3D Visualization Of Female Pelvic Floor Structure

Background and ObjectivePrecision medicine is based on individualized medical treatment,combining with the living environment and clinical data,to accurately diagnose disease,thus to develop personalized disease prevention and treatment plan.Currently,study on precise medicine in gynecological surgery is not available yet.Female pelvic floor has complicated 3D anatomy and deep anatomical location in the pelvis.However,it is very important that affects the success rate of the operation and postoperative complications in many gynecological surgery,especially in cervical cancer(CC)and pelvic organ prolapse(POP).CC is the most common gynecological cancer and radical hysterectomy(RH)is the principal treatment for early CC.Intraoperative complications such as bleeding and injuries of urinary bladder,rectum,ureter,and postoperative complications such as defecation and urination dysfunction are hard to avoid completely.An important reason is that the anatomic structure of pelvic floor is deep and its adjacent structures around the cervix are complex.Moreover,the three-dimensional structure and its adjacent relationship of the cardinal ligament(CL),uterosacral ligament(USL),vesicocervical ligament(VCL)and pericervical ring(CR)have not been fully understood yet,which is still controversy and affect the operative efficacy of extensive hysterectomy and comprehensive follow-up treatment of cervical cancer.Female pelvic floor functional disorder(PFD)refers to disease caused by the relaxation of pelvic support tissue,including stress urinary incontinence(SUI)and POP.As the population aging,the incidence of pelvic floor functional disorder increases year by year,which seriously affects middle-aged and old women’s physical and mental health and life quality.In severe cases of PFD,patients need surgery,but the complications and postoperative recurrence rate of traditional surgery was still high,due to the inaccuracy information of the degree of pelvic organ prolapse and the position the dysfunction structure of the complex pelvic floor.With the development of the pelvic floor reconstruction,accurate preoperative assessment of anatomical relationship of pelvic organ and the adjacent structures,the degree of prolapse and the accurate position of the disfunction structure become the premise of comprehensive measures of diagnosis and treatment and effective individualized treatment.Therefore,more detailed anatomic knowledge of pelvic floor is needed.In the past,the study of female pelvic floor mainly relies on the autopsy.In recent years,many scholars put forward different methods to study the anatomic structure of pelvic floor,in order to strengthen the understanding of its anatomy.Currently,research on three-dimensional(3D)visualization of pelvic anatomy has been more and more taken seriously.However,the previous anatomic study of pelvic floor is not detailed and accurate enough,for it was based on …,autopsy that has certain limitations: large tissue damage,poor repeatability and spatial visualizatiosn.magnetic resonance imaging(MRI)and Computed tomography(CT)are based on imaging studies and not accurate enough to identify the precise structure characteristics,so they can’t really present female pelvic anatomic structures.Hence,new methods to improve the study of female pelvic anatomy are needed on the basis of optimized indicators of the previous study.MRI,with high resolution for soft tissue,can scan pelvic floor from multiple dimension.It has been increasingly applied in the study of the structure of the pelvic floor and the diagnosis of POP.Without radiation,MRI is non-invasive examination,with characteristics like high resolution of soft tissue,dynamic and static function and multiple plane imaging.It can present pelvic organ prolapse and pelvic floor for comprehensive evaluation,providing a preferable method to study pelvic anatomy.However,the image of MRI is gray-scale and the anatomical structure is relatively difficult to identify in detail,especially the indistinct boundary of soft tissue.Furthermore,factors like posture,respiratory and intestinal peristalsis could affect the quality of two-dimensional scanning image.Thus,it cannot present the real and accurate anatomic structure of female pelvic floor and its relationship with adjacent organs.Chinese visible human(CVH)data sets,with true color,high resolution,small image deformation,thin thickness and high image registration,has a broad application prospect in many fields,with the development of digital medicine.Combining with MRI image data,CVH is expected to become a new approach to