BACKGROUND R2^(*)estimation reflects the paramagnetism of the tumor tissue,which may be used to differentiate between benign and malignant liver lesions when contrast agents are contraindicated.AIM To investigate whet...BACKGROUND R2^(*)estimation reflects the paramagnetism of the tumor tissue,which may be used to differentiate between benign and malignant liver lesions when contrast agents are contraindicated.AIM To investigate whether R2^(*)derived from multi-echo Dixon imaging can aid differentiating benign from malignant focal liver lesions(FLLs)and the impact of 2D region of interest(2D-ROI)and volume of interest(VOI)on the outcomes.METHODS We retrospectively enrolled 73 patients with 108 benign or malignant FLLs.All patients underwent conventional abdominal magnetic resonance imaging and multi-echo Dixon imaging.Two radiologists independently measured the mean R2^(*)values of lesions using 2D-ROI and VOI approaches.The Bland-Altman plot was used to determine the interobserver agreement between R2^(*)measurements.Intraclass correlation coefficient(ICC)was used to determine the reliability between the two readers.Mean R2^(*)values were compared between benign and malignant FFLs using the nonparametric Mann-Whitney test.Receiver operating characteristic curve analysis was used to determine the diagnostic performance of R2^(*)in differentiation between benign and malignant FFLs.We compared the diagnostic performance of R2^(*)measured by 2D-ROI and VOI approaches.RESULTS This study included 30 benign and 78 malignant FLLs.The interobserver reproducibility of R2^(*)measurements was excellent for the 2D-ROI(ICC=0.994)and VOI(ICC=0.998)methods.Bland-Altman analysis also demonstrated excellent agreement.Mean R2^(*)was significantly higher for malignant than benign FFLs as measured by 2D-ROI(P<0.001)and VOI(P<0.001).The area under the curve(AUC)of R2^(*)measured by 2D-ROI was 0.884 at a cut-off of 25.2/s,with a sensitivity of 84.6%and specificity of 80.0%for differentiating benign from malignant FFLs.R2^(*)measured by VOI yielded an AUC of 0.875 at a cut-off of 26.7/s in distinguishing benign from malignant FFLs,with a sensitivity of 85.9%and specificity of 76.7%.The AUCs of R2^(*)were not significantly different between the 2D-ROI and VOI methods.CONCLUSION R2^(*)derived from multi-echo Dixon imaging whether by 2D-ROI or VOI can aid in differentiation between benign and malignant FLLs.展开更多
By means of an improved ligand-field theory, the ＂pure electronic＂ PS and the PS due to EPI of R line of MgO： V^2＋ have been calculated, respectively. The calculated results are in very good agreement with the exp...By means of an improved ligand-field theory, the ＂pure electronic＂ PS and the PS due to EPI of R line of MgO： V^2＋ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R line of MgO：V^2＋ and the PS of its R line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R line, which has satisfactorily explained the experimental results. The mixing-degree of ｜t2^2（^3T1）e^4T2〉 and ｜t2^3 ^2E〉 in the wavefunetion of R level and its variation with pressure have been calculated and analyzed. The comparison between the feature of R-line PS of MgO：V^2＋ and that of MgO：Cr^3＋ has been made.展开更多
文摘BACKGROUND R2^(*)estimation reflects the paramagnetism of the tumor tissue,which may be used to differentiate between benign and malignant liver lesions when contrast agents are contraindicated.AIM To investigate whether R2^(*)derived from multi-echo Dixon imaging can aid differentiating benign from malignant focal liver lesions(FLLs)and the impact of 2D region of interest(2D-ROI)and volume of interest(VOI)on the outcomes.METHODS We retrospectively enrolled 73 patients with 108 benign or malignant FLLs.All patients underwent conventional abdominal magnetic resonance imaging and multi-echo Dixon imaging.Two radiologists independently measured the mean R2^(*)values of lesions using 2D-ROI and VOI approaches.The Bland-Altman plot was used to determine the interobserver agreement between R2^(*)measurements.Intraclass correlation coefficient(ICC)was used to determine the reliability between the two readers.Mean R2^(*)values were compared between benign and malignant FFLs using the nonparametric Mann-Whitney test.Receiver operating characteristic curve analysis was used to determine the diagnostic performance of R2^(*)in differentiation between benign and malignant FFLs.We compared the diagnostic performance of R2^(*)measured by 2D-ROI and VOI approaches.RESULTS This study included 30 benign and 78 malignant FLLs.The interobserver reproducibility of R2^(*)measurements was excellent for the 2D-ROI(ICC=0.994)and VOI(ICC=0.998)methods.Bland-Altman analysis also demonstrated excellent agreement.Mean R2^(*)was significantly higher for malignant than benign FFLs as measured by 2D-ROI(P<0.001)and VOI(P<0.001).The area under the curve(AUC)of R2^(*)measured by 2D-ROI was 0.884 at a cut-off of 25.2/s,with a sensitivity of 84.6%and specificity of 80.0%for differentiating benign from malignant FFLs.R2^(*)measured by VOI yielded an AUC of 0.875 at a cut-off of 26.7/s in distinguishing benign from malignant FFLs,with a sensitivity of 85.9%and specificity of 76.7%.The AUCs of R2^(*)were not significantly different between the 2D-ROI and VOI methods.CONCLUSION R2^(*)derived from multi-echo Dixon imaging whether by 2D-ROI or VOI can aid in differentiation between benign and malignant FLLs.
文摘By means of an improved ligand-field theory, the ＂pure electronic＂ PS and the PS due to EPI of R line of MgO： V^2＋ have been calculated, respectively. The calculated results are in very good agreement with the experimental data. The behaviors of the pure electronic PS of R line of MgO：V^2＋ and the PS of its R line due to EPI are different. It is the combined effect of them that gives rise to the total PS of R line, which has satisfactorily explained the experimental results. The mixing-degree of ｜t2^2（^3T1）e^4T2〉 and ｜t2^3 ^2E〉 in the wavefunetion of R level and its variation with pressure have been calculated and analyzed. The comparison between the feature of R-line PS of MgO：V^2＋ and that of MgO：Cr^3＋ has been made.
