PURPOSE: We sought to optimize scanning parameters for MR elastography at 3.0 T clinical unit. MATERIALS AND METHODS: 10 volunteers were scanned with various magnetization encoding gradient (MEG) frequencies from 60 to 120 Hz at every 10 Hz, with otherwise fixed parameters (external driver frequency/amplitude = 60 Hz/50 %, 10 mm slice thickness, etc.). Images were qualitatively assessed for the degree of image defects, and also quantitatively for the areas without cross-hatching. After determining optimal MEG frequency, external driver amplitudes of 70 % (vs 50 %) and slice thickness of 8 mm (vs 10 mm) were also tested. With the optimized parameters, scans were repeated 1 week after the initial scan, and the repeatability of the liver stiffness measurement was validated. RESULTS: 80 or 90 Hz was shown to be the best MEG frequency. There were no significant differences in the qualitative and quantitative assessment between the two amplitudes and two slice thicknesses; however, 70 % amplitude resulted in discomfort at the chest wall beneath the external acoustic driver. Thus, MEG 80 (or 90) Hz, amplitude 50 %, and thickness 10 (or 8) mm were considered optimal. Repeatability of the liver stiffness measurement was ±10 % (95 % confidence interval). CONCLUSIONS: With the optimized parameters, repeatability of ±10 % in liver stiffness measurement was obtained.
PURPOSE: We sought to optimize scanning parameters for MR elastography at 3.0 T clinical unit. MATERIALS AND METHODS: 10 volunteers were scanned with various magnetization encoding gradient (MEG) frequencies from 60 to 120 Hz at every 10 Hz, with otherwise fixed parameters (external driver frequency/amplitude = 60 Hz/50 %, 10 mm slice thickness, etc.). Images were qualitatively assessed for the degree of image defects, and also quantitatively for the areas without cross-hatching. After determining optimal MEG frequency, external driver amplitudes of 70 % (vs 50 %) and slice thickness of 8 mm (vs 10 mm) were also tested. With the optimized parameters, scans were repeated 1 week after the initial scan, and the repeatability of the liver stiffness measurement was validated. RESULTS: 80 or 90 Hz was shown to be the best MEG frequency. There were no significant differences in the qualitative and quantitative assessment between the two amplitudes and two slice thicknesses; however, 70 % amplitude resulted in discomfort at the chest wall beneath the external acoustic driver. Thus, MEG 80 (or 90) Hz, amplitude 50 %, and thickness 10 (or 8) mm were considered optimal. Repeatability of the liver stiffness measurement was ±10 % (95 % confidence interval). CONCLUSIONS: With the optimized parameters, repeatability of ±10 % in liver stiffness measurement was obtained.
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