Purpose To develop a 16‐channel transceive body imaging array at 7.0 T with improved transmit, receive, and specific absorption rate (SAR) performance by combining both loop dipole elements using their respective complementary near far field characteristics. Methods A radiofrequency (RF) coil consisting of eight loop‐dipole blocks (16LD) was designed constructed. Transmit receive quantitatively investigated in phantom human model simulations, experiments on five healthy volunteers inside the...

Purpose To explore the potential of performing body imaging at 10.5 Tesla (T) compared with 7.0T through evaluating transmit/receive performance similarly configured dipole antenna arrays. Methods Fractionated elements for 10.5T were designed and evaluated using numerical simulations. Transmit arrays inside prostate, kidneys heart investigated those both phase‐only radiofrequency (RF) shimming multi‐spoke pulses. Signal‐to‐noise ratio (SNR) comparisons also performed. A 10‐channel array was...

Purpose To investigate the feasibility of imaging human torso and to evaluate performance several radiofrequency (RF) management strategies at 10.5T. Methods Healthy volunteers were imaged on a 10.5T whole‐body scanner in multiple target anatomies, including prostate, hip, kidney, liver, heart. Phase‐only shimming spoke pulses used demonstrate their managing inhomogeneity present 447 MHz. Imaging protocols included both qualitative quantitative acquisitions show with different contrasts....

Purpose To improve imaging performance for body MRI with a local transmit array at 10.5T, the geometry of dipole antenna was optimized to achieve lower peak specific absorption rate (SAR) levels and more uniform profile. Methods Electromagnetic simulations on phantom were used evaluate SAR ‐performance different geometries. The best performing (the snake antenna) simulated human models in 12‐channel configuration safety assessment comparison previous design. This constructed after which...

Abstract Purpose To increase the RF coil performance and management for body imaging at 10.5 T by validating evaluating a high‐density 16‐channel transceiver array, implementing virtual observation points (VOPs), demonstrating specific absorption rate (SAR) constrained in vivo. Methods The inaccuracy of electromagnetic model array was quantified based on B 1 + SAR data. Inter‐subject variability estimated using new approach relative deviation different shims between human models. pTx...

Improving the signal-to-noise-ratio (SNR) of magnetic resonance imaging (MRI) using denoising techniques could enhance their value, provided that signal statistics and image resolution are not compromised. Here, a new method based on spectral subtraction measured noise power from each acquisition is presented. Spectral (SSD) assumes no prior knowledge acquired does increase time. Whereas conventional denoising/filtering methods compromised in parallel by spatially dependent statistics, SSD...

Purpose This study investigates the implications of all degrees freedom within‐scan patient head motion on safety. Methods Electromagnetic simulations were performed by displacing and/or rotating a virtual body model inside an 8‐channel transmit array to simulate 6 motion. Rotations up 20° and displacements 20 mm including off‐axis axial/coronal translations investigated, yielding 104 positions. Quadrature excitation, RF shimming, multi‐spoke parallel‐transmit excitation pulses designed for...

Purpose To develop and evaluate a sterilizable multichannel endorectal coil (ERC) for use in combination with an external surface array (ESA) high‐resolution anatomical functional studies of the prostate at 7T. Materials Methods A two‐loop ERC (ERC‐2L) microstrip‐loop (ERC‐ML) were compared 7T terms transmit receive performance. The best‐performing was evaluated alone ESA through 1) simulations on both phantom anatomically correct numerical human model to assess specific absorption rate...

Abstract The loopless antenna magnetic resonance imaging detector is comprised of a tuned coaxial cable with an extended central conductor that can be fabricated at submillimeter diameters for interventional use in guidewires, catheters, or needles. Prior work up to 4.7 T suggests near‐quadratic gain signal‐to‐noise ratio field strength and safe operation 3 T. Here, the first time, performance radiofrequency safety are investigated both theoretically, using electromagnetic method‐of‐moments,...

Purpose To develop and demonstrate in vitro vivo a single interventional magnetic resonance (MR)-active device that integrates the functions of precise identification tissue site with delivery radiofrequency (RF) energy for ablation, high-spatial-resolution thermal mapping to monitor dose, quantitative MR imaging relaxometry document ablation-induced changes characterizing ablated tissue. Materials Methods All animal studies were approved by institutional care use committee. A loopless...

