Highly accelerated acquisition and homogeneous image reconstruction with rotating RF coil array at 7T—A phantom based study

Li, Mingyan; Zuo, Zhentao; Jin, Jin; Xue, Rong; Trakic, Adnan; Weber, Ewald; F, Liu; Crozier, Stuart

doi:10.1016/j.jmr.2013.11.002

Cited by 9 publications

(36 citation statements)

References 34 publications

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“…As described in previous work [14], the RRFCA moves to various angular positions during acquisition, so that different k-space phase-encoding lines are associated with distinct coil sensitivity profiles which improve encoding capability. In order to reduce the overall scan time, sensitivity maps at most angular positions are estimated from a small number of measured in vivo sensitivity maps, by employing the proposed algorithm.…”

Section: Methodsmentioning

confidence: 99%

“…As an alternative method, we have introduced the rotating radiofrequency coil (RRFC) [10,11] and the rotating radiofrequency coil array (RRFCA) [12][13][14] to reduce scan duration by using SENSE-like reconstruction methods. Both rotating RF systems are capable of encoding k-space data with varying sensitivity profiles ( 1 B  ), which benefit the signal encoding process and reconstruction algorithms.…”

Section: Introductionmentioning

confidence: 99%

“…The RRFCA used a rotating-SENSE algorithm that featured time-varying sensitivity profiles for image reconstruction. A 4-element RRFCA was prototyped and tested with a homogeneous phantom at 7 Tesla, which exhibited improved g-maps [7] and uniform signal-to-noise ratio (SNR) distributions compared with a traditional 8-element coil array [12,14].…”

Section: Introductionmentioning

confidence: 99%

“…Since the rotating-SENSE algorithm needs sensitivity information for image reconstruction, in our previous studies [11,14], a small number of sensitivity maps acquired at several angular positions was numerically rotated to estimate sensitivity at other positions. This technique was used for human brain imaging at 2 Tesla [10,11] owing to the negligible coil-tissue interaction [15][16][17][18][19] (dielectric resonance [20][21][22][23][24]).…”

Section: Introductionmentioning

confidence: 99%

“…This approach has been also used for imaging a homogeneous phantom at 7 Tesla, provided the phantom and the RRFCA system are both symmetrical [14]. However, this method is not applicable for in vivo sensitivity estimation at 7 Tesla, because the in vivo sensitivity maps at different angular positions vary significantly.…”

Section: Introductionmentioning

confidence: 99%

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In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Jin

Zuo

et al. 2015

Journal of Magnetic Resonance

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Using a new rotating SENSitivity Encoding (rotating-SENSE) algorithm, we have successfully demonstrated that the rotating radiofrequency coil array (RRFCA) is capable of achieving a significant reduction in scan time and a uniform image reconstruction for a homogeneous phantom at 7 Tesla. However, at 7 Tesla the in vivo with the same number of coil elements, the RRFCA was able to reconstruct good quality images at a high reduction factor. It is hoped that the proposed sensitivity estimation algorithm and the acceleration ability of the RRFCA will be particularly useful for ultra high field MRI.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Jin

Zuo

et al. 2015

Journal of Magnetic Resonance

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Accelerated MRI at 9.4 T with electronically modulated time‐varying receive sensitivities

Glang

Nikulin

Bause

et al. 2022

Magnetic Resonance in Med

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Purpose To investigate how electronically modulated time‐varying receive sensitivities can improve parallel imaging reconstruction at ultra‐high field. Methods Receive sensitivity modulation was achieved by introducing PIN diodes in the receive loops, which allow rapid switching of capacitances in both arms of each loop coil and by that alter B1− profiles, resulting in two distinct receive sensitivity configurations. A prototype 8‐channel reconfigurable receive coil for human head imaging at 9.4T was built, and MR measurements were performed in both phantom and human subject. A modified SENSE reconstruction for time‐varying sensitivities was formulated, and g‐factor calculations were performed to investigate how modulation of receive sensitivity profiles during image encoding can improve parallel imaging reconstruction. The optimized modulation pattern was realized experimentally, and reconstructions with the time‐varying sensitivities were compared with conventional static SENSE reconstructions. Results The g‐factor calculations showed that fast modulation of receive sensitivities in the order of the ADC dwell time during k‐space acquisition can improve parallel imaging performance, as this effectively makes spatial information of both configurations simultaneously available for image encoding. This was confirmed by in vivo measurements, for which lower reconstruction errors (SSIM = 0.81 for acceleration R = 4) and g‐factors (max g = 2.4; R = 4) were observed for the case of rapidly switched sensitivities compared to conventional reconstruction with static sensitivities (SSIM = 0.74 and max g = 3.2; R = 4). As the method relies on the short RF wavelength at ultra‐high field, it does not yield significant benefits at 3T and below. Conclusions Time‐varying receive sensitivities can be achieved by inserting PIN diodes in the receive loop coils, which allow modulation of B1− patterns. This offers an additional degree of freedom for image encoding, with the potential for improved parallel imaging performance at ultra‐high field.

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Accelerated 2D Cartesian MRI with an 8‐channel local B₀ coil array combined with parallel imaging

Tian,

Uecker,

Davids

et al. 2023

Magnetic Resonance in Med

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PurposeIn MRI, the magnetization of nuclear spins is spatially encoded with linear gradients and radiofrequency receivers sensitivity profiles to produce images, which inherently leads to a long scan time. Cartesian MRI, as widely adopted for clinical scans, can be accelerated with parallel imaging and rapid magnetic field modulation during signal readout. Here, by using an 8‐channel local coil array, the modulation scheme optimized for sampling efficiency is investigated to speed up 2D Cartesian scans.Theory and MethodsAn 8‐channel local coil array is made to carry sinusoidal currents during signal readout to accelerate 2D Cartesian scans. An MRI sampling theory based on reproducing kernel Hilbert space is exploited to visualize the efficiency of nonlinear encoding in arbitrary sampling duration. A field calibration method using current monitors for local coils and the ESPIRiT algorithm is proposed to facilitate image reconstruction. Image acceleration with various modulation field shapes, aliasing control, and distinct modulation frequencies are scrutinized to find an optimized modulation scheme. A safety evaluation is conducted. In vivo 2D Cartesian scans are accelerated by the local coils.ResultsFor 2D Cartesian MRI, the optimal modulation field by this local array converges to a nearly linear gradient field. With the field calibration technique, it accelerates the in vivo scans (i.e., proved safe) by threefold and eightfold free of visible artifacts, without and with SENSE, respectively.ConclusionThe nonlinear encoding analysis tool, the field calibration method, the safety evaluation procedures, and the in vivo reconstructed scans make significant steps to push MRI speed further with the local coil array.

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Highly accelerated acquisition and homogeneous image reconstruction with rotating RF coil array at 7T—A phantom based study

Cited by 9 publications

References 34 publications

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Accelerated MRI at 9.4 T with electronically modulated time‐varying receive sensitivities

Accelerated 2D Cartesian MRI with an 8‐channel local B₀ coil array combined with parallel imaging

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Highly accelerated acquisition and homogeneous image reconstruction with rotating RF coil array at 7T—A phantom based study

Cited by 9 publications

References 34 publications

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

In vivo sensitivity estimation and imaging acceleration with rotating RF coil arrays at 7 Tesla

Accelerated MRI at 9.4 T with electronically modulated time‐varying receive sensitivities

Accelerated 2D Cartesian MRI with an 8‐channel local B0 coil array combined with parallel imaging

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Accelerated 2D Cartesian MRI with an 8‐channel local B₀ coil array combined with parallel imaging