Volume 72, Issue 1 pp. 220-226

Note

7 Tesla MRI with a transmit/receive loopless antenna and B₁-insensitive selective excitation

M. Arcan Erturk,

M. Arcan Erturk

Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

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AbdEl-Monem M. El-Sharkawy,

AbdEl-Monem M. El-Sharkawy

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

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Jay Moore,

Jay Moore

Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA

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Paul A. Bottomley,

Corresponding Author

Paul A. Bottomley

Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

Correspondence: Paul A. Bottomley, Ph.D., Division of MR Research, Department of Radiology, Johns Hopkins University, 601 N. Caroline Street, Baltimore, MD 21287. E-mail: [email protected]Search for more papers by this author

M. Arcan Erturk,

M. Arcan Erturk

Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

Search for more papers by this author

AbdEl-Monem M. El-Sharkawy,

AbdEl-Monem M. El-Sharkawy

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

Search for more papers by this author

Jay Moore,

Jay Moore

Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, Tennessee, USA

Search for more papers by this author

Paul A. Bottomley,

Corresponding Author

Paul A. Bottomley

Department of Electrical and Computer Engineering, Johns Hopkins University, Baltimore, Maryland, USA

Russell H. Morgan Department of Radiology and Radiological Sciences, Johns Hopkins University, Baltimore, Maryland, USA

First published: 20 August 2013

https://doi.org/10.1002/mrm.24910

Citations: 6

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Abstract

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 and field-of-view with field-strength previously reported for internal loopless antennae at 7T can suffice to perform MRI with an interventional transmit/receive antenna without using any external coils.

Methods

External coils were replaced by semi-rigid or biocompatible transmit/receive loopless antennae requiring only a few Watts of peak RF power. Slice selection was provided by spatially selective B₁-insensitive composite RF pulses that compensate for the antenna's intrinsically nonuniform B₁-field. Power was adjusted to maintain local temperature rise ≤1°C. Fruit, intravascular MRI of diseased human vessels in vitro, and MRI of rabbit aorta in vivo are demonstrated.

Results

Scout MRI with the transmit/receive antennae yielded a ≤10 cm cylindrical field-of-view, enabling subsequent targeted localization at ∼100 μm resolution in 10-50 s and/or 50 μm MRI in ∼2 min in vitro, and 100−300 μm MRI of the rabbit aorta in vivo.

Conclusion

A simple, low-power, one-device approach to interventional MRI at 7T offers the potential of truly high-resolution MRI, while avoiding issues with external coil excitation and interactions at 7T. Magn Reson Med 72:220–226, 2014. © 2013 Wiley Periodicals, Inc.

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Volume72, Issue1

July 2014

Pages 220-226

7 Tesla MRI with a transmit/receive loopless antenna and B₁-insensitive selective excitation

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Purpose

Methods

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Conclusion

REFERENCES

Citing Literature

References

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7 Tesla MRI with a transmit/receive loopless antenna and B1-insensitive selective excitation

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7 Tesla MRI with a transmit/receive loopless antenna and B₁-insensitive selective excitation