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Combination of IDEAL and ARC imaging to obtain homogeneous fat saturation in the brachial plexus within clinically acceptable time parameters 2008

General Spine

Allison Grayev, MD,
Scott Reeder, MD, PhD, Non ASSR Member
Victor Haughton, MD, ASSR Member
Lindell Gentry, MD, Non ASSR Member

Scientific Paper

Purpose

Comprehensive MR imaging of the brachial plexus has been severely limited by poor fat suppression. The IDEAL (Iterative Decomposition of water and fat with Echo Asymmetry and Least squares estimation)is a three-echo, chemical shift based approach that can provide homogeneous separation of water and fat despite B0 and B1 inhomogeneities [1]. Although IDEAL has been successfully applied to the brachial plexus [2], it suffers from a three-fold increase in scan time. The purpose of this study was to combine IDEAL imaging with Autocalibrating Reconstruction for Cartesian sampling (ARC) parallel imaging to reduce the minimum scan time while maintaining a high signal to noise ratio (SNR).

Methods & Materials

IDEAL-ARC images were reconstructed with an on-line reconstruction algorithm, which provides separate water, fat and recombined in-phase (water + fat) and out of phase (water - fat) images, following acquisition of T1 and T2 weighted images. The remainder of the examination was completed using traditional T1 and T2 FSE sequences without and with fat saturation.

Results

Uniform separation of water and fat was seen throughout the brachial plexus. Images had high SNR and excellent image quality was seen in all images.
Figure 1: Axial T1 FSE with fat saturation demonstrating areas of failed fat suppression as well as areas of water suppression.
Figure 2: Axial T1 FSE IDEAL-ARC demonstrating homogeneous fat suppression while maintaining high SNR.
Figure 3: Coronal T2 FSE with fat saturation demonstrating failed fat suppression.
Figure 4: Coronal T2 FSE IDEAL-ARC demonstrating homogeneous fat suppression and high SNR.

Conclusion

IDEAL imaging provides homogeneous fat saturation throughout the brachial plexus; however, until recently, the length of time needed to acquire the images limited clinical applicability. Combining ARC parallel imaging with IDEAL allows maintenance of high SNR performance within clinically acceptable scan durations.

References

References:
1. Reeder, et al. MRM 2005 54:636-644
2. Reeder, et al. JMRI 2006 24:825-832

Financial Disclosures:
Reeder - GE Healthcare

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