A perturbation approach for ultrafast calculation of RF field enhancements near medical implants in MRI

Stijnman, Peter R. S.; Steensma, Bart R.; Berg, C.A.T. Van den; Raaijmakers, Alexander J. E.

doi:10.1038/s41598-022-08004-7

Cited by 4 publications

(3 citation statements)

References 35 publications

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“…This was corrected by resampling in postprocessing (Section 2.4). Simulations were done using a 3T birdcage coil with ports at 45º, similar to the clinical coil, with the same geometry as previous studies 30 . A rectangular area centered around the coil isocenter was defined as the export region for all fields.…”

Section: Methodsmentioning

confidence: 99%

“…Simulations were done using a 3T birdcage coil with ports at 45 , similar to the clinical coil, with the same geometry as previous studies. 30 A rectangular area centered around the coil isocenter was defined as the export region for all fields. This region encompassed the brain and had dimensions of 260 mm in the x and y direction and 164 mm in the z direction.…”

Section: Simulationsmentioning

confidence: 99%

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A database for MR‐based electrical properties tomography with in silico brain data—ADEPT

Meerbothe,

Meliado,

Stijnman

et al. 2023

Magnetic Resonance in Med

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PurposeSeveral reconstruction methods for MR‐based electrical properties tomography (EPT) have been developed. However, the lack of common data makes it difficult to objectively compare their performances. This is, however, a necessary precursor for standardizing and introducing this technique in the clinical setting. To enable objective comparison of the performances of reconstruction methods and provide common data for their training and testing, we created ADEPT, a database of simulated data for brain MR‐EPT reconstructions.MethodsADEPT is a database containing in silico data for brain EPT reconstructions. This database was created from 25 different brain models, with and without tumors. Rigid geometric augmentations were applied, and different electrical properties were assigned to white matter, gray matter, CSF, and tumors to generate 120 different brain models. These models were used as input for finite‐difference time‐domain simulations in Sim4Life, used to compute the electromagnetic fields needed for MR‐EPT reconstructions.ResultsElectromagnetic fields from 84 healthy and 36 tumor brain models were simulated. The simulated fields relevant for MR‐EPT reconstructions (transmit and receive RF fields and transceive phase) and their ground‐truth electrical properties are made publicly available through ADEPT. Additionally, nonattainable fields such as the total magnetic field and the electric field are available upon request.ConclusionADEPT will serve as reference database for objective comparisons of reconstruction methods and will be a first step toward standardization of MR‐EPT reconstructions. Furthermore, it provides a large amount of data that can be exploited to train data‐driven methods. It can be accessed from https://doi.org/10.34894/V0HBJ8.

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Section: Methodsmentioning

confidence: 99%

Section: Simulationsmentioning

confidence: 99%

A database for MR‐based electrical properties tomography with in silico brain data—ADEPT

Meerbothe,

Meliado,

Stijnman

et al. 2023

Magnetic Resonance in Med

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show abstract

“…Other pioneering approaches include modification of RF transmission fields using RF arrays and parallel transmission with maximum-and null-current modes [29]. Machine-learning-based prediction of RF power absorption or ultrafast calculation of RF field enhancements near medical implants provide computational solutions for implant-specific RF heating assessment and management [30,31].…”

Section: Introductionmentioning

confidence: 99%

MRI of Implantation Sites Using Parallel Transmission of an Optimized Radiofrequency Excitation Vector

Berangi

Kuehne²,

Waiczies³

et al. 2023

Tomography

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Postoperative care of orthopedic implants is aided by imaging to assess the healing process and the implant status. MRI of implantation sites might be compromised by radiofrequency (RF) heating and RF transmission field (B1+) inhomogeneities induced by electrically conducting implants. This study examines the applicability of safe and B1+-distortion-free MRI of implantation sites using optimized parallel RF field transmission (pTx) based on a multi-objective genetic algorithm (GA). Electromagnetic field simulations were performed for eight eight-channel RF array configurations (f = 297.2 MHz), and the most efficient array was manufactured for phantom experiments at 7.0 T. Circular polarization (CP) and orthogonal projection (OP) algorithms were applied for benchmarking the GA-based shimming. B1+ mapping and MR thermometry and imaging were performed using phantoms mimicking muscle containing conductive implants. The local SAR10g of the entire phantom in GA was 12% and 43.8% less than the CP and OP, respectively. Experimental temperature mapping using the CP yielded ΔT = 2.5–3.0 K, whereas the GA induced no extra heating. GA-based shimming eliminated B1+ artefacts at implantation sites and enabled uniform gradient-echo MRI. To conclude, parallel RF transmission with GA-based excitation vectors provides a technical foundation en route to safe and B1+-distortion-free MRI of implantation sites.

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Simplified modeling of implanted medical devices with metallic filamentary closed loops exposed to low or medium frequency magnetic fields

Bottauscio¹,

Arduino²,

Chiampi³

et al. 2023

Computer Methods and Programs in Biomedicine

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A perturbation approach for ultrafast calculation of RF field enhancements near medical implants in MRI

Cited by 4 publications

References 35 publications

A database for MR‐based electrical properties tomography with in silico brain data—ADEPT

A database for MR‐based electrical properties tomography with in silico brain data—ADEPT

MRI of Implantation Sites Using Parallel Transmission of an Optimized Radiofrequency Excitation Vector

Simplified modeling of implanted medical devices with metallic filamentary closed loops exposed to low or medium frequency magnetic fields

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