The Construction Of Placenta Digital Three-dimensional Model In The Body Of The Third Trimester Based On MRI Data And Its Application In Placenta Previa Cesarean Section

Placenta is to maintain the vital organs of the fetus in the womb of normal development, but also the role of various risk factors affect the fetus channel. As human placenta plan to carry out the study of the placenta and placental related diseases will rise to a new stage. Placenta structure is the basis of research, placental abnormalities not only seriously affect the proper functioning of the placenta, and harm to the smooth delivery of pregnant women. Placenta previa caused by abnormal position can cause pregnant women in late pregnancy bleeding and endanger the mother and child life , the emergency and severe case in Obstetric. Cesarean section is an important means of dealing with placenta previa and main mode of delivery . Placenta previa cesarean section often occurred hemorrhage, uterine incision selection inappropriate is one of the main reasons. In recent years a number of studies have shown that placenta previa cesarean section in placenta edge as the incision, try to stay away from the placenta can reduce intraoperative bleeding, so as to improve the prognosis of pregnant women and infants. But how to clear the placenta edge there is no good method. In recent years, as the rapid development of digital medical, the appearing of imaging-based digital three-dimensional technology for clinical diagnosis and treatment of diseases brought about new ideas. This study is the use of pregnant women in the third trimester MRI data to reconstruction body placenta digital three-dimensional model, clearing position edge of the placenta. Next, the uterine incision analog line established to guide intraoperative cesarean section determined in accordance with the preoperative analog line, thus avoiding the placenta, reduce blood loss. It is a new research foundation combined with clinical.With digital three-dimensional technology widely used in human studies, the imaging study of the placenta from in vitro to in vivo, from 2D to 3D. Three-dimensional ultrasound and MRI are the main imaging methods used in three-dimensional of clinical placenta imaging in vivo. Three-dimensional ultrasound examination is routine, so the preferred method of examination, but the small field of view, and the location of the placenta, fetal position, waiting for the doctor’s experience in ultrasound, the placenta is often difficult to be visualized the overall shape, so there is no use of ultrasound to build a three-dimensional model of the placenta. MRI as having no radiation, no damage, multi-planar imaging and soft tissue and high resolution imaging method, now that the MRI is safe to apply to pregnant women。 It is used in clinical MRI examination determine whether the location of the placenta and implanted there, using a two-dimensional image, to aid clinical diagnosis and treatment, but we can not visualize the overall shape of the placenta through the two-dimensional image. Currently digital three-dimensional reconstruction techniques based on MRI data has been applied in a number of clinical disciplines, but the application of a late start in obstetrics and more limited, very small for the three-dimensional reconstruction of the placenta in vivo MRI. This study based on the imaging sequence optimization, placenta MRI data is read, and the data import Mimics software placenta body constructed in digital three-dimensional model, as can be observed in the overall body shape and go placenta line more intuitive and accurate determine the location of the placenta edge to provide a new method.Placenta previa cesarean section often occurred hemorrhage, uterine incision selection inappropriate is one of the main reasons. The traditional incision will hurt the placenta, increased blood loss, increases the risk of placenta previa postpartum hemorrhage. Placenta varied shapes, the edges traveling is diverse, in order to avoid damage to the placenta caused by surgical incision, to avoid the placenta, select the cut edge of the placenta can be a good solution to this problem, but another problem is how to edge of the placenta positioning. Most researchers use ultrasound to clear intraoperative localization ,or put in hand to probe the placenta edge , However, these two methods are not in the case of visual observation of the placenta be integrally positioned placenta, placental edge thus determined not so accurate, yet at home and abroad to raise other methods to solve this problem. The present study, in vivo MRI placenta digital three-dimensional reconstruction model to determine the position of the edge of the placenta, in establishing the 3D perspective of the uterine incision analog line (M line), to seek more intuitive and accurate way to determine the uterine incision, to avoid injuring the placenta and reduce bleeding. Meanwhile, in order to explore the usefulness of the method, we also conducted a Clinical research, data confirmed that the method can reduce blood loss, with reliable clinical results.The study is divided into the following two partsPart OneThe study of the placenta digital three-dimensional model reconstruction for the third trimester in vivo based on MRI dataChapter OneThe study of the MRI imaging condition for placenta digital three-dimensional model[Objective]To study the MRI imaging scan sequence and scan parameters for the three-dimensional reconstruction of third trimester placenta in vivo.