Application of Gradient Reversal Fat Suppression technology (LIPO) in diffusion–weighted MR imaging of normal pancreas at 3.0T
Jin Shang1, Qi-yong Guo1, Bing Yu1, Yu Shi1, Kai-ning Shi2, and Ying Liu1

1Department of Radiology,Shengjing Hospital of China Medical University, Shenyang, China, People's Republic of, 2Imaging Systems Clinical Science,Philips Healthcare, Beijing, China, People's Republic of

Synopsis

At present, traditional fat suppression still brings heavy chemical-shift artifacts in diffusion weighted imaging (DWI) in abdomen 3T magnetic resonance scan. The purpose of this paper is to study the effect of two different DWI sequences for fat suppression on normal pancreas. From the above research, it can be concluded that DWI with LIPO may serve as an more effective method on improving the image quality of pancreas at 3.0T MR.

Background

Imperfect fat suppression, which is common in abdomen 3T magnetic resonance (MR) scan, causes heavy chemical-shift artifacts in diffusion weighted imaging (DWI) and affects lesions detection and clinical diagnosis. Gradient Reversal Fat suppression (LIPO) technique can provide improved fat suppression in a large FOV by reversing the slice selection gradient of the refocusing RF pulse. However, no research has been reported on the performance of this technique in normal pancreas.

Objective

To evaluate the clinical value of Gradient Reversal Fat Suppression technology (LIPO) in diffusion-weighted MR imaging of pancreas in normal volunteers on 3.0T MR scanner.

Methods

DWI-LIPO and conventional DWI sequence (b values 800 s/mm2) were performed among twenty healthy volunteers on a 3.0T whole-body MRI system (Ingenia, Philips Healthcare, The Netherlands). Apparent diffusion coefficient (ADC) values were calculated. ROIs were drawn on the head, body and tail of pancreas, The ADC value and image quality parameters including signal to noise ratio (SNR), blurring and artifacts level were evaluated by two experienced radiologists and the final result was reached after discussion when disagreement occurred. One–way ANOVA analysis and LSD test were used to compare DWI-LIPO sequence with conventional DWI whether statistically significant differences exist through the software SPSS 19.0.

Results

ADC value of pancreas showed no statistical difference between two different DWI sequences(P=0.172). Normal pancreas in DWI with LIPO has more higher SNR than conventional DWI(P=0.014); There was statistically difference between the SNR of pancreatic head or tails in DWI with LIPO and without LIPO(Table.1). Compared with conventional DWI sequence, the artifacts and image blurring degree scores both showed statistically difference in DWI with LIPO(P= 0.001、0.027)(Table.2).

Conclusion and discussion

Ideal fat suppression is hard to achieve with the conventional frequency-selective fat suppression method alone due to the inhomogeneity of B0 and B1 field in body imaging. The inversion of slice selective gradient, used in LIPO, can avoid the refocus of fat signal with chemical shift. The higher SNR of normal pancreas in LIPO may be caused by the refocus of signal from imperfect slice profile. In this study, normal pancreas in DWI with LIPO has lower artifact scores with uniform signals and clear edge than DWI with conventional fat sat. Therefore, DWI with LIPO may have the potential on improving the image quality of pancreas at 3.0T MR.

Acknowledgements

No acknowledgement found.

References

[1] Zoltan Nagy, Nikolaus Weiskopf. Efficient Fat Suppression by Slice-Selection Gradient Reversal in Twice-Refocused Diffusion Encoding. Magnetic Resonance in Medicine. 2008,60:1256–1260.

[2] Dow-Mu Koh&M, Blackledge&S, Burns&J, etal. Combination of chemical suppression techniques for dual suppression of fat and silicone at diffusion-weighted MR imaging in women with breast implants. Eur Radiol (2012) 22:2648–2653.

Figures

LIPO sequence diagram

The specific data of this paper is shown in Table1 and Table2

A twenty-three years old female with normal pancreas; pancreas tail in DWI with LIPO were homogeneous signal and edge sharpness(1a),while it were heterogeneous signal and blurring outline with follicular artifacts in conventional DWI(1b).

A twenty-three years old female with normal pancreas; The SNR of pancreas body in DWI with LIPO was 16.15(2a), while it was 12.38 in conventional DWI(2b).ROI=112.6mm2(white circle)



Proc. Intl. Soc. Mag. Reson. Med. 24 (2016)
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