Abstract: Background   It has been reported that the changes of pelvic floor after radical hysterectomy is one of the most important reason for postoperative pelvic floor dysfunctions. However，there are few reports on the changes in postoperative levator ani muscles.Objective　To evaluate the changes in levator ani muscle before and after radical hysterectomy with reconstruction of 3D dynamic MRI，providing a theoretical reference for the understanding of postoperative pelvic floor disorders.Methods　According to the inclusion criteria，33 cases underwent radical hysterectomy due to stageⅠA2-ⅡA2 squamous carcinoma of the cervix in Nanfang Hospital，Southern Medical University during September 2015 to September 2017 were enrolled.The structures of levator ani muscle observed with MRI during static breath holding and a maximal breath hold within 2 weeks before the operation and 1 year after the operation were collected and 3D image reconstruction of the pelvis and levator ani muscle was performed.The morphological changes in iliococcygeus，puborectal muscle and the attachment of the muscle to pubic symphysis were evaluated using the 2D model and those in the volume of the levator ani muscle，the levator ani muscle plate angle，levator hiatus width and length，and the distance between the pectineus muscle attaching to pubis and the inferior border of pubic symphysis were evaluated using the 3D model.Results　The following changes occurred postoperatively：（1）2D MRI images showed that the iliococcygeus changed to funnel shape in 11 cases（33.3% of the total），puborectal muscle changed to the shapes of “U”“O”or“irregular” in 10 cases（30.3% of the total）the attachment of the muscle to pubic symphysis changed to wave shape and defected shape in 19 cases（57.6% of the total）.（2）3D MRI images demonstrated that，the volume of the levator ani muscle decreased by 3.81 cm2；the levator ani muscle plate angle presented an increase of 4.13°；the distance between the pectineus muscle attaching to pubis and the inferior border of pubic symphysis exhibited an increase of 0.94 mm；levator hiatus width and length changed insignificantly.Conclusion　According to the postoperative changes in some parameters closely associated with the support function and morphology of levator ani muscle，we can infer that levator ani muscle's  power decreased postoperatively.It provides a theoretical basis for early clinical rehabilitation of pelvic floor.

Key words: Radical hysterectomy, Levator ani muscle, Three-dimensional reconstruction, Magnetic resonance imaging

摘要： 背景　已有报道显示广泛性子宫切除术后盆底支持结构改变与术后盆底功能障碍性疾病密切相关，但目前就术后盆底支持主要结构——肛提肌发生了何种改变尚无报道。目的　采用动态MRI及三维重建的方法观察广泛性子宫切除术前后肛提肌的形态变化特点，为临床了解术后盆底障碍性疾病（PFD）提供理论依据。方法　按照研究标准纳入2015年9月—2017年9月就诊于南方医科大学南方医院的ⅠA2~ⅡA2期宫颈鳞癌并行广泛性子宫切除术的患者33例，收集并对比其术前2周内和术后1年静态和最大屏气用力状态下MRI数据，三维重建出骨盆及肛提肌，利用二维MRI图像观察髂尾肌、耻骨直肠肌和肛提肌耻骨联合附着处形态的变化，利用三维模型检测肛提肌体积、肛提肌板角度、肛提肌裂孔横径和前后径、耻骨肌耻骨附着处距耻骨联合下缘距离。结果　术后11例（33.3%）髂尾肌发生“漏斗状”改变，10例（30.3%）耻骨直肠肌形态发生“U型”“O型”“不规则型”改变，19例（57.6%）肛提肌耻骨附着处发生“波浪形”和“缺损”改变。三维模型显示，术后肛提肌体积缩小了3.81 cm2，肛提肌板角度增大了4.13°，耻骨肌耻骨附着处距耻骨联合下缘距离增大0.94 mm，肛提肌裂孔横径、前后径无明显变化。结论　广泛性子宫切除术后部分与肛提肌支持力密切相关的形态和参数发生改变，术后肛提肌发生了趋向于盆底松弛改变的形态变化，可为临床早期盆底康复治疗提供理论依据。

关键词: 广泛性子宫切除术, 肛提肌, 三维重建, 磁共振成像