MRI Study On Morphology And Function Of The Levator Ani Muscle In Normal And Stress Urinary Incontinence Women

Methods Totally 65 healthy women(healthy group)who were divided into cesarean section group and spontaneous delivery group according to the mode of delivery and nulliparous healthy women(nulliparous group)and 12 SUI femail(SUI group)underwent MRI in both natural and increased abdominal pressure states.Using the uMR 1.5T superconducting MR system,the abdominal 6 channel phased array coil.Scanning sequence:MRI coronal and sagittal fast spin echoes T2WI:TR4300-4600 ms,TE 70-80 ms,thickness 4 mm,inter factor 0.8 mm,FOV 200 mm*280 mm,flip angle 150 ~o;transverse fast spin echo T1WI:TR 450 ms,TE 10 ms,thickness 3 mm,inter factor 0.6 mm,FOV 260 mm*280 mm,turning angle 120~o;transverse fast spin echo T2WI:TR 4200 ms,TE 80 ms,thickness 3 mm,inter factor0.6 mm,FOV 260 mm*280 mm,flip angle 150~o.After the increase of abdominal pressure,the MRI scan was performed by axial,sagittal and coronal banlanced steady state free precession T2WI.MRI coronal,sagittal and transverse T2WI:TR 5.7-6.5 ms,TE 2.8-3.2 ms,thickness 4 mm,inter factor 0.8 mm,FOV 200 mm*280 mm,flip angle 75 ~o.To measureICM、cICA、sICA、PRM、LHL、LHW、LHA,then compare the differences between the two groups and the difference between P<0.05 was statistically significantResults1、ICMNatural state,there were significant differences in ICM between SUI group and healthy group,p=0.025,0.029;there were significant differences between SUI group right ICM and cesarean section group、spontaneous delivery group p=0.041,0.013,and left ICM were p=0.045,0.018.Increased abdominal pressure state,there were significant difference in ICM between SUI group and healthy group,p=0.014,0.002;SUI group right ICM compared with cesarean section group、spontaneous delivery group and nulliparous group right ICM p=0.072,0.010,0.035.The left ICM p values were 0.016,0.001,0.023.2、ICANatural state.There were significant difference in right and average cICA between the nulliparous group and the fertile group,p=0.010,0.006.There were significant differences in two side and average cICA between SUI group and healthy group,p=0.010,p=0.005 and p<0.001.There were significant differences in two side and average sICA between SUI group and healthy group,p=0.020,p=0.040 and p=0.002.SUI group right cICA compared with cesarean section group、spontaneous delivery group and nulliparous group were p=0.008,0.032,0.019,left cICA p=0.004,0.006,0.044,right sICA p=0.044,0.283,<0.001,left sICA p=0.033,0.362,0.012.Increased abdominal pressure state,There were significant differences in two side and average sICA between the nulliparous group and the fertile group,p<0.001,0.016,<0.001.There were significant difference in average sICA on both sides between SUI group and healthy group,p=0.005,0.041.SUI group right sICA compared with cesarean section group、spontaneous delivery group and nulliparous groupwere p=0.026,0.089,<0.001,left sICA p=0.092,0.266,0.001.3 PRMNatural state,there were significantly differenc in both sides of PRM between SUI group and healthy group,p=0.020,0.005.SUI group right PRM compared with cesarean section group、spontaneous delivery group and nulliparous group were p=0.013,0.047,0.058,and the left PRM were p=0.006,0.013,0.015.Increased abdominal pressure,There were significant difference in left PRM between SUI group and healthy group p=0.037.SUI group right PRM compared with cesarean section group、spontaneous delivery group and nulliparous group were p=0.202,0.135,0.049,and the left PRM were p=0.018,0.096,0.047.4 LHL、LHW、LHANatural state,There were significant difference in LHL between the between the cesarean section group and the natural delivery group,p=0.040.Increasing abdominal pressure state,SUI group LHW、LHA compared with nulliparous group were p=0.016,0.033.Conclusion(1)MRI can accurately evaluate morphological and functional changes of ani levator muscle in females.(2)Pregnancy and spontaneous delivery can lead to the right posterior iliococcygeal muscle relaxation and diminished posterior contractile function.There was no significant difference between the spontaneous delivery women and the cesarean section women in the levator ani muscle function,and levator hiatus was elongated.(3)The occurrence of SUI is closely related to the relaxation of the outer and lower part of the iliococcygeal muscle,the weakening of the posterior and lower part of the iliococcygeal muscle,and also to the weakening of the puborectal muscle.