The Clinical Utility of Magnetic Resonance Imaging According to Field Strength, Specifically Addressing the Breadth of Current State-of-the-Art Systems, Which Include 0.55 T, 1.5 T, 3 T, and 7 T

Runge, Val M.; Heverhagen, Johannes T.

doi:10.1097/rli.0000000000000824

Cited by 25 publications

(23 citation statements)

References 34 publications

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“…In this regard, there were only minor differences between the 0.55 T and 1.5 T DWI/ADC and FLAIR sequences ( Figure 3 and Figure 4 ) to the disadvantage of the 0.55 T system. Nevertheless, the advantages of the low-field MRI are lower costs for installation and maintenance (lower weight, smaller device size, no quench pipe, smaller MRI cabins) and thus for image acquisition, which in turn could increase future availability in developed economies, but especially in undeveloped areas [ 10 , 11 ].…”

Section: Discussionmentioning

confidence: 99%

Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison

Rusche

Breit

Bach

et al. 2022

JCM

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Objectives: Ischemic stroke is a leading cause of mortality and acquired disability worldwide and thus plays an enormous health-economic role. Imaging of choice is computed-tomographic (CT) or magnetic resonance imaging (MRI), especially diffusion-weighted (DW) sequences. However, MR imaging is associated with high costs and therefore has a limited availability leading to low-field-MRI techniques increasingly coming into focus. Thus, the aim of our study was to assess the potential of stroke imaging with low-field MRI. Material and Methods: A scanner comparison was performed including 27 patients (17 stroke cohort, 10 control group). For each patient, a brain scan was performed first with a 1.5T scanner and afterwards with a 0.55T scanner. Scan protocols were as identical as possible and optimized. Data analysis was performed in three steps: All DWI/ADC (apparent diffusion coefficient) and FLAIR (fluid attenuated inversion recovery) sequences underwent Likert rating with respect to image impression, resolution, noise, contrast, and diagnostic quality and were evaluated by two radiologists regarding number and localization of DWI and FLAIR lesions in a blinded fashion. Then segmentation of lesion volumes was performed by two other radiologists on DWI/ADC and FLAIR. Results: DWI/ADC lesions could be diagnosed with the same reliability by the most experienced reader in the 0.55T and 1.5T sequences (specificity 100% and sensitivity 92.9%, respectively). False positive findings did not occur. Detection of number/location of FLAIR lesions was mostly equivalent between 0.55T and 1.5T sequences. No significant difference (p = 0.789–0.104) for FLAIR resolution and contrast was observed regarding Likert scaling. For DWI/ADC noise, the 0.55T sequences were significantly superior (p < 0.026). Otherwise, the 1.5T sequences were significantly superior (p < 0.029). There was no significant difference in infarct volume and volume of infarct demarcation between the 0.55T and 1.5T sequences, when detectable. Conclusions: Low-field MRI stroke imaging at 0.55T may not be inferior to scanners with higher field strengths and thus has great potential as a low-cost alternative in future stroke diagnostics. However, there are limitations in the detection of very small infarcts. Further technical developments with follow-up studies must show whether this problem can be solved.

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Section: Discussionmentioning

confidence: 99%

Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison

Rusche

Breit

Bach

et al. 2022

JCM

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“…In UHF MRI systems, BC RF coils demonstrate strong B 1 -field nonuniformity mainly due to a shortened electromagnetic wavelength generated at a high frequency. The high electrical permittivity of the water molecules in the human body further shortens the wavelength by causing standing wave patterns [22,23]. In addition, the electrical conductivity of the tissues attenuates the electromagnetic field (EM-field) energy induced by the RF coil.…”

Section: Introductionmentioning

confidence: 99%

A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T

Seo

Chung

2022

Sensors

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Magnetic resonance imaging (MRI) systems must undergo quantitative evaluation through daily and periodic performance assessments. In general, the reference or standard radiofrequency (RF) coils for these performance assessments of 1.5 to 7.0 T MRI systems have been low-pass-type birdcage (LP-BC) RF coils. However, LP-BC RF coils are inappropriate for use as reference RF coils because of their relatively lower magnetic field (B1-field) sensitivity than other types of BC RF coils, especially in ultrahigh-field (UHF) MRI systems above 3.0 T. Herein, we propose a hybrid-type BC (Hybrid-BC) RF coil as a reference RF coil with improved B1-field sensitivity in UHF MRI system and applied it to an 11.7 T MRI system. An electromagnetic field (EM-field) analysis on the Hybrid-BC RF coil was performed to provide the proper dimensions for its use as a reference RF coil. Commercial finite difference time-domain program was used in EM-field simulation, and home-made analysis programs were used in analysis. The optimal specifications of the proposed Hybrid-BC RF coils for them to qualify as reference RF coils are proposed based on their B1+-field sensitivity under unnormalized conditions, as well as by considering their B1+-field uniformity and RF safety under normalized conditions.

