TY  - GEN
A1  - Frauenrath, Tobias
A1  - Pfeiffer, Harald
A1  - Hezel, Fabian
A1  - Dieringer, Matthias A.
A1  - Winter, Lukas
A1  - Gräßl, Andreas
A1  - Santoro, Davide
A1  - Özerdem, Celal
A1  - Renz, Wolfgang
A1  - Greiser, Andreas
A1  - Niendorf, Thoralf
T1  - Lessons learned from cardiac MRI at 7.0 T: LV function assessment at 3.0 T using local multi-channel transceiver coil arrays
T2  - 2012 ISMRM Annual Meeting Proceedings
N2  - Cardiac MR (CMR) is of proven clinical value but also an area of vigorous ongoing research since image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Recent developments of CMR at 7.0 T have been driven by pioneering explorations into novel multichannel transmit and receive coil array technology to tackle the challenges B1+-field inhomogeneities, to offset specific-absorption rate (SAR) constraints and to reduce banding artifacts in SSFP imaging. For this study, recognition of the benefits and performance of local surface Tx/Rx-array structures recently established at 7.0 T inspired migration to 3.0 T, where RF inhomogeneities and SAR limitations encountered in routine clinical CMR, though somewhat reduced versus the 7.0 T situation, remain significant. For all these reasons, this study was designed to build and examine the feasibility of a local four channel Tx/Rx cardiac coil array for anatomical and functional cardiac imaging at 3.0 T. For comparison, a homebuilt 4 channel Rx cardiac coil array exhibiting the same geometry as the Tx/Rx coil and a Rx surface coil array were used.
Y1  - 2012
SN  - 1545-4428
N1  - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia
ER  - 
TY  - GEN
A1  - Gräßl, Andreas
A1  - Renz, Wolfgang
A1  - Hezel, Fabian
A1  - Frauenrath, Tobias
A1  - Pfeiffer, Harald
A1  - Hoffmann, Werner
A1  - Kellmann, Peter
A1  - Martin, Conrad
A1  - Niendorf, Thoralf
T1  - Design, evaluation and application of a modular 32 channel transmit/receive surface coil array for cardiac MRI at 7T
T2  - 2012 ISMRM Annual Meeting Proceedings
N2  - Cardiac MR (CMR) at ultrahigh (≥7.0 T) fields is regarded as one of the most challenging MRI applications. At 7.0 T image quality is not always exclusively defined by signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR). Detrimental effects bear the potential to spoil the signal-to-noise (SNR) and contrast-to-noise (CNR) benefits of cardiac MR (CMR) at 7.0 T. B₁⁺-inhomogeneities and signal voids represent the main challenges. Various pioneering coil concepts have been proposed to tackle these issues, enabling cardiac MRI at 7.0 T. This includes a trend towards an ever larger number of transmit and receive channels.  This approach affords multi-dimensional B₁⁺ modulations to improve B₁⁺ shimming performance and to enhance RF efficiency. Also, parallel imaging benefits from a high number of receive channels enabling two-dimensional acceleration. Realizing the limitations of existing coil designs tailored for UHF CMR and recognizing the opportunities of a many element TX/RX channel architecture this work proposes a modular, two dimensional 32-channel transmit and receive array using loop elements and examines its efficacy for enhanced B¹+ homogeneity and improved parallel imaging performance.
Y1  - 2012
SN  - 1545-4428
N1  - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia
ER  - 
TY  - JOUR
A1  - Gräßl, Andreas
A1  - Renz, Wolfgang
A1  - Hezel, Fabian
A1  - Dieringer, Matthias A.
A1  - Winter, Lukas
A1  - Özerdem, Celal
A1  - Rieger, Jan
A1  - Kellmann, Peter
A1  - Santoro, Davide
A1  - Lindel, Tomasz D.
A1  - Frauenrath, Tobias
A1  - Pfeiffer, Harald
A1  - Niendorf, Thoralf
T1  - Modular 32-channel transceiver coil array for cardiac MRI at 7.0T
JF  - Magnetic Resonance in Medicine
N2  - Purpose
To design and evaluate a modular transceiver coil array with 32 independent channels for cardiac MRI at 7.0T.

Methods
The modular coil array comprises eight independent building blocks, each containing four transceiver loop elements. Numerical simulations were used for B1+ field homogenization and radiofrequency (RF) safety validation. RF characteristics were examined in a phantom study. The array's suitability for accelerated high spatial resolution two-dimensional (2D) FLASH CINE imaging of the heart was examined in a volunteer study.

Results
Transmission field adjustments and RF characteristics were found to be suitable for the volunteer study. The signal-to-noise intrinsic to 7.0T together with the coil performance afforded a spatial resolution of 1.1 × 1.1 × 2.5 mm3 for 2D CINE FLASH MRI, which is by a factor of 6 superior to standardized CINE protocols used in clinical practice at 1.5T. The 32-channel transceiver array supports one-dimensional acceleration factors of up to R = 4 without impairing image quality significantly.

Conclusion
The modular 32-channel transceiver cardiac array supports accelerated and high spatial resolution cardiac MRI. The array is compatible with multichannel transmission and provides a technological basis for future clinical assessment of parallel transmission techniques at 7.0T.
Y1  - 2013
U6  - https://doi.org/10.1002/mrm.24903
SN  - 1522-2594
VL  - 72
IS  - 1
SP  - 276
EP  - 290
PB  - Wiley-Liss
CY  - New York
ER  -