Jul 25, 2020 · An important tool for this purpose is B0 simulation of multi-coil shim performance based on in vivo field maps. Using simulations, we are now exploring "hybrid" approaches in which integrated RF-shim loops are combined with strategically-placed shim-only loops to improve shim performance.

We introduce fast B1 calibration tools utilizing some linear algebra formalism with transmit coil arrays, ranging from simple (relative B1 phase) to more demanding measures (absolute B1 magnitude). We show that local B1 Phase Shim can be performed in less than one minute with a 16 elements transmit coil array, with dramatic gain.

Aug 14, 2024 · The integration of RF and shim coils brings a high shim efficiency due to the proximity of participants. This technique will potentially be applied to high-density RF coils with a high-density shim array for improved B 0 homogeneity.

Sep 6, 2006 · RF shimming should be more effective at lower frequencies, with more elements, or over a smaller ROI. Here we investigate some of the limitations of RF shimming by going to very high frequencies (600 MHz) and using a large number of elements.

CONCLUSION: Integrated RF/shim arrays provide a more efficient alternative to spherical harmonic shimming and independent MC shim arrays. Applications to be explored include global shimming, slice-optimized shimming, and dynamic shimming to compensate for …

RF shimming is a simplified form of pTx, where the complex weights of different transmit channels are optimized to improve image quality.

Oct 17, 2023 · Purpose: To develop a flexible, lightweight, and multi-purpose integrated parallel reception, excitation, and shimming (iPRES) coil array that can conform to the subject's anatomy and perform MR imaging and localized B 0 shimming in different anatomical regions with a high SNR, shimming performance, ease of positioning, and subject comfort.

Mar 23, 2018 · RF Shim Prediction by Iteratively Projected Ridge Regression (PIPRR) predicts patient-specific, SAR-efficient RF shims with a machine learning approach that merges learning with training shim design. To evaluate it, a set of maps was simulated for 100 human heads for a 24-element coil at 7T.

To achieve comparable power requirements for all transmit (TX) channels, this study investigates “double-regularized” RF shimming, minimizing the mean as well as the maximum RF power. The approach was tested in abdominal applications for a whole-body, 8-channel TX/RX system operating at 3T [3,4].

The purpose of this work was to develop a novel integrated radiofrequency and shim (RF/shim) coil array that can perform parallel reception and localized B0 shimming in the human brain with the same coils, thereby maximizing both the signal-to-noise ratio and shimming efficiency.