T2-weighted MR imaging of the liver: qualitative and quantitative comparison of SPACE MR imaging with turbo spin-echo MR imaging

Abstract

Objective: To qualitatively and quantitatively compare T2-weighted MR imaging of the liver using volumetric spin-echo with sampling perfection with application-optimized contrast using different flip angle evolutions (SPACE) with conventional turbo spin-echo (TSE) sequence for fat-suppressed T2-weighted MR imaging of the liver.

Materials and methods: Thirty-three patients with suspected focal liver lesions had SPACE MR imaging and conventional fat-suppressed TSE MR imaging. Images were analyzed quantitatively by measuring the lesion-to-liver contrast-to-noise ratio (CNR), and the signal-to-noise ratio (SNR) of main focal hepatic lesions, hepatic and splenic parenchyma and qualitatively by evaluating the presence of vascular, respiratory motion and cardiac artifacts. Wilcoxon signed rank test was used to search for differences between the two sequences.

Results: SPACE MR imaging showed significantly greater CNR for focal liver lesions (median=22.82) than TSE MR imaging (median=14.15) (P<.001). No differences were found for SNR of hepatic parenchyma (P=.097), main focal hepatic lesions (P=.35), and splenic parenchyma (P=.25). SPACE sequence showed less artifacts than TSE sequence (vascular, P<.001; respiratory motion, P<.001; cardiac, P<.001) but needed a longer acquisition time (228.4 vs. 162.1s; P<.001).

Conclusion: SPACE MR imaging provides a significantly increased CNR for focal liver lesions and less artifacts by comparison with the conventional TSE sequence. These results should stimulate further clinical studies with a surgical standard of reference to compare the two techniques in terms of sensitivity for malignant lesions.

Keywords: Extended echo trains; Liver imaging; MR imaging technique; SPACE.