MR IDEAL-IQ脂肪定量技术评价进行性假肥大性肌营养不良患儿骨骼肌脂肪浸润程度

目的采用MR基于最小二乘估算法和不对称回波迭代分解的水脂分离(IDEAL-IQ)脂肪定量技术评估进行性假肥大性肌营养不良(DMD)患儿臀部及大腿骨骼肌脂肪浸润程度,观察脂肪分数(FF)与临床资料的相关性。方法纳入89例经病理学和/或基因检测确诊的DMD患儿,记录其臀部及双侧大腿MR T1WI及IDEAL-IQ数据。对T1WI所见肌肉脂肪浸润程度进行主观评分,测量IDEAL-IQ序列脂肪定量图中各肌肉FF,观察DMD累及大腿肌肉规律;采用Spearman相关性分析评价大腿肌肉FF与主观评分、患儿年龄、总肌力评分及肌酸激酶(CK)水平的相关性。结果主观评分与脂肪定量均显示,DMD患儿臀大肌及大收肌受累最重,其次为股四头肌及股二头肌等,闭孔内肌、闭孔外肌、长收肌及短收肌等受累较轻。各肌肉FF与主观评分结果均呈正相关(r=0.24~0.92,P均<0.05);肌肉FF总和与年龄呈正相关(r=0.73,P<0.01),与总肌力评分呈负相关(r=-0.82,P<0.01),与CK水平无显著相关性(P>0.05)。结论MR IDEAL-IQ脂肪定量技术可显示DMD患儿臀部及大腿肌肉脂肪浸润程度;臀大肌、大收肌、股四头肌受累较重,其程度与患儿年龄和肌力存在相关性。

MR IDEAL-IQ fat quantification technique for evaluation on skeletal muscle fat infiltration degree in children with Duchenne muscular dystrophy

Objective To observe skeletal muscle fat infiltration degree in Duchenne muscular dystrophy (DMD) children with MR iterative decomposition of water and fat with echo asymmetry and least square estimation-iron quantification (IDEAL-IQ) technique, and to explore the correlations of fat fraction (FF) and clinical data. Methods Eighty-nine children with DMD diagnosed with pathology and/or genetic testing were enrolled, and MR T1WI and IDEAL-IQ data of buttocks and bilateral thighs were recorded. The fat infiltration degrees of muscles on T1WI were scored subjectively, and the FF of each muscle on IDEAL-IQ sequence fat quantitative map was measured. The regularity of thigh muscle involvement in children with DMD was explored. Spearman correlation analysis was used to evaluate the correlations of FF of thigh muscles and subjective score, age, total muscle strength score and creatine kinase (CK) level. Results Both subjective scoring and fat quantification showed that the gluteus maximus and adductor magnus were most affected, followed by quadriceps femoris and biceps femoris, and obturator internus, obturator externus, adductor longus and adductor brevis were less affected. FF of each muscle was positively correlated with subjective score (r=0.24-0.92, all P<0.05). The sum of muscle FF was positively correlated with age (r=0.73, P<0.01) but negatively correlated with total muscle strength score (r=-0.82, P<0.01), and there was no significant correlation with CK level (P>0.05). Conclusion MR IDEAL-IQ fat quantification technique could be used to evaluate the degree of fat infiltration in hip and thigh muscles of children with DMD. The most severely infiltrated muscles included gluteus maximus, adductor magnus quadriceps femoris and biceps femoris, and skeletal muscle fat infiltration degrees were correlated with patients'' age and myodynamia.