Dataset Information

A low-cost and shielding-free ultra-low-field brain MRI scanner.

ABSTRACT: Magnetic resonance imaging is a key diagnostic tool in modern healthcare, yet it can be cost-prohibitive given the high installation, maintenance and operation costs of the machinery. There are approximately seven scanners per million inhabitants and over 90% are concentrated in high-income countries. We describe an ultra-low-field brain MRI scanner that operates using a standard AC power outlet and is low cost to build. Using a permanent 0.055 Tesla Samarium-cobalt magnet and deep learning for cancellation of electromagnetic interference, it requires neither magnetic nor radiofrequency shielding cages. The scanner is compact, mobile, and acoustically quiet during scanning. We implement four standard clinical neuroimaging protocols (T1- and T2-weighted, fluid-attenuated inversion recovery like, and diffusion-weighted imaging) on this system, and demonstrate preliminary feasibility in diagnosing brain tumor and stroke. Such technology has the potential to meet clinical needs at point of care or in low and middle income countries.

SUBMITTER: Liu Y

PROVIDER: S-EPMC8671508 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature

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A low-cost and shielding-free ultra-low-field brain MRI scanner.

Liu Yilong Y Leong Alex T L ATL Zhao Yujiao Y Xiao Linfang L Mak Henry K F HKF Tsang Anderson Chun On ACO Lau Gary K K GKK Leung Gilberto K K GKK Wu Ed X EX

Nature communications 20211214 1

Magnetic resonance imaging is a key diagnostic tool in modern healthcare, yet it can be cost-prohibitive given the high installation, maintenance and operation costs of the machinery. There are approximately seven scanners per million inhabitants and over 90% are concentrated in high-income countries. We describe an ultra-low-field brain MRI scanner that operates using a standard AC power outlet and is low cost to build. Using a permanent 0.055 Tesla Samarium-cobalt magnet and deep learning for ...[more]

PMID: 34907181

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Project description:Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI systems.

Project description:Background and objectiveProgressive multifocal leukoencephalopathy (PML) is a severe, disabling infection caused by JC virus reactivation. PML-related disability complicates the MRI monitoring needed to assess treatment interventions in clinical trial or compassionate use settings. Portable ultra-low-field MRI (pULF-MRI) offers a convenient approach when such frequent imaging is needed. We evaluated the potential utility of pULF-MRI as an adjunctive tool for decreasing the burden of clinical study participation and clinical management in PML.MethodsWe examined paired high-field (HF) and pULF-MRI scans from 11 patients, aged 49 ± 15 years. pULF-MRI images with corresponding HF-MRI were coupled to depict key imaging findings of PML, including three patients with longitudinal evaluations, one with bedside pULF-MRI. The images were then independently assessed by two blinded raters, not involved in image acquisition or initial evaluations, who sequentially rated diagnostic accuracy of pULF-MRI scans compared to the HF-MRI. Longitudinal evaluations were performed for three patients, one with bedside pULF-MRI.ResultsT2-FLAIR lesions were detected with pULF-ULF in all cases when present on HF-MRI. Median sensitivity and specificity were 62% and 100%, respectively. T1WI hypointense areas showed similar performance. Focal volume loss was present in 8/11 HF-MRI scans, with sensitivity and specificity of detection by pULF-MRI of 100% and 94%, respectively. Contrast enhancement was seen in a single case on both pULF- and HF-MRI. Follow-up pULF-MRI showed lesion changes in two cases, and stable findings in one case, consistent with HF-MRI.DiscussionpULF-MRI shows promise in evaluation and monitoring of PML, showing moderate-to-high accuracy even when evaluations were unaided by HF-MRI. Our results highlight a potential application of pULF-MRI for facilitating participation in PML clinical research and more generally as a way to reduce burden of clinical management for this disabled patient population.

Dataset Information

A low-cost and shielding-free ultra-low-field brain MRI scanner.

Publications

A low-cost and shielding-free ultra-low-field brain MRI scanner.

Similar Datasets

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