Value and significance of T2*-corrected modified multi-echo Dixon technique in quantitative bone marrow fat assessment of children with acute leukemia
Objective To measure the bone marrow fat fraction(FF)of lower lumbar vertebrae,ilium and upper femur of children with acute leukemia(AL)using T2*-corrected modified multi-echo Dixon(m-Dixon),and to explore the relationship between bone marrow FF and bone marrow infiltration of AL children.Methods Fifty-five pediatric patients with AL were treated in the First Affiliated Hospital of Zhengzhou University from April 2020 to December 2022(AL group),while another 55 children with no AL underwent lumbar spine and pelvis MRI scan during the same period(control group).Both groups underwent MRI m-Dixon sequence to measure the bone marrow FFs of L3,L4,ilium and upper femur.AL group was divided into acute lymphocytic leukemia(ALL)group(n=35)and acute myeloid leukemia(AML)group(n=20)according to the bone marrow cytology examination results.The gender ratio,age and FFs of L3,L4,ilium and upper femur between AL and control group,and the FFs at different measurement sites in AL group and control group were compared.The FFs of L3,L4,ilium and upper femur,and proportion of immature cells were compared between ALL group and AML group.Pearson correlation method was used to analyze the correlation between FFs of 4 sites and the proportion of immature cells in AML and ALL groups.Results(1)There were no significant differences in the gender ratio and age between AL group and control group(P＞0.05).The FFs of L3,L4,ilium and upper femur were lower in AL group[2.20(0.97,3.83)％,1.49(0.74,5.05)％,2.32(0.86,4.38)％,2.39(1.12,4.65)％]than those in control group[37.39(33.38,46.32)％,39.85(36.07,47.05)％,55.07(51.24,57.99)％,61.08(57.11,66.76)％](P＜0.05).In control group,the FFs were higher in the ilium and upper femur than those in L3 and L4(P＜0.05),the FF was higher in the upper femur than that in the ilium(P＜0.05),and there was no significant difference in the FF between L3 and L4(P＞0.05).There were no significant differences in FFs among L3,L4,ilium and upper femur in AL group(P＞0.05).(2)There were no significant differences in the FFs of L3,L4,ilium and upper femur between ALL and AML groups(P＞0.05).The proportion of immature cells of bone marrow was higher in ALL group[(91.41±8.33)％]than that in AML group[(70.36±22.73)％](t=3.992,P=0.001).(3)There was no correlation between the mean FFs of 4 sites[(2.83±2.09)％]and the proportion of bone marrow immature cells in ALL group(r=-0.151,P=0.387),while there was a negative correlation between the mean FFs of 4 sites[(5.35± 5.07)％]and the proportion of bone marrow immature cells in AML group(r=-0.573,P=0.008).Conclusions The bone marrow fat content reduces in the lower lumbar vertebrae,ilium and upper femur of children with AL,and is negatively correlated with the proportion of immature cells of bone marrow in AML patients.MRI m-Dixon technique can quantitatively evaluate the degree of bone marrow infiltration in AL patients.
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