Fat Content In Lumbar Paravertebral Muscles:Quantitative And Qualitative Analysis Using Dual-Energy CT In Correlation To MR Imaging

Backgroud:Studies have reported that dual-energy computed tomography(dual-energy CT)can quantify fat content in the liver and rotator cuff,but whether dual-energy CT can accurately identify and quantify fat infiltration in the paravertebral muscle remains to be determined.Purpose:This study aims to assess the diagnostic performance of dual-energy computed tomography(dual-energy CT)on lumbar paravertebral muscles fat infiltration in participants with low back pain.Method:In this prospective study,21 participants with low back pain were performed with noncontrast dual-energy CT scans within 1 week after magnetic resonance(MR)examinations.The assessment was based on the selected region of interest obtained from the paravertebral L1/L2L5/S1 muscle.On visual evaluation,lumbar paravertebral muscles fat infiltration was assessed at dual-energy CT virtual monoenergetic images(80 keV)with Goutallier classification system using MR results as a reference.Quantitative parameters fat fraction,CT number,ΔCT number(difference of CT number at 140 and 80 keV),and optimal cutoff values above the indicators between MR adjacent grades were measured.Results:In this study,582 ROIs from 21 participants(mean age,60±16 years old;15 females)were evaluated.Sensitivity,specificity,and accuracy of readers 1 and 2 at severe grade(grades 3 and 4)were 67%and 85%(22 and 28 of 33),99%and 99%(159 and 160 of 161),and 93%and 97%(181 and 188 of 194),respectively.Interobserver reliability was high with κ=0.85(p<0.001).For dual-energy CT quantification parameters,significance was all represented between five grades(all p<0.01).The area under the curve of indicators for discrimination between severe(grades 3 and 4)and normal and moderate(grades 0,1,and 2)grades were>0.80(p<0.001).The correlation coefficients between dual-energy CT and MR quantitative fat content were 0.67(FF),-0.67(CT value)and 0.67(ΔCT value),respectively,and all p<0.001.Conclusions:dual-energy CT was a promising qualitative and quantitative imaging technique to assess lumbar paravertebral muscles fat infiltration in participants with low back pain and could provide accurate quantification for different fat infiltration degrees.Moreover,visual dualenergy CT assessment could excellently distinguish severe from normal and moderate fat infiltration of MR grades.