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“…Phase information in SWI is used to emphasize the magnetic susceptibility differences of various compounds, such as deoxygenated blood, blood products, iron, and calcium, to provide a new source 10.3389/fnins.2022.999240 of contrast in MR (Haacke et al, 1995(Haacke et al, , 2004Reichenbach et al, 1997). SWI shows better results in higher fields than in lower fields because the signal-to-noise ratio (SNR) increases with the field strength (Hoult et al, 1986;Sarracanie and Salameh, 2020;Runge and Heverhagen, 2022), and it is easier to get the optimum contrast for veins at high fields with much shorter echo times than that at low fields (Haacke et al, 2009). Since high-field MRI machines are expensive, heavy and need pricey annual maintenance costs, low field MRI machines gain an edge by their potential to offer reduced costs and reduced footprints translating into wider accessibility.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, susceptibility-induced magnetic field gradients scale with B 0 , geometric distortion and blurring can be reduced due to the slower T2* decay at lower fields ( Osmanodja et al, 2022 ). Low fields are also gaining more momentum because of the reduced SAR and the comfort level of patients ( Stainsby et al, 2020 ; Bhat et al, 2021 ; Runge and Heverhagen, 2022 ; Wujciak, 2022 ). Furthermore, the susceptibility-based image artifacts caused by the changes in susceptibilities moving from air to tissue or by the metal implants are significantly reduced when the field strength decreases ( Ejbjerg et al, 2005 ; Campbell-Washburn et al, 2019 ).…”

Section: Introductionmentioning

confidence: 99%

“…Furthermore, the susceptibility-based image artifacts caused by the changes in susceptibilities moving from air to tissue or by the metal implants are significantly reduced when the field strength decreases ( Ejbjerg et al, 2005 ; Campbell-Washburn et al, 2019 ). Recently, studies of DWI and TOF MRI have shown the high-quality diagnostic values of low-field images ( Hori et al, 2006 ; Runge and Heverhagen, 2022 ). With the help of a high-performance gradient system, pulmonary imaging of diffuse lung disease or focal pneumonia, which has not been evaluated by MRI in the past, shows good contrast and details at the low field ( Hori et al, 2006 ).…”

Section: Introductionmentioning

confidence: 99%

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Susceptibility-weighted imaging at high-performance 0.5T magnetic resonance imaging system: Protocol considerations and experimental results

et al. 2022

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The high-performance low-field magnetic resonance imaging (MRI) system, equipped with modern hardware and contemporary imaging capabilities, has garnered interest within the MRI community in recent years. It has also been proven to have unique advantages over high-field MRI in both physical and cost aspects. However, for susceptibility weighted imaging (SWI), the low signal-to-noise ratio and the long echo time inherent at low field hinder the SWI from being applied to clinical applications. This work optimized the imaging protocol to select suitable parameters such as the values of time of echo (TE), repetition time (TR), and the flip angle (FA) of the RF pulse according to the signal simulations for low-field SWI. To improve the signal-to-noise ratio (SNR) performance, averaging multi-echo magnitude images and BM4D phase denoising were proposed. A comparison of the SWI in 0.5T and 1.5T was carried out, demonstrating the capability to identify magnetic susceptibility differences between variable tissues, especially, the blood veins. This would open the possibility to extend SWI applications in the high-performance low field MRI.

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The Clinical Utility of Magnetic Resonance Imaging According to Field Strength, Specifically Addressing the Breadth of Current State-of-the-Art Systems, Which Include 0.55 T, 1.5 T, 3 T, and 7 T

Cited by 25 publications

References 34 publications

Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison

Potential of Stroke Imaging Using a New Prototype of Low-Field MRI: A Prospective Direct 0.55 T/1.5 T Scanner Comparison

A Preliminary Study for Reference RF Coil at 11.7 T MRI: Based on Electromagnetic Field Simulation of Hybrid-BC RF Coil According to Diameter and Length at 3.0, 7.0 and 11.7 T

Susceptibility-weighted imaging at high-performance 0.5T magnetic resonance imaging system: Protocol considerations and experimental results

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