Objective To explore the value of proton density fat fraction(PDFF)and R2* based on iterative decomposition of water and fat with echo asymmetry and least squares estimation quantification(IDEAL-IQ)sequence in the assessment of vertebral fat and trabecular structure in postmenopausal women with osteoporosis.Methods A total of 85 postmenopausal women who underwent abdominal CT scans were selected and divided into three groups using quantitative computed tomography(QCT):osteoporosis group(30 cases),osteopenia group(29 cases),and normal bone mass group(26 cases).MRI examinations were performed within 2 weeks,the sequences including lumbar sagittal IDEAL-IQ and T2* mapping.The images were uploaded to the post-processing workstation,and the mean PDFF,IDEAL-R2* and gradient echo(GRE)-R2* were calculated for the L1-L5 vertebral body.One-way ANOVA was used to analyze the differences between the parameters among the three groups,and Spearman was used to compare the correlations between PDFF and bone mineral density(BMD),R2* value,as well as BMD and R2* value.The Bland-Altman plot was drawn to evaluate the consistency of IDEAL-R2* and GRE-R2*,and the receiver operating characteristic(ROC)curve was used to further evaluate the diagnostic performance of PDFF and R2* values for osteoporosis and osteopenia.Results There were significant differences in PDFF and BMD values among normal bone mass group,osteopenia group and osteoporosis group(P＜0.05),and R2* values were reduced in the osteoporosis group compared to the normal bone mass group(P＜0.05).Correlation analysis showed that PDFF was negatively correlated with BMD(r=-0.558,P＜0.05),negatively correlated with R2*[r=-0.250(IDEAL),-0.354(GRE),both P＜0.05],and positively correlated with BMD and R2*[r=0.351(IDEAL),0.457(GRE),both P＜0.05].The Bland-Altman plots showed that the mean value of the difference between IDEAL-R2* and GRE-R2* was-4.5 Hz,and the results were highly consistent.ROC curves showed no significant difference in the diagnostic efficacy of IDEAL-R2* and GRE-R2* in the assessment of osteoporosis and osteopenia(Z=0.526,1.327,P=0.599,0.185),but the diagnostic efficacy of both was lower than PDFF[area under the curve(AUC)=0.846(osteoporosis),0.684(oseopenia)].Conclusion IDEAL-IQ sequence-derived PDFF and R2* values are effective biological indicators for one-stop assessment of vertebral fat and microscopic trabecular structure in osteoporosis,which have certain clinical value.

Objective To explore the value of proton density fat fraction(PDFF)and R2* based on iterative decomposition of water and fat with echo asymmetry and least squares estimation quantification(IDEAL-IQ)sequence in the assessment of vertebral fat and trabecular structure in postmenopausal women with osteoporosis.Methods A total of 85 postmenopausal women who underwent abdominal CT scans were selected and divided into three groups using quantitative computed tomography(QCT):osteoporosis group(30 cases),osteopenia group(29 cases),and normal bone mass group(26 cases).MRI examinations were performed within 2 weeks,the sequences including lumbar sagittal IDEAL-IQ and T2* mapping.The images were uploaded to the post-processing workstation,and the mean PDFF,IDEAL-R2* and gradient echo(GRE)-R2* were calculated for the L1-L5 vertebral body.One-way ANOVA was used to analyze the differences between the parameters among the three groups,and Spearman was used to compare the correlations between PDFF and bone mineral density(BMD),R2* value,as well as BMD and R2* value.The Bland-Altman plot was drawn to evaluate the consistency of IDEAL-R2* and GRE-R2*,and the receiver operating characteristic(ROC)curve was used to further evaluate the diagnostic performance of PDFF and R2* values for osteoporosis and osteopenia.Results There were significant differences in PDFF and BMD values among normal bone mass group,osteopenia group and osteoporosis group(P＜0.05),and R2* values were reduced in the osteoporosis group compared to the normal bone mass group(P＜0.05).Correlation analysis showed that PDFF was negatively correlated with BMD(r=-0.558,P＜0.05),negatively correlated with R2*[r=-0.250(IDEAL),-0.354(GRE),both P＜0.05],and positively correlated with BMD and R2*[r=0.351(IDEAL),0.457(GRE),both P＜0.05].The Bland-Altman plots showed that the mean value of the difference between IDEAL-R2* and GRE-R2* was-4.5 Hz,and the results were highly consistent.ROC curves showed no significant difference in the diagnostic efficacy of IDEAL-R2* and GRE-R2* in the assessment of osteoporosis and osteopenia(Z=0.526,1.327,P=0.599,0.185),but the diagnostic efficacy of both was lower than PDFF[area under the curve(AUC)=0.846(osteoporosis),0.684(oseopenia)].Conclusion IDEAL-IQ sequence-derived PDFF and R2* values are effective biological indicators for one-stop assessment of vertebral fat and microscopic trabecular structure in osteoporosis,which have certain clinical value.