study the anatomic structure of female pelvic floor,to realize visualization of female pelvic floor,and to guide various gynecologic surgery.This study employed the pelvic data set of CVH,combining thin-sectional healthy female pelvic MRI images and operation pictures from Laparoscopic Radical Hysterectomy(LRH),and to reconstruct a 3D model of pericervical structure with its subdivision that provides forceful morphological basis for imaging diagnosis and simulation teaching for LRH and pelvic floor reconstruction surgery.At the same time,we built a 3D visualized model of POP pelvic floor based on the sagittal MRI images of uterine prolapse patients,to discuss its image features and its significance for clinical diagnosis,to achieve the precise study of female pelvic floor,to lay the foundation of precise diagnosis and treatment of gynecological disease.Methods1.Three CVH female data set were studied.All cadavers were enrolled in the body donation program of the Chinese Visible Human(CVH)project.The cross-section images from the iliac crest to the lower rim of the perineum were selected from CVH2,CVH4 and CVH5.pelvic organs and its adjacent structures including uterus body,cervix,vagina,bladder,rectum,ureter,VCL,USL,CL,CR,PVS,PRS,pelvic vessels,mesorectum,piriformis,coccygeal muscles,levator ani muscle,sacrospinous ligament,pelvic bones,sacrum,coccyx and anterior sacral fascia were segmented and three-dimensional digital model were created.At the same time,three pelvic MRI images of healthy nulliparous female volunteers were selected for thin-sectional scanning.Images under laparoscope in Radical hysterectomy were kept and do comparative work with CVH and MRI images.2.30 patients with uterine prolapse were chosen as experiment group and 20 cases of healthy women were chosed as control group in September 2013 to June 2013,MRI was performed on relaxation and Valsalva maneuver with two groups.Using Amira commercial software,We analyzed the MRI images and created 3D model.3.Statistical analysis: SPSS 19.0 statistical analysis software were employed for data processing,± for standard deviation in measurement data,paired t test and independent sample t-test for normal distribution of data.When P < 0.05,it has statistical significance.Results:1.We 3D reconstructed bony pelvis and its adjacent structures including vesicocervical ligament,uterosacral ligament,cardinal ligament,pericervical ring,pelvic vessels,mesorectum,paravesical space and pararectal space with Amira software,presenting pericervical structures and their spatial relationship.2.We quantified and segmented the length,width,thickness of organs like vesicocervical ligament,uterosacral ligament,cardinal ligament,pericervical ring on the basis of the 3D model.3.We created 3D models of the prolapse group and the control group and measured parameters,such as line PCL,angle G1,angleG2,line H,line M,cervical length,line C,line B.4.3D models of two groups of pelvic floor structures were successfully established,two phase were compared between groups: there was no significant difference in PCL,H line,G1 angle,G2 angle,cervical length(P>0.05),and had significant difference in M lines,C lines(P<0.05);there was no significant difference during relaxation(P>0.05)and had significant difference during Valsalva maneuver between two group(P<0.05)in B line;difference value were compared between relaxation and Valsava maneuver within one group :there was no significant differences in PCL(P>0.05),but there was great significant in M line,G1 angle,G2 angle,B line,C line in two groups(P<0.05);there was significant difference in H line in control group(P<0.05)and no significant difference in M line in prolapse group(P>0.05).Conclusion:1.Combining the accurate data set of CVH,and thin-sectional healthy female pelvic MRI images with operation pictures from a RH,we reconstructed female pelvis,pelvic organs,pericervical structures,retroperitoneal space and pelvic vessels and nerves,and created a 3D visualized female pelvic model.2.On the basis of the 3D model,we quantified and segmented the length,width,thickness of vesicocervical ligament,uterosacral ligament,cardinal ligament,pericervical ring etc.,which provides significant guidance for the diagnosis and treatment of CC and POP.3.MRI TES T2WI sequences can clearly show the pelvic structure and the accuracy of the measurement,a applicable way of diagnosis and treatment for POP.4.The 3D model,presenting the relationship of the structures,is helpful for the location of the dysfunctional part and a good method for surgery simulation,providing support for anatomy teaching and study of mechanics of pelvis.