磁共振扩散张量成像对正常女性尿道括约肌复合体及肛提肌结构的分析研究

Analysis of the structure of normal female urethral sphincter complex and levator ani muscles by magnetic resonance diffusion tensor imaging

目的利用3.0 T MR扩散张量成像(diffusion tensor imaging,DTI)技术探讨分娩和年龄对正常女性尿道括约肌复合体及肛提肌结构的影响变化,为分析盆底功能障碍的发病机制提供客观依据。材料与方法前瞻性纳入103例无盆底功能障碍的女性志愿者,根据有无分娩史分为正常对照组24例和经产妇组79例,然后再将经产妇组按年龄段分为≤30岁组(19例)、31~44岁组(22例)、45~59岁组(27例)和≥60岁组(11例)四个亚组。采用二维扩散加权横断自旋梯度回波(spin-echo-gradient-recalled echo,SE-GRE)脉冲序列对所有受试者行盆底DTI检查,测量尿道中段环形括约肌、纵行肌、耻骨直肠肌及髂尾肌肌纤维的DTI参数,包括各向异性分数(fractional anisotropy,FA)、表观扩散系数(apparent diffusion coefficient,ADC)值、三个特征值(λ1,λ2,λ3),分析分娩史及不同年龄对尿道及肛提肌的微观组织结构的影响。结果(1)经产妇组中≤30岁组耻骨直肠肌FA值较正常对照组小,差异有统计学意义(t=2.206,P=0.030);(2)经产妇组中不同年龄组间尿道中段环形括约肌ADC值、λ2值及λ3值之间比较,差异均有统计学意义(F=3.547、4.105、3.596,P=0.018、0.009、0.017),尿道中段纵行肌DTI各参数比较,差异无统计学意义(P>0.05);(3)经产妇组中不同年龄组间耻骨直肠肌FA值、ADC值、λ1值及λ2值之间比较,差异均有统计学意义(F=8.071、6.051、6.672、3.688,P<0.001、P=0.001、P<0.001、P=0.013);(4)经产妇组中不同年龄组间髂尾肌FA值、ADC值及λ3值之间比较,差异均有统计学意义(F=5.676、3.110、5.175,P=0.001、0.028、0.002)。结论分娩史主要影响耻骨直肠肌的微观结构,年龄因素对尿道环形括约肌及肛提肌微观结构的改变有一定的影响,DTI技术对观察盆底肌结构和评估微结构变化具有重要价值。

Objective:To explore the influence of delivery and age on the microtissue structure of urethral sphincter complex and levator ani muscles in normal female by 3.0 T MR diffusion tensor imaging,and to provide an objective basis for analyzing the pathogenesis of pelvic floor dysfunction.Materials and Methods:Prospectively,103 women without pelvic floor dysfunction were collected and divided into 24 cases in the normal control group and 79 cases in the menstrual group based on the presence or absence of the history of delivery,and then the menstrual group was divided by age group into those≤30 years(19 cases),31-44 years(22 cases),45-59 years(27cases)and≥60 years old group(11 cases).A two-dimensional diffusion-weighted transverse spin-gradient echo(SE-GRE)pulse sequence was used to perform pelvic floor diffusion tensor imaging(DTI)in all subjects,and DTI parameters,including fraction anisotropy(FA),apparent diffusion coefficient(ADC)values,and three eigenvalues(λ1,λ2,andλ3)were measured in the middle urethral circle sphincter,longitudinal muscle,puborectalis muscle,and iliococcygeus muscle fibers to.analyze the effects of delivery history and different age groups on the microstructure of the urethra and levator ani muscles.Results:(1)The FA value of the puborectalis muscle in the group under 30 years was smaller than that of the normal control group in the menstrual group,and the difference was statistically significant(t=2.206,P=0.030);(2)There was a statistically significant difference between ADC values,λ2 values andλ3 values of the middle urethral ring sphincter between different age groups in the transmaternal group(F=3.547,4.105,3.596,P=0.018,0.009,0.017),but there was no statistically significant difference in the DTI parameters of the longitudinal muscle of the middle urethra(P>0.05);(3)In the multiparous women group,the FA value,ADC value,λ1 value andλ2 value of the puborectalis muscle were compared between different age groups,and the differences were statistically significant(F=8.071,6.051,6.672,3.688,P<0.001,P=0.001,P<0.001,P=0.013);(4)In the multiparous female group,the FA value,ADC value andλ3 value of the iliococcygeus muscle were compared between different age groups,and the differences were statistically significant(F=5.676,3.110,5.175,P=0.001,0.028,0.002).Conclusions:Delivery mainly affects the microstructure of the puborectalis muscle,the age factor has a certain influence on the microstructure changes of the urethral annular sphincter and levator ani muscles.DTI technology is of great value in observing the pelvic floor muscle structure and evaluating the microstructure changes.