The Clinical Study Of Pelvic Imaging Measurements To Evaluate The Occurrence Of LARS After Different Anal Preservation Operations For Low Rectal Cancer

Objective Through the dynamic Pelvic MRI and 3DHR-ARM examination techniques,the correlation between pelvic morphology,anal dynamics and pelvic diameters of patients with low rectal cancer undergoing different anal preservation operations and postoperative dynamic pelvic MRI and 3DHR-ARM indexes was quantitatively analyzed.The clinical value of pelvic imaging measurements in the evaluation of LARS after different anal preservation operations in low rectal cancer was discussed.Materials and methods A total of 78 patients with low rectal cancer diagnosed by anorectal department of Tianjin Union Medical Center were enrolled in this study.All the patients underwent rectal touch,colonoscopy,pelvic dynamic MRI,3DHR-ARM and other examinations before surgery,and received surgical treatment within one week after the examination.All the pelvic diameters were measured at the imaging workstation.38 patients who underwent laparoscopic anal preservation combined with prophylactic ileostomy were included in the laparoscopic group,40 patients who underwent laparotomy combined with prophylactic ileostomy were included in the laparotomy group.All the patients underwent pelvic dynamic MRI and 3DHR-ARM examination again and filled in the Chinese version of LARS score questionnaire three month after surgery.SPSS24.0 statistical software was used to analyze the relationship between the pelvic dimension of the laparoscopic group and the laparotomy group of the occurrence of LARS,so as to find the pelvic diameters that could affect the occurrence of LARS in the laparoscopic group or the laparotomy group.Independent sample T test was used to compare the indexes of postoperative pelvic dynamic MRI or 3DHR-ARM of the laparoscopic group and the laparotomy group.Pearson correlation analysis was used to analyze the correlation between pelvic dimensions with pelvic dynamic MRI or 3DHR-ARM examination indexes,so as to explore the specific reasons that pelvic diameter affected the occurrence of LARS under different surgical methods.Results(1)The sacrococcygeal distance and the sacrococcygeal winding distance will affect the occurrence of LARS in the laparoscopic group,that is the length of sacrococcygeal distance and the sacrococcygeal winding distance are the risk factors for the occurrence of LARS.The interspinous distance,the sacrococcygeal distance and the sacrococcygeal winding distance will affect the postoperative occurrence of LARS in the laparotomy group,that is the length of interspinous distance 、 sacrococcygeal distance and sacrococcygeal winding distance are the risk factors for the occurrence of LARS.(2)The length of H line and M line in the laparoscopic group was shorter than that in the laparotomy group(P<0.05),The postoperative rectal pressure,initial sensation threshold and initial defecation threshold of the laparoscopic group were closer to normal than those of the laparotomy group(P<0.05).(3)The correlation between pelvic dimension and postoperative dynamic MRI indexes in the laparoscopic group were as follows: the sacrococcygeal distance was negatively correlated with the puborectalis muscle in lifting phase(r=-0.380,p=0.019).The sacrococcygeal distance and the sacrococcygeal winding distance were positively correlated with the M line in defecating phase(r=0.454,p=0.004),(r=0.334,p=0.041).The correlation between pelvic dimension and postoperative dynamic MRI indexes in the laparotomy group were as follows: In resting phase,the interspinous distance and the intertuberous distance were negatively correlated with the length of H-line(r=-0.348,p=0.028)、(r=-0.445,p=0.004),the interspinous distance and the intertuberous distance were positively correlated with the thickness of the puborectalis muscle(r=0.440,p=0.004)、(r=0.373,p=0.018).In lifting phase,the interspinous distance was negatively correlated with the H-line length(r=-0.362,p=0.022),the sacrococcygeal distance and sacrococcygeal winding distance were positively correlated with the H-line length(r=0.453,p=0.003),(r=0.476,p=0.002),the interspinous distance was positively correlated with the thickness of the puborectalis muscle(r=0.353,p=0.025).In defecating phase,the interspinous distance was negatively correlated with the H-line(r=-0.340,p=0.032),the sacrococcygeal distance and sacrococcygeal winding distance were positively correlated with the length of the H-line(r=0.426,p=0.006)、(r=0.312,p=0.049)and were positively correlated with the length of the M-line(r=0.533,p=0.000),(r=0.475,p=0.002),the intertuberous distance was positively correlated with the thickness of the puborectalis muscle(r=0.350,p=0.027).(4)The correlation between pelvic dimension and postoperative 3DHR-ARM indexes in the laparoscopic group were as follows: The interspinous distance was positively correlated with the maximum anal systolic pressure(MSP)(r=0.464,p=0.004),the sacrococcygeal distance and sacrococcygeal winding distance were negatively correlated with the initial sensory threshold(IST)(r=-0.404,p=0.012),(r=-0.446,p=0.005).The correlation between pelvic dimension and postoperative 3DHR-ARM indexes in the laparotomy group were as follows: anteroposterior distance of the pelvic inlet and the interspinous distance was positively correlated with MSP(r=0.337,p=0.033)、(r=0.418,p=0.007),the interspinous distance was positively correlated with initial defecate threshold(IDT)(r=0.560,p=0.000),the sacrococcygeal distance and sacrococcygeal winding distance were negatively correlated with the IDT(r=-0.791,p=0.000)、(r=-0.610,p=0.000).Conclusion(1)Pelvic dimension will affect the occurrence of LARS after anal preservation for low rectal cancer.The length of sacrococcygeal distance and sacrococcygeal winding distance are the independent risk factors for LARS after laparoscopic surgery,the length of intertuberous distance、 sacrococcygeal distance and sacrococcygeal winding distance are the independent risk factors for the LARS after the laparotomy.(2)The rate of postoperative LARS in the laparoscopic group was lower than that in the laparotomy group.Pelvic floor relaxation in the laparotomy group was more serious and postoperative rectal pressure recovery was slower.The IST and IDT of patients in the laparoscopic group were higher than those in the laparotomy group,indicating that the pelvic floor nerve injury in the laparoscopic group was less than that in the laparotomy group.(3)Patients with a deep pelvis are prone to combine LARS after laparoscopic surgery,Patients with a deep pelvis or narrow pelvis are prone to combine LARS after the laparotomy,the main reason is puborectalis muscle and pelvic floor nerve plexus injuries during the operation.