Diagnostic abdominal MR imaging on a prototype low-field 0.55 T scanner operating at two different gradient strengths

Chandarana, Hersh; Bagga, Barun; Huang, Chenchan; Dane, Bari; Petrocelli, Robert; Bruno, Mary; Keerthivasan, Mahesh Bharath; Grodzki, David; Block, Kai Tobias; Stoffel, David R.; Sodickson, Daniel K.

doi:10.1007/s00261-021-03234-1

Cited by 19 publications

(15 citation statements)

References 15 publications

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“…6 Although signal-tonoise ratios (SNRs) are inherently lower at low field strength, resulting in long acquisition times, diagnostic quality similar to 1.5 T can be obtained, representing a viable alternative globally. 7 The US Food and Drug Administration has recently cleared the first 80-cm wide-bore 0.55 T system for human imaging, which additionally promises improving access for obese and claustrophobic patient populations. 8 Low-field MRI improves visualization of the soft tissues near the metallic hardware, owing to the physics principle that susceptibility artifacts are proportional to the field strength.…”

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confidence: 99%

“…Compared with their ancestors, the new generation of low-field MRI systems allows the implementation of many new imaging techniques such as parallel imaging, simultaneous multislice excitation, and multispectral metal artifact reduction imaging 6 . Although signal-to-noise ratios (SNRs) are inherently lower at low field strength, resulting in long acquisition times, diagnostic quality similar to 1.5 T can be obtained, representing a viable alternative globally 7 . The US Food and Drug Administration has recently cleared the first 80-cm wide-bore 0.55 T system for human imaging, which additionally promises improving access for obese and claustrophobic patient populations 8…”

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confidence: 99%

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New-Generation Low-Field Magnetic Resonance Imaging of Hip Arthroplasty Implants Using Slice Encoding for Metal Artifact Correction

Khodarahmi

Brinkmann²,

Lin

et al. 2022

Invest Radiol

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ObjectivesDespite significant progress, artifact-free visualization of the bone and soft tissues around hip arthroplasty implants remains an unmet clinical need. New-generation low-field magnetic resonance imaging (MRI) systems now include slice encoding for metal artifact correction (SEMAC), which may result in smaller metallic artifacts and better image quality than standard-of-care 1.5 T MRI. This study aims to assess the feasibility of SEMAC on a new-generation 0.55 T system, optimize the pulse protocol parameters, and compare the results with those of a standard-of-care 1.5 T MRI.Materials and MethodsTitanium (Ti) and cobalt-chromium total hip arthroplasty implants embedded in a tissue-mimicking American Society for Testing and Materials gel phantom were evaluated using turbo spin echo, view angle tilting (VAT), and combined VAT and SEMAC (VAT + SEMAC) pulse sequences. To refine an MRI protocol at 0.55 T, the type of metal artifact reduction techniques and the effect of various pulse sequence parameters on metal artifacts were assessed through qualitative ranking of the images by 3 expert readers while taking measured spatial resolution, signal-to-noise ratios, and acquisition times into consideration. Signal-to-noise ratio efficiency and artifact size of the optimized 0.55 T protocols were compared with the 1.5 T standard and compressed-sensing SEMAC sequences.ResultsOverall, the VAT + SEMAC sequence with at least 6 SEMAC encoding steps for Ti and 9 for cobalt-chromium implants was ranked higher than other sequences for metal reduction (P < 0.05). Additional SEMAC encoding partitions did not result in further metal artifact reductions. Permitting minimal residual artifacts, low magnetic susceptibility Ti constructs may be sufficiently imaged with optimized turbo spin echo sequences obviating the need for SEMAC. In cross-platform comparison, 0.55 T acquisitions using the optimized protocols are associated with 45% to 64% smaller artifacts than 1.5 T VAT + SEMAC and VAT + compressed-sensing/SEMAC protocols at the expense of a 17% to 28% reduction in signal-to-noise ratio efficiency. B1-related artifacts are invariably smaller at 0.55 T than 1.5 T; however, artifacts related to B0 distortion, although frequently smaller, may appear as signal pileups at 0.55 T.ConclusionsOur results suggest that new-generation low-field SEMAC MRI reduces metal artifacts around hip arthroplasty implants to better advantage than current 1.5 T MRI standard of care. While the appearance of B0-related artifacts changes, reduction in B1-related artifacts plays a major role in the overall benefit of 0.55 T.