<h3>Background</h3> Many epidural and peripheral nerve catheters contain conducting wire that could heat during magnetic resonance imaging (MRI), requiring removal for scanning. <h3>Methods</h3> We tested 2 each of 6 brands regional analgesia (from Arrow International [Reading, Pennsylvania], B. Braun Medical Inc [Bethlehem, Smiths Medical/Portex [Keene, New Hampshire]) exposure to clinical 1.5- 3-T MRI. Catheters testing as nonmagnetic were placed in an configuration a standard human...

Purpose To validate electromagnetic and thermal simulations with in vivo temperature measurements, to demonstrate a framework that can be used predict increase caused by radiofrequency (RF) excitation dipole transmitter arrays. Methods Dipole arrays were deliver RF energy the back/neck region of swine using different patterns (n = 2–4 per swine) for heating. The anesthetized 3) was measured fluoroscopic probes 12) compared against modeling from animal‐specific simulations. Results Simulated...

A loop+dipole transceiver antenna array was designed for 447 MHz /10.5 tesla human head imaging. This achieved by a geometrically decoupled combination of loop and dipole without inter-element decoupling circuitry. We made comparisons between an 8-channel only array, 16-channel combined through simulation using the finite difference time domain (FDTD) method MR imaging experiments.

Purpose Use of external coils with internal detectors or conductors is challenging at 7 Tesla (T) due to radiofrequency (RF) field (B1) penetration, B1-inhomogeneity, mutual coupling, and potential local RF heating. The present study tests whether the near-quadratic gains in signal-to-noise ratio field-of-view field-strength previously reported for loopless antennae 7T can suffice perform MRI an interventional transmit/receive antenna without using any coils. Methods External were replaced...

A sixteen-channel array consisting of eight pairs stacked loop and dipole antennas was simulated for head MRI applications at 10.5 Tesla. Remcom XFdtd used to calculate isolation between elements modeled with a dielectric load varying space elements. loop-dipole assembly candidate element configuration head-shaped phantom.

Purpose: Radiofrequency (RF) radiometry uses thermal noise detected by an antenna to measure the temperature of objects independent medical imaging technologies such as magnetic resonance (MRI). Here, active interventional MRI can be deployed a RF radiometer local heating, possible new method monitoring device safety and therapy. Methods: A 128 MHz receiver was fabricated voltage from 3 T loopless calibrated for in uniformly heated bioanalogous gel phantom. Local heating (Δ ) induced using...

MRI gradient-fields may induce extrinsic voltage between electrodes and conductive neurostimulator enclosure of implanted deep brain stimulation (DBS) systems, cause unintended and/or malfunction. Electromagnetic (EM) simulations using detailed anatomical human models, therapy implant trajectories, gradient coil models can be used to calculate clinically relevant induced levels. Incorporating additional into the EM simulation library help achieve more accurate levels, however, adding new...

To propose a single setup using the MRI to both measure and validate transfer function (TF) of linear implants. Conventionally, TF an implant is measured in one bench validated another.

De-noising techniques can improve the signal to noise ratio (SNR), and quality of magnetic resonance (MR) images. In this work, we introduce a spectral subtraction de-noising (SSD) method that operates directly on acquired raw MR signals then reconstruct images using de-noised SNR. coil arrays reconstructed parallel imaging exhibit spatially varying distribution, which hampers performance image applied in domain. The proposed SSD is k-space (Fourier) domain each individual array elements...

To realize the increased pTx functionality of a 16-channel transceiver dipole array for body imaging at 10.5T, validation process was implemented. After quantifying uncertainty RF arrays electromagnetic simulations total safety factor determined enabling implementation real-time local SAR monitoring on scanner through use virtual observation points (VOP). In vivo data acquired with VOP enabled power demonstrating shimming performance and without constrained optimizations.

Performing sodium and proton imaging in the same study can provide a wealth of unique multinuclear insights for pathologies their treatment. However, coils to perform such studies human body are limited none were validated use at 10.5T until now. While both nuclei benefit from increased SNR suffers low due lower gyromagnetic ratio natural abundance compared 1 H. First in-vivo results presented sodium-proton torso array following safety validation determining safe operating limits.

Background and Aims: Our aim was to compare the efficacy of superparamagnetic iron oxide magnetic resonance imaging conventional non-contrast methods in detection hepatic metastases. Materials Methods: In our study, we compared results obtained by without contrast cases with primary tumor diagnosis evaluating their metastatic lesions. Through application two above-mentioned methods, a total 13 patients who underwent examination means 1.5 tesla superconducting magnet, demonstrated visibility...