| During pregnancy,a series of endocrine and anatomical changes have taken place in women.These changes have different degrees of physiological and even pathological changes on the whole body.Among them,the dysfunction of pubic symphysis（PSD）is a common skeletal muscle dysfunction,which seriously affects the quality of life in pregnant and postpartum women.The main clinical manifestation of PSD is severe pain in the pubic symphysis,which can radiate to the perineum,groin,back and thigh area.The symptoms worsen when walking,unilateral weight-bearing or hip abduction,and the performance is rocking gait.Symptoms usually begin in the latter half of the pregnancy period,ranging from mild to severe,with an incidence rate of about 57.2%.During pregnancy,due to the influence of hormones known as relaxation hormone（widely considered as the main cause of PSD）,the elasticity of tendons,ligaments and muscles in pregnant women increased,the distance between the pubic symphysis was enlargement,the pelvis joint relaxed and the cartilage between pubis stretched.When the changes of ligament and cartilage exceed the physiological limit,the pregnant women will suffer from pain in pubic symphysis.PSD can occur alone or with sacroiliac joint dysfunction.The incidence rate of PSD in primipara,early pregnancy,middle and late stages is 74%,12%,34%and 52%respectively.Most of the pain subsided in 1-6 months after the birth,25%of women still suffered pain in 4 months after the postpartum,and a few 12 months later were still accompanied by pain,which seriously affected the physical and mental health of pregnant women.PSD is usually treated conservatively（bed rest and pelvic abdominal belt）and physical therapy（gradual exercise,stretching exercises,muscle strength stability exercise of waist and pelvis）can be adopted according to individual differences.Complete bed rest can effectively reduce pain in the early stage of the disease,but physical therapy is not suitable for the patients with PSD in pregnancy.Therefore,early detection and intervention can effectively improve the quality of life in PSD patients.At present,the main examination method of pubic symphysis in pregnancy is ultrasound（US）,but US depends on the experience of the operator and can only observe part of the joints,which shows limited changes of PSD related structure during pregnancy.Magnetic resonance imaging（MRI）can effectively compensate for the shortcomings of ultrasound examination,and it is more advantageous in displaying soft tissue injury（especially pubic ligament complex）and osteoedema under cartilage.But it is difficult to diagnose early articular cartilage injury,only through morphological changes and joint gap changes to evaluate the serious articular cartilage injury.The emerging quantitative MRI technology of cartilage can provide information on the ultrastructure and biochemical components of cartilage and quantitatively evaluate the degree of cartilage injury,including measurement of relaxation time（T2,T2*and Tip imaging）,delayed gadolinium enhanced MRI of cartilage（dGEMRIC）,ultra short echo time（UTE）,diffusion tensor imaging（DTI）,The chemical exchange saturation transfer（CEST）imaging of glycosaminoglycan（GAG）,Sodium imaging etc was studied.Among them,The T2 relaxation time analysis has been applied to the determination of the pubic joint cartilage in adults,and the magnetic resonance gradient echo volume internal examination（MR-VIBE）has been applied to the diagnosis of epiphyseal in the pubic process（traction）in adolescents.In the late pregnancy,the image quality is easily affected by fetal movement and maternal air holding problems,while the volume internal breath hold examination,StarVIBE)is a T1 weighted 3D gradient echo sequence,which is less affected by motion displacement,and pregnant women can scan in free breathing state;T2*mapping sequence is based on the rapid gradient echo imaging of small turning angle,which has short imaging time,high spatial resolution,no need for contrast agent or special software and hardware processing