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confidence: 99%

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confidence: 99%

New-Generation Low-Field Magnetic Resonance Imaging of Hip Arthroplasty Implants Using Slice Encoding for Metal Artifact Correction

Khodarahmi

Brinkmann²,

Lin

et al. 2022

Invest Radiol

Self Cite

View full text Add to dashboard Cite

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“…All imaging was coregistered and paired axial slices were drawn from each image type. We asked the neuroradiologists to rate slices from each image type using a 5-point Likert scale [ 22 ]. Each neuroradiologist rated a total of 90 image slices and slice order was randomized.…”

Section: Methodsmentioning

confidence: 99%

“…(1 = excellent, 2 = good, 3 = average, 4 = poor, and 5 = nondiagnostic). Statistical comparisons between 3 T, real 64mT, and simulated 64mT imaging were performed using a paired sample Wilcoxon signed-rank test [ 22 ].…”

Section: Methodsmentioning

confidence: 99%

Simulated diagnostic performance of low-field MRI: Harnessing open-access datasets to evaluate novel devices

Arnold

Baldassano

Litt

et al. 2022

Magnetic Resonance Imaging

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“…This improvement may stem from advanced RF transmit technology and optimized RF pulses tailored for musculoskeletal imaging at 0.55 T. More recently, asymmetric adiabatic skewed spectral adiabatic inversion recovery RF pulses with inversion times optimized for the low field strength have been developed and successfully implemented. 56 Dixon technique-based fat suppression offers the calculation of differential MR contrasts based on the acquisition of a set of in-phase (IP) and an otherwise identical set of opposed-phase (OP) images. Various pulse sequences can be utilized, including TSE and gradient echo pulse sequences with 2-or 3-dimensional acquisition schemes.…”

Section: Fat Suppressionmentioning

confidence: 99%

Modern Low-Field MRI of the Musculoskeletal System

Khodarahmi

Keerthivasan²,

Brinkmann³

et al. 2022

Invest Radiol

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Magnetic resonance imaging (MRI) provides essential information for diagnosing and treating musculoskeletal disorders. Although most musculoskeletal MRI examinations are performed at 1.5 and 3.0 T, modern low-field MRI systems offer new opportunities for affordable MRI worldwide. In 2021, a 0.55 T modern low-field, whole-body MRI system with an 80-cm-wide bore was introduced for clinical use in the United States and Europe. Compared with current higher-field-strength MRI systems, the 0.55 T MRI system has a lower total ownership cost, including purchase price, installation, and maintenance. Although signal-to-noise ratios scale with field strength, modern signal transmission and receiver chains improve signal yield compared with older low-field magnetic resonance scanner generations. Advanced radiofrequency coils permit short echo spacing and overall compacter echo trains than previously possible. Deep learning-based advanced image reconstruction algorithms provide substantial improvements in perceived signal-to-noise ratios, contrast, and spatial resolution. Musculoskeletal tissue contrast evolutions behave differently at 0.55 T, which requires careful consideration when designing pulse sequences. Similar to other field strengths, parallel imaging and simultaneous multislice acquisition techniques are vital for efficient musculoskeletal MRI acquisitions. Pliable receiver coils with a more cost-effective design offer a path to more affordable surface coils and improve image quality. Whereas fat suppression is inherently more challenging at lower field strengths, chemical shift selective fat suppression is reliable and homogeneous with modern low-field MRI technology. Dixon-based gradient echo pulse sequences provide efficient and reliable multicontrast options, including postcontrast MRI. Metal artifact reduction MRI benefits substantially from the lower field strength, including slice encoding for metal artifact correction for effective metal artifact reduction of high-susceptibility metallic implants. Wide-bore scanner designs offer exciting opportunities for interventional MRI. This review provides an overview of the economical aspects, signal and image quality considerations, technological components and coils, musculoskeletal tissue relaxation times, and image contrast of modern low-field MRI and discusses the mainstream and new applications, challenges, and opportunities of musculoskeletal MRI.

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Diagnostic abdominal MR imaging on a prototype low-field 0.55 T scanner operating at two different gradient strengths

Cited by 19 publications

References 15 publications

New-Generation Low-Field Magnetic Resonance Imaging of Hip Arthroplasty Implants Using Slice Encoding for Metal Artifact Correction

New-Generation Low-Field Magnetic Resonance Imaging of Hip Arthroplasty Implants Using Slice Encoding for Metal Artifact Correction

Simulated diagnostic performance of low-field MRI: Harnessing open-access datasets to evaluate novel devices

Modern Low-Field MRI of the Musculoskeletal System

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