BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosi...BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosis.METHODS A single-center retrospective study was performed in 62 patients with suspected parenchymal liver disease.MR sequences included two-point Dixon,six-point Dixon,MR spectroscopy(MRS)and MR elastography.Fat fraction(FF)estimates on the Dixon techniques were compared to the MRS-proton density FF(PDFF).Statistical tests used included Pearson’s correlation and receiver operating characteristic.RESULTS FF estimates on the Dixon techniques showed excellent correlation(≥0.95)with MRS-PDFF,and excellent accuracy[area under the receiver operating characteristic(AUROC)≥0.95]in:(1)Detecting steatosis;and(2)Grading severe steatosis,(P<0.001).In iron overload,two-point Dixon was not evaluable due to confounding T2*effects.FF estimates on six-point Dixon vs MRS-PDFF showed a moderate correlation(0.82)in iron overload vs an excellent correlation(0.97)without iron overload,(P<0.03).The accuracy of six-point Dixon in grading mild steatosis improved(AUROC:0.59 to 0.99)when iron overload cases were excluded.The excellent correlation(>0.9)between the Dixon techniques vs MRSPDFF did not change in the presence of liver fibrosis(P<0.01).CONCLUSION Dixon techniques performed satisfactorily for the evaluation of hepatic steatosis but with exceptions.展开更多
Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the diff...Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the difference in thigh skeletal muscles between snowboarding halfpipe athletes and healthy volunteers via multiparametric MR imaging.Methods：A comparative study was conducted between 12 healthy volunteers and 14 snowboarding halfpipe athletes.MR scanning targeted the left leg at the level of the proximal thigh on a 3.0T MR system.The measured parameters compared between the two groups included T1,T2,T2＊ relaxation times,fat fraction （FF）,and cross-sectional area （CSA） of the quadriceps femoris and the hamstring muscles.Statistical analysis was carried out using independent sample t-test.Interrater reliability was also assessed with intraclass correlation coefficients （ICCs）.Results：It was statistically equivalent between two groups in age,body mass index,thigh circumference,calf circumference,systolic blood pressure,and resting heart rate （all P ＞ 0.05）.However,the T1 and T2 values of the hamstring muscles in the athlete group were found to be significantly shorter than those in control group （T1：1063.3 ± 24.1 ms vs.1112.0 ± 38.2 ms in biceps femoris,1050.4 ± 31.2 ms vs.1095.0 ± 39.5 ms in semitendinosus,1053.1 ± 31.7 ms vs.1118.4 ± 40.0 ms in semimembranosus,respectively;T2：33.4 ± 0.7 ms vs.36.1 ± 1.9 ms in biceps femoris,34.6 ± 2.0 ms vs.37.0 ± 1.9 ms in semitendinosus,36.9 ± 1.5 ms vs.38.9 ± 2.4 ms in semimembranosus,respectively;all P ＜ 0.05） although T2＊ relaxation time was detected with no significant difference.The FF of the hamstring muscles was obviously less than the control group （5.5 ± 1.9％ vs.10.7 ± 4.7％,P ＜ 0.001）.In addition,the quadriceps＇ CSA in the athlete group was substantially larger than the control group （8039.0 ± 1072.3 vs.6258.2 ± 852.0 mm2,P ＜ 0.001）.Interrater reliability was excellent （ICC：0.758-0.994）.Conclusion：Multiple MR imaging parameters indicated significant differences between snowboarding halfpipe athletes and healthy volunteers in the thigh skeletal muscles.展开更多
文摘BACKGROUND Hepatic steatosis is a very common problem worldwide.AIM To assess the performance of two-and six-point Dixon magnetic resonance(MR)techniques in the detection,quantification and grading of hepatic steatosis.METHODS A single-center retrospective study was performed in 62 patients with suspected parenchymal liver disease.MR sequences included two-point Dixon,six-point Dixon,MR spectroscopy(MRS)and MR elastography.Fat fraction(FF)estimates on the Dixon techniques were compared to the MRS-proton density FF(PDFF).Statistical tests used included Pearson’s correlation and receiver operating characteristic.RESULTS FF estimates on the Dixon techniques showed excellent correlation(≥0.95)with MRS-PDFF,and excellent accuracy[area under the receiver operating characteristic(AUROC)≥0.95]in:(1)Detecting steatosis;and(2)Grading severe steatosis,(P<0.001).In iron overload,two-point Dixon was not evaluable due to confounding T2*effects.FF estimates on six-point Dixon vs MRS-PDFF showed a moderate correlation(0.82)in iron overload vs an excellent correlation(0.97)without iron overload,(P<0.03).The accuracy of six-point Dixon in grading mild steatosis improved(AUROC:0.59 to 0.99)when iron overload cases were excluded.The excellent correlation(>0.9)between the Dixon techniques vs MRSPDFF did not change in the presence of liver fibrosis(P<0.01).CONCLUSION Dixon techniques performed satisfactorily for the evaluation of hepatic steatosis but with exceptions.
基金This work was supported by grants from the National Key Research and Development Program of China （No. 2016YFC0107102） and the National Natural Science Foundation of China （No. 30871211 and No. 81271538）.
文摘Background：Magnetic resonance （MR） imaging provides a unique,noninvasive diagnostic platform to quantify the physiological and biochemical variables of skeletal muscle at rest.This study was to investigate the difference in thigh skeletal muscles between snowboarding halfpipe athletes and healthy volunteers via multiparametric MR imaging.Methods：A comparative study was conducted between 12 healthy volunteers and 14 snowboarding halfpipe athletes.MR scanning targeted the left leg at the level of the proximal thigh on a 3.0T MR system.The measured parameters compared between the two groups included T1,T2,T2＊ relaxation times,fat fraction （FF）,and cross-sectional area （CSA） of the quadriceps femoris and the hamstring muscles.Statistical analysis was carried out using independent sample t-test.Interrater reliability was also assessed with intraclass correlation coefficients （ICCs）.Results：It was statistically equivalent between two groups in age,body mass index,thigh circumference,calf circumference,systolic blood pressure,and resting heart rate （all P ＞ 0.05）.However,the T1 and T2 values of the hamstring muscles in the athlete group were found to be significantly shorter than those in control group （T1：1063.3 ± 24.1 ms vs.1112.0 ± 38.2 ms in biceps femoris,1050.4 ± 31.2 ms vs.1095.0 ± 39.5 ms in semitendinosus,1053.1 ± 31.7 ms vs.1118.4 ± 40.0 ms in semimembranosus,respectively;T2：33.4 ± 0.7 ms vs.36.1 ± 1.9 ms in biceps femoris,34.6 ± 2.0 ms vs.37.0 ± 1.9 ms in semitendinosus,36.9 ± 1.5 ms vs.38.9 ± 2.4 ms in semimembranosus,respectively;all P ＜ 0.05） although T2＊ relaxation time was detected with no significant difference.The FF of the hamstring muscles was obviously less than the control group （5.5 ± 1.9％ vs.10.7 ± 4.7％,P ＜ 0.001）.In addition,the quadriceps＇ CSA in the athlete group was substantially larger than the control group （8039.0 ± 1072.3 vs.6258.2 ± 852.0 mm2,P ＜ 0.001）.Interrater reliability was excellent （ICC：0.758-0.994）.Conclusion：Multiple MR imaging parameters indicated significant differences between snowboarding halfpipe athletes and healthy volunteers in the thigh skeletal muscles.
