动态MRI成像技术对低位直肠癌保肛术后LARS的评估价值

The evaluation value of dynamic MRI imaging technology for LARS after anorectal preservation surgery in low rectal cancer

目的 探讨动态MRI成像技术在评估低位直肠癌保肛术后低位前切除综合征(LARS)形态学及动力学变化中的研究价值。方法 前瞻性收集35例低位直肠癌保肛手术后出现LARS的患者。受试者均于术前1周和术后3个月内行盆腔常规MRI及动态MRI检查,将常规MRI检查作为静息相,动态MRI检查获得提肛相和力排相,于3时相上测量肛直角(ARA)、耻骨联合下缘到耻骨直肠肌直肠后壁附着点连线长度(H线)、耻骨直肠肌直肠后壁附着点到耻尾线垂直长度(M线)、耻骨直肠肌厚度、肛门内括约肌和外括约肌厚度等参数,比较患者术前与术后、中度与重度间MRI各参数的差异。结果 LARS患者术前和术后的ARA、H线长度、M线长度在提肛相最小、力排相最大、静息相居中,术前的耻骨直肠肌和肛门内、外括约肌厚度在提肛相最大、力排相最小、静息相居中,3时相间差异均有统计学意义(P<0.05);而术后的耻骨直肠肌和肛门内、外括约肌厚度的3时相间差异无统计学意义(P>0.05)。LARS患者术后的ARA均大于术前,耻骨直肠肌厚度、肛门内括约肌厚度(静息相和提肛相)、肛门外括约肌厚度均小于术前,差异有统计学意义(P<0.05)。重度LARS患者术后静息相和提肛相上的ARA大于轻度患者,术后静息相上的肛门内括约肌厚度小于轻度患者(P<0.05),其余指标间差异无统计学意义(P>0.05)。结论 动态MRI检查技术将动态图像与定量指标相结合,可作为评估LARS的重要依据。

Objective To explore the value of dynamic MRI imaging in investigate the morphologic and dynamic factors of low anterior resection syndrome(LARS)after anal preservation surgery in patients with low rectal cancer.Methods Thirty-five patients who developed LARS after anal preservation surgery for low rectal cancer were prospectively collected.Subjects were underwent routine MRI and dynamic MRI of pelvis 1 week before and 3 months after surgery respectively.Routine MRI was used as the resting phase,and dynamic MRI was used to obtain the rapture phase and forceful phase.Parameters such as anal rectus angle(ARA),the length of the line connecting lower edge of pubic symphysis to the posterior wall attachment point of puborectal muscle(H-line),the vertical length from posterior wall attachment point of puborectal muscle to pubococcygeal line(M-line),thickness of puborectal muscle,and thickness of internal and external anal sphincter were measured at the three time phases.The differences between preoperative and postoperative,and moderate and severe LARS patients were compared by measuring relevant indicators.Results The preoperative and postoperative ARA,H-line length and M-line length of LARS patients were the smallest in the rapture phase,the largest in the forceful phase,and the middle in the resting phase.The postoperative thickness of puborectalis muscle and internal and external anal sphincter were the largest in the rapture phase,the smallest in the forceful phase,and the middle in the resting phase.There were significant differences between the three phases(P<0.05).There were no significant differences between the three phases of postoperative puborectalis muscle thickness and internal and external sphincter thickness(P>0.05).The postoperative ARA was greater than preoperative ARA in LARS patients,and the thickness of puborectalis muscle,the internal anal sphincter(resting phase and rapture phase),and the external anal sphincter were smaller than preoperative ARA,and the differences were statistically significant(P<0.05).The ARA in resting phase and rapture phase was greater in patients with severe LARS than that of patients with mild LARS,and the thickness of internal anal sphincter in resting phase was less in patients with severe LARS than that of patients with mild LARS (P<0.05). However, the differences between the other indicators were not statistically significant (P>0.05). Conclusion Dynamic MRI examination technology combines dynamic images with quantitative indicators can be used as an important evaluation basis for LARS patients.