, scanned with 64 mT portable MRI systems at 17 sites across 12 countries on four continents. Using automated, open-source analysis tools, we quantify signal-to-noise, image contrast, and geometric distortions. Our results demonstrated that the image quality is robust to the varying operational environment, for example, electromagnetic noise interference and temperature. The Larmor frequency was significantly correlated to room temperature, as was image noise and contrast. Image distortions were less than 2.5 mm, with high robustness over time. Similar to studies at higher field, we found that changes in pulse sequence parameters from software updates had an impact on QC metrics. This study demonstrates that portable ULF-MRI systems can be deployed in a variety of environments for multi-center neuroimaging studies and produce robust results.
便携式超低场磁共振成像（ULF-MRI）系统对基础设施的要求较低，这使得它们能够在重症监护病房和偏远医疗设施等多种环境中使用。“统一项目”是一个国际神经成像网络，利用这项技术，在全球范围内部署便携式ULF-MRI系统，以扩大对用于脑发育研究的MRI的获取途径。鉴于ULF-MRI系统可能运行的环境范围广泛，存在一些可能影响图像质量的外部因素。这项工作旨在介绍“统一项目”使用的质量控制（QC）框架，以研究这些系统的稳健性以及QC指标在不同地点和不同时间之间的比较情况。我们提出了一个QC框架，使用一个商用体模，在四大洲12个国家的17个地点，用64 mT的便携式MRI系统进行扫描。使用自动化的开源分析工具，我们对信噪比、图像对比度和几何畸变进行量化。我们的结果表明，图像质量对不同的运行环境具有稳健性，例如电磁噪声干扰和温度。拉莫尔频率与室温显著相关，图像噪声和对比度也是如此。图像畸变小于2.5毫米，且随时间具有高稳健性。与在更高场强下的研究类似，我们发现软件更新导致的脉冲序列参数变化对QC指标有影响。这项研究表明，便携式ULF-MRI系统可以部署在各种环境中用于多中心神经成像研究，并产生稳健的结果。