[Materials and Methods]1. Data collectionSelect 16 patients in our Hospital in 2014 January-June routine obstetric examination prompt placenta previa, with stable condition, no contraindications for MRI, voluntary line abdominal MRI, single live births, gestational age≥ 28 weeks cases of pregnant women.8 cases for scanning sequence selection, the remaining 8 cases to optimize scan parameters for analysis.2. The scanning deviceSignal Excite 3.0T superconductive MRI body scanners of American GE.3. Screening scanning sequence8 cases of pregnant women were randomly divided into 2 groups were selected two kinds of commonly used quick scan sequence is currently used for pregnant women, an MRI scan of the scans were compared, and finally select the placenta in vivo imaging clear, and conducive to the placenta three-dimensional imaging sequence.4. Optimization of scanning parametersFind the right sequence in the above experiment, based on the common scanning parameters selected sequence optimization, including repetition time(repetition time,TR),echo time(echo time, TE),thickness and spacing,field of view(field of view,FOV), excitation frequency(NEX),whether fat suppression, wherein when TR / TE settings selected 8 cases of pregnant women were divided into 4 groups, each using four different combinations of parameters for scanning,thereby performing a comparative study of the optimization of scanning parameters.[Result]1.The MRI imaging of different placenta MRI imaging sequences SSFSE-T2W1 was the ideal scanning sequeence to three-dimensional reconstruction from SSKE-TSWI single-shot fast spin-echo and FIESTA.2.The best scanning parameters of SSFSE-T2 WI SSFSE-T2WI sagittal thin scan with no fat saturation as an ideal scanning method is obtained, scan parameters are th fbllows sagittal TR 3000 ms,TE 120 ms,rsip angle 90 °, slice thickness 6 mm,the interlayer spacing 1 mm,rseld of vision(26-40)cm X(26-40) cm, matrix 256 x 224.[Conclusion]In this study, we found that SSFSE-T2WI sagittal thin scan with no fat saturation as an ideal scanning method. That does the groundwork for the placenta dighal three-dimcnsional model reconstmction of the third trimester in vivo based on MRI data.Chapthr Two The reconstruction of the placenta digital three-dimensional model thr the third trimesthr in vivo based on MRI dath[Objective]To explore the methods and sigrdficance of three-dimensional reconstruction of human placenta in the third trimester in vivo based on MRI scan data.[Materials and Methods]1. SubjectsTen woman in the third trimester with Placenta previa voluntary to take the examination in our hospital were recruited in the study. They are placenta previa selectd from2014 Nanfang hospital with stable condition, no MRI, contraindications, voluntary line abdominal MR], single live births, gestational age≥ 28 weeks.2. Get the MRI original dataUsing GE Signal Excite 3.0T superconductive MRI body scanners, for pregnant women row SSFSE-T2WI sagittal and axial thin scan with no fat saturation.Scanning range up to the bottom of the uterus, pelvic down to the lower edge of both sides including the entire uterus. Scanning parametersTR 3000 ms, TE 120 ms, flip angle 90°, sagittal slice thickness of 6 mm, axial as 4mm, the interlayer spacing 1mm, sagittal horizons (26-40)cm x (26-40)cm, matrix 256 x 224, axial field of view 35 cm× 35cm, matrix 320 x 224. All data is saved in Dicom 3.0 format.3.3-D reconstruction of placenta digital modelThe use of reconstruction software Mimics 10.01 for pregnant women all Dicom their original tomographic image is processed as follows(1) data entry and processing; (2) a three-dimensional reconstruction of the placenta; (3) Registration. Build a complete placental-uterine-Pelvis.[Result]1. Placenta digital three-dimensional model of 10 cases of pregnant women on MRI data were successfully reconstructed.2. Using the measurement tools (measure 3D Distance) measure related data the three-dimensional reconstruction model can help US understand the details.