High Spatial Resolution, Respiratory-Gated, T1-Weighted Magnetic Resonance Imaging of the Liver and the Biliary Tract During the Hepatobiliary Phase of Gadoxetic Acid–Enhanced Magnetic Resonance Imaging

Abstract

The aim of this study was to demonstrate the clinical feasibility of a recently developed navigator-gated, 3-dimensional gradient echo (3D-GRE) sequence for high-resolution, T1-weighted imaging (HR-T1WI) during the hepatobiliary phase (HBP) of gadoxetic acid-enhanced liver magnetic resonance imaging (MRI). Eighty-seven consecutive patients who underwent gadoxetic acid-enhanced liver MRI were included in this study. To obtain HR-T1WI (acquired resolution, 1 × 1 × 2 mm), a gated 3D-GRE sequence (gated volumetric interpolated breath-hold examination [VIBE]; Siemens) with fat suppression was performed during the HBP and was then compared with standard breath-hold (BH)-GRE sequence (BH-VIBE). For the respiration gating, the phase ordering using the automatic window selection technique was used. Three readers independently scored the artifacts and the imaging quality (IQ) of both image sets and also classified BH-VIBE images into acceptable or unacceptable IQ. Noise and signal-noise ratio of the BH-VIBE and gated-VIBE sequences were compared, and image quality improvement using gated VIBE compared with BH-VIBE was determined when BH-VIBE shows unacceptable IQ. The gated-VIBE sequence successfully provided HR-T1WI, having diagnosable image quality in all patients except 4 patients in 1 reader (95.4%, 83/87). The gated-VIBE sequence showed relatively higher levels of noise (mean [SD], 6.04 [3.18] vs. 3.57 [0.66]) but similar signal-noise ratio (93.60 [39.47] vs. 100.05 [28.94]) compared with BH-VIBE (P = 0.15). In the qualitative analysis, the gated 3D-GRE sequence showed higher scores for depicting focal liver lesions and the sharpness of the hepatic edges (P < 0.0001) but lower subjective overall IQ than did the BH-VIBE (P < 0.01). However, in the patients showing unacceptable BH-VIBE image quality, the degree of improvement of the IQ using the gated-VIBE technique was significantly higher than that seen in the patients showing acceptable BH-VIBE image quality (P < 0.01). T1-weighted gated-VIBE showed technical feasibility for HR-T1WI during HBP imaging of gadoxetic acid-enhanced MRI.