| Partâ… multiple linear stepwise regression of liver lipid levels and Correlation AnalysisObjectives:To analyze the correlations between liver Lip2 contents and its Influencing factors, correlative metabolites of lipids for liver 3.0T 1H-MRS. Materials and methods:The prospective study of liver 1H-MRS was performed with a GE Signa Excite HD 3.0 T system and eight-channel torso phased-array coils using PRESS sequence.62 volunteers were enrolled in this study. Liver spectra were collected with a TR of 1500 ms,TE of 30ms, VOI of 2 cm×2 cm×2 cm, NSA of 64 times. All data were processed using Spearman rank correlation analysis and multiple linear stepwise regression. Results:weight(r=0.533, P<0.001),age(r=0.400, P=0.008),body mass index(r=0.587, P<0.001),water suppression rate(r=-0.543, P<0.001),the signal amplitude of Lip1(r=0.582,P=0.003),the signal amplitude of Lip2(r=0.927,P<0.001),the signal amplitude of Lip3(r=0.910,P<0.001),the signal amplitude of Lip4(r=0.810,P<0.001),the signal integrated area of Lip3(r=0.610, P<0.001),the signal integrated area of Lip4(r=0.524,P=0.002)。group with lower Lip2 has lower weight(58.3±12.5 kg,67.3±8.8 kg, t=-2.073, P=0.045),lower BMI (21.3±3.1 kg/(m)2,24.7±2.8 kg/(m)2, t=-3.771, P=0.001),younger age (34.3±12.2 years,45.7±10.5 years, t=-3.236, P=0.002), better water suppression effect(16.6±2.7Hz,19.2±5.0 Hz, t=-2.073, P=0.045).Conclusion:(1) Body mass index had most close relationship with Lip2 content, with increase content of Lip2,contents of Lip1,Lip3 and Lip4 also increase, However, there were not consistent correlation degree. Lipid accumulation in the liver could be the result of the increased fat portion of the body depending on age and weight. (2) liver lipid content prediction equation was as follows=2.911-(0.030×water suppression)+ (0.009×Linewidth)Part II Exploration of Influencing Factors on Shimming and Water Suppression for in vivo Liver 3.0T 1H-MRSObjectives:To discuss the clinical factors which influence water suppression and auto-shimming line width for liver 3.0T 1H-MRS. Materials and methods:TThe prospective study of liver 1H-MRS was performed with a GE Signa Excite HD 3.0 T system and eight-channel torso phased-array coils using PRESS sequence.62 volunteers were enrolled in this study. Liver spectra were collected with a TR of 1500 ms,TE of 30ms, VOI of 2 cm×2 cm×2 cm, NSA of 64 times. All data were processed using Spearman rank correlation analysis and independent t test to analyze whether general condition(height, weight, body mass index etc.between different water suppression effect groups and between different shimming effect groups exist significance difference. Using Chi-square test to analyze whether water suppression rate and auto-shimming line width between fatty liver groups and non-fatty liver exist significance difference Results:Weight and WS(-0.490, P<0.001),BMI and WS(-0.502, P<0.001).the lower weight group has smaller height (162.2.±8.2cm,169.2±5.9cm, t=-3.826, P＜0.000), smaller BMI (20.9±2.1 kg /(m)2,25.2±2.3 kg/(m)2, t=-7.722, P<0.000), smaller lw(17.2±3.6 Hz,20.2±5.2 Hz, t=-2.619, P=0.011)。better ws(min-max 90-96%,65-96%; median94%,92%; Z=-3.019, P=0.003)。less lipid content(min-max 0.00-0.44,0.00-0.96;median:0.01, 0.04)(Z=-2.833, P=0.005)。lower BMI group(56.3±7.9 kg,71.0±8.6 kg, t=-6.980, P<0.000), better ws (min-max 90-96%,65-96%; median:94%,92%; Z=-3.304, P=0.001)。less lipid content (min-max0.00-0.44,0.00-0.96; median 0.01,0.08) (Z=-3.785, P＜0.000).(2)age and lipid content (0.296,P=0.021).The rate of LW<20 in group fatty liver and in group non-fatty liver were 38.5% and 87.8% respectively. OR=5.550. The rate of WS< 90% in group fatty liver and in group fatty liver were 46.2% and 0%, respectively. By comparison group with WS>90% and group with WS<90%,we found that the former average height, weight, BMI and LW is smaller than the latter. By comparison group with LW<20 and group with LW>20,we found that the former water suppression rate is better than the latter. Conclusion:Hepatic steatosis may exert an adverse effect in water suppression and shimming.Part III The effect of intravenous Gd-DTPA and saturated zone on hepatic and kidney proton 3.0T MRS shimming and water suppressionObjective To evaluate the effect of intravenous Gd—DTPA and saturated zone on hepatic and kidney proton MRS water suppression and shimming at 3.0 T. Methods The prospective study of proton MRS was performed with a GE Signa Excite HD 3.0 T system and eight-channel phased-array coils using PRESS sequence. Hepatic spectra prescan were collected with a TR of 1500 ms, TE of 30 ms, ROI of 2 cm×2 cm×2 cm, NSA of 64 times. The data were analyzed with the paired t test(liver) or Wilcoxon Signed Ranks Test(kidney). Results (1) Before administration of contrast medium, saturated zone is helpful for effective water suppression (94.0%,93.2%, t=-3.763, P=0.001). After administration of contrast medium, saturated zone is also helpful for effective water suppression(91.2%,88.9%, t=-10.811,P<0.000). Before and after administration of contrast medium, there were poor water suppression(91.2%,94.0%, t=8.649, P<0.000) and shimming (20.6±5.7 Hz,19.5±5.8 Hz, t=-2.137,P=0.041) of liver. (2) Before administration of contrast medium, saturated zone is helpful for effective shimming(Z=-2.801, P=0.005) and water suppression(Z=-2.880, P=0.004). After administration of contrast medium, saturated zone is also helpful for effective shimming(Z=-4.434, P<0.000) and water suppression(Z=-4.709, P＜0.000). Before and after administration of contrast medium, there were poor water suppression and shimming of kidney. Conclusion It is better to acquire MRS data before administration of contrast medium in liver and kidney with saturated zone.
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