[Conclusion]In-vivo Placenta can be reconstructed into three-dimensional model based on MRI data set,which has advantage of large visual field and can be observed in various directions. It provides a new method for the study of placenta in vivo, which has exthnsive application foreground.Part Two The application of the third trimester placenta in vivo MRI reconstruction model in placenta previa cesarean section Chapter One To establish analog line of placenta previa preoperative uterine incision with MRI 3 d reconstruction model[Objective]The use of in vivo MRI placenta digital reconstruction technique to determine the specific location of the edge of the previa patients’ placenta, and to explore methods of preoperative ulterine incision analog line(M line) established and its significance.[Materials and Methods]1. Data collectionSelect 45 cases of pregnant women due to placenta previa cesarean section for the study period from January 2014 to January 2016 in our hospital- Inclusion criteria;① single live births, gestational age ≥28 weeks; ② prenatal imaging examinations showed placenta previa. ③ pregnant women without contraindications to MRI, and voluntarily imderwent MRI; ④ one week before childbirth expert MRI. 45 cases of pregnant women,average age of(31.62 ± 3.84) years,mean gestational age(35.59 ±3.23) weeks.2. Get the original MRI dataThe same with the chapter one.3. Construction of 3-D digital model of placentaThe use of reconstruction software Mimics 10.01 for pregnant women all Dicom their original tomographic image is processed as follows(1) data entry and processing; (2) a three-dimensional reconstruction of the placenta; (3) Registration. Build a complete placental-uterine-Pelvis.4. To determine the edge of the placenta① measure the distance from the edge of the placenta cervix to determine the type of placenta previa; ② to the edge of the pubic bone to do a horizontal line from the edge of the placenta to measure this line to determine the specific location on the edge of the placenta.[Result]1. Basic TypingMRI image data of 45 cases of pregnant women is clear, in line with the placenta in vivo three-dimensional reconstruction requirements.45 cases of pregnant women complete placenta previa in 26 cases,8 cases of partial placenta previa, marginal placenta previa in 10 cases, low-set placenta in 1 case.2. placenta previa typing in details45 cases of pregnant women,39 cases of pregnant women placental involving the anterior wall of the uterus, according to the three-dimensional reconstruction of the measuring data, type the following ①Ⅰ (7/39)involving the anterior wall of the uterus are part of the placenta attached to the lower uterine segment, this part of the placenta the upper edge of the lower uterine segment below the ceiling (distance cervix 70mm) (as shown in 2-1-1a); ②Ⅱ(10/39)involving the anterior wall of the left or right front wall of the uterus, placenta edge over the front wall the lower limit only locate the placenta, visualize the relative positional relationship between the placenta and uterus, set specific quantitative measure more accurately determine the edge of the placenta, help us know placental’ localization.of the uterus, below the umbilicus(Figure 2-1-1b);③III(19/39): n involving the anterior wall of the uterus, placenta onthe front wall of the upper section,the lower edge of the plane over the umbilical ulterine uthrus(Figure 2-1-1c);④IV(3/09)involving the majority of the front wall of the uthrus, placenta edge over tiie umbilical plane(Figure 2-1-1d). The remaining 6 cases not involving the placenta of pregnant women anterior uterine wall, the rear wall of the placenta, but the placenta covers a portion of the cervix or near the edge of the cervix.3 uterine incision analog line(M line) is dethrmined3. To determine the lUerine incision analog line(M line)Not involving the aiterior wall of the uterus,placera previa lower uterine segment transverse incision, that upper limit(peritoneum) lower uterine segment at2-3cm; involving the anterior wall of the uterus to establish the placenta previa,uterine incision simulate different lines for different types( M line),① I type :placenta on the front wall portion does not exceed the margin of the lower uterine segment, choose Select lower uterine segment transverse incision,preoperative identified as M line(as shown 2-1-2);② II type determining tihe three-dimensional model in the placenta the rear edge,in the absence of the placenta covers the walls of the palace determine u1erine incision M line(as shown 2-1-3);③ Ⅲ type; determining edge of the placenta in the tluee-dimensional model thdetermine the upper edge of the li n e move 2cm the n,determined to M line(as shown2-1-4); ④IV type：three-dimensional model of the placenta were determined after covering the front wall,measuring the thickness of practicable placenta,placenta positioned relatively thin region, the establishment of the uterine incision analog line M line(as shown 2-1-5). M line length depend on the particular circumstances.