Investigating cardiac stimulation limits of MRI gradient coils using electromagnetic and electrophysiological simulations in human and canine body models

Klein, Valerie; Davids, Mathias; Schad, Lothar R.; Wald, Lawrence L.; Guérin, Bastien

doi:10.1002/mrm.28472

Cited by 14 publications

(26 citation statements)

References 67 publications

(183 reference statements)

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“…It is also worth noting that PNS effects are of concern when switching times are in 0.1ms to ≈1ms range and are negligible when switching time is >5ms, given | |<100mT [28]. Considering the rise-time along with the peak | |⁄ value, the International Electrotechnical Commission (IEC) thresholds for PNS and Cardiac Stimulations have a common asymptotic value of 20T/s at long rise-times (>5ms), thus implying complete safety of the gradient-switching employed in this work [29].…”

Section: Measurement Resultsmentioning

confidence: 89%

Wireless 3D Surgical Navigation and Tracking System With 100μm Accuracy Using Magnetic-Field Gradient-Based Localization

Sharma

Telikicherla

Ding

et al. 2021

IEEE Trans. Med. Imaging

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This paper describes a high-resolution 3D navigation and tracking system using magnetic field gradients, that can replace X-Ray fluoroscopy in highprecision surgeries. Monotonically varying magnetic fields in X, Y and Z directions are created in the field-of-view (FOV) to produce magnetic field gradients, which encode each spatial point uniquely. Highly miniaturized, wireless and battery-less devices, capable of measuring their local magnetic field, are designed to sense the gradient field. One such device can be attached to an implant inside the body and another to a surgical tool, such that both can simultaneously measure and communicate the magnetic field at their respective locations to an external receiver. The relative location of the two devices on a real-time display can enable precise surgical navigation without using X-Rays. A prototype device is designed consisting of a micro-chip fabricated in 65nm CMOS technology, a 3D magnetic sensor and an inductor-coil. Planar electromagnetic coils are designed for creating the 3D magnetic field gradients in a 20x20x10cm 3 of scalable FOV. Unambiguous and orientation-independent spatial encoding is achieved by: (i) using the gradient in the total field magnitude instead of only the Z-component; and (ii) using a combination of the gradient fields to correct for the nonlinearity and non-monotonicity in X and Y gradients. The resultant X and Y FOV yield ≥90% utilization of their respective coil-span. The system is tested in vitro to demonstrate a localization accuracy of <100µm in 3D, the highest reported to the best of our knowledge.

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Section: Measurement Resultsmentioning

confidence: 89%

Wireless 3D Surgical Navigation and Tracking System With 100μm Accuracy Using Magnetic-Field Gradient-Based Localization

Sharma

Telikicherla

Ding

et al. 2021

IEEE Trans. Med. Imaging

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“…40 V/m) [8]. We have recently extended our PNS modeling tool towards electromagnetically induced cardiac stimulation to study this concern in more detail [60].…”

Section: Discussionmentioning

confidence: 99%

Optimization of MRI Gradient Coils With Explicit Peripheral Nerve Stimulation Constraints

Davids¹,

Guérin²,

Klein³

et al. 2021

IEEE Trans. Med. Imaging

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Peripheral Nerve Stimulation (PNS) limits the acquisition rate of Magnetic Resonance Imaging data for fast sequences employing powerful gradient systems. The PNS characteristics are currently assessed after the coil design phase in experimental stimulation studies using constructed coil prototypes. This makes it difficult to find design modifications that can reduce PNS. Here, we demonstrate a direct approach for incorporation of PNS effects into the coil optimization process. Knowledge about the interactions between the applied magnetic fields and peripheral nerves allows the optimizer to identify coil solutions that minimize PNS while satisfying the traditional engineering constraints. We compare the simulated thresholds of PNS-optimized body and head gradients to conventional designs, and find an up to 2-fold reduction in PNS propensity with moderate penalties in coil inductance and field linearity, potentially doubling the image encoding performance that can be safely used in humans. The same framework may be useful in designing and operating magneto-and electro-stimulation devices.

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“…Amplitude and rapid switching of gradient coils during image acquisition may cause peripheral nerve stimulation. 47 However, as millions of MRIs are performed globally each year, 48 fatalities are extremely rare. 49 …”

Section: Magnetic Resonance Imagingmentioning

confidence: 99%

Application of Advanced Imaging Modalities in Veterinary Medicine: A Review

Yitbarek¹,

Dagnaw²

2022

VMRR

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Veterinary anatomy has traditionally relied on detailed dissections to produce anatomical illustrations, but modern imaging modalities, now represent an enormous resource that allows for fast non-invasive visualizations in living animals for clinical and research purposes. In this review, advanced anatomical imaging modalities and their applications, safety issues, challenges, and future prospects of the techniques commonly employed for animal imaging would be highlighted. The quality of diagnostic imaging equipment in veterinary practice has greatly improved. Recent advances made in veterinary advanced imaging specifically about cross-sectional modalities (CT and MRI), nuclear medicine (PET, SPECT), and dual imaging modalities (PET/CT, PET/MR, and SPECT/CT) have become widely available, leading to greater demands and expectations from veterinary clients. These modalities allow for the creation of three-dimensional representations that can be of considerable value in the dissemination of clinical diagnosis and anatomical studies. Despite, the modern imaging modalities well established in developed countries across the globe, it is yet to remain in its infancy stage in veterinary practice in developing countries due to heavy initial investment and maintenance costs, lack of expert interpretation, a requirement of specialized technical staff and need of adjustable machines to accommodate the different range of animal sizes. Therefore, veterinarians should take advantage of these imaging techniques in designing future experiments by considering the availability of these varied imaging modalities and the creation of three-dimensional graphical representations of internal structures.

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Investigating cardiac stimulation limits of MRI gradient coils using electromagnetic and electrophysiological simulations in human and canine body models

Cited by 14 publications

References 67 publications

Wireless 3D Surgical Navigation and Tracking System With 100μm Accuracy Using Magnetic-Field Gradient-Based Localization

Wireless 3D Surgical Navigation and Tracking System With 100μm Accuracy Using Magnetic-Field Gradient-Based Localization

Optimization of MRI Gradient Coils With Explicit Peripheral Nerve Stimulation Constraints

Application of Advanced Imaging Modalities in Veterinary Medicine: A Review

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