正常小儿肛门横纹肌复合体发育状态的MRI观察及临床意义

Quantification of striated muscle complex in normal children with magnetic resonance imaging

目的建立小儿直肠肛门周围横纹肌复合体发育的正常客观指标。方法住院儿童25例(没有直肠肛管疾病),男15例,女10例,平均年龄3.2岁(3个月～14岁)。采用1.5TMR成像仪,体部相控阵列线圈(新生儿和婴儿则用头部线圈),常规行冠状、横断及矢状位扫描,观察并定量测量耻骨直肠肌(puborectalis,PR)和肛门外括约肌(externalanalsphincter,EAS)发育宽度、长度的绝对、相对值。结果14岁以下小儿肌肉的长度的相对值PR为(0.47±0.04)、EAS为(0.41±0.04),宽度的相对值PR为(0.50±0.04)、EAS为(0.44±0.04)。EAS、PR宽度、长度的绝对值与年龄有高度相关性(P<0.05),宽度、长度的相对值与年龄无相关性(P>0.05)。结论随年龄的增长PR、EAS长度和宽度的绝对值在不断增加,不能用于个体间的相互比较。而长度和宽度的相对值变化不明显,可以作为小儿生长发育时期肌肉发育的正常标准。

Objective To establish the normal values of striated muscle complex (SMC) in children with phased-array magnetic resonance imaging (MRI). Methods MRI was performed in 15 boys and 14 girls (ranged 3 months to 14 years, average (3.2) years) without anorectal diseases. The dimensions of the puborectalis (PR) and external anal sphincter (EAS) were measured in different planes. Results The absolute values of width and length of PR and EAS were closely correlation with age (P<(0.05)). However, the relative values of width and length of PR and EAS had no relationship with age (P>(0.05)). The values of relative length of PR and posterior EAS were ((0.47)±(0.04)) and ((0.41)±(0.04)), respectively. And the values of relative width of PR and posterior EAS were ((0.50)±(0.04)) and ((0.44)±(0.04)), respectively. Conclusions The values of relative width and length of PR and EAS deserve to be objective criteria for evaluation of SMC in children less than 14 years of age.