[Conclusion]The accuracy of preoperative body MRI three-dimensional reconstruction can notChapter TwoThe application of the uterine incision analog line (M line) on placenta three-dimensional model based on MRI data in placenta previa Cesarean Section[Objective]The use of MRI to determine the precursor placenta digital three-dimensional reconstruction surgery placenta previa cesarean section uterine incision analog line (M line), applied to the placenta previa cesarean section, and analyze its effects.[Materials and Methods]1. Data collectionSelect 45 cases of pregnant women due to placenta previa cesarean section for the study period from January 2014 to January 2016 in our hospital. Inclusion criteria ① single live births, gestational age≥28 weeks;② prenatal imaging examinations showed placenta previa. ③ no contraindications to MRI, and voluntarily underwent MRI;④ one week before childbirth expert MRI. This 45 cases of pregnant women as the observation group, and the remaining 89 cases as the control group.2. Get the original MRI dataThe same with the chapter one of the part two3. Construction of 3-D digital model of placentaThe same with the chapter one of the part two4. Determine the observation of uterine incision analog line (M line)The same with the chapter one of the part two5. Surgical methods5.1 abdominal incisionVentral midline abdominal incision is usually in the upper abdomen or longitudinal incision around the navel. Determine the specific location of the placenta through the three-dimensional model after model Measure the distance from the edge of the placenta and pubic horizontal line, and then not open before use custom sterilization foot horizontal line as a reference to pubic vertical measurement, if the distance exceeds ① distance not more than the selection of a common abdominal incision;② umbilical plane, then choose extended incision around the navel.5.2 Uterine incision① observation groupthe use of MRI to determine the model of the digital three-dimensional reconstruction of the M line, identified by incision during surgery, gradually cut the myometrium on both sides with tissue forceps clamp incision to expose the fetal membranes. ② control groupLearn by ultrasound placenta and uterus and uterine position substantially opposite the mouth, no clear positioning, and more have been lower uterine segment transverse incision or vertical incision myometrium, lift margins, childbirth fetus.5.3 Hemostatic processMore than the amount of bleeding can take the following methods to stop bleeding(1) Carbetocin card prostaglandin tromethamine and other uterotonics; (2) the uterine B-Lynch suture; (3) on both sides of the lower uterine segment by a broad ligament avascular zone beam tourniquet; to be "8" or "mouth" suture (4) uterine bleeding at the placental attachment surface; (5) the balloon yarn block hemostasis; (6) internal iliac artery ligation. When the various measures to stop bleeding ineffective hysterectomy. Surgeries were performed by qualified and experienced gynecologist performed.6. Observationsblood loss, transfusion rate, operative time, hysterectomy rate, postoperative hospital stay, Apgar score.7. Statistical MethodsUsing SPSS 20.0 statistical software, measurement data (age, blood loss, operative time, Apgar score, etc.) with the mean ± standard deviation (± s) that count data (for transfusion, hysterectomy rates, etc.) expressed as a percentage (%). Measurement data using t test or analysis of variance, count data using chi-square test.[Result]1.45 patients (study group), the mean age was (31.62 ± 3.84) years, mean gestational age (35.59 ± 3.23) weeks; 89 pregnant women (control group), the mean age was (30.86± 5.41) years, mean gestational age (35.94± 2.87) weeks. Two groups of maternal age, BMI, gestational age, history of previous cesarean section, percentage complete placenta previa, placenta accreta percentage, the percentage of emergency cesarean section, compared with the preoperative hemoglobin level was not statistically significant (P> 0.05).2. Study group and the control group of pregnant women blood loss were (678.65 ± 649.54) ml, (933.96 ± 695.25) ml, operation time was (65.13 ± 27.38) min, (86.88 ± 54.43) min, transfusion rates were 24.45%(11/45),42.69%(38/89) differences were statistically significant (P<0.05). The two groups of pregnant women, postpartum hemorrhage≥ 1000ml 24h percent hysterectomy rate, mortality, Apgar score<7 percent compared with no significant difference (all P> 0.05).[Conclusion]The use of in vivo MRI data were reconstructed to determine placenta previa cesarean section incision edge of the placenta, and can effectively avoid the placenta, reducing blood loss, shorter operative time, reduce neonatal asphyxia rate, improve maternal-fetal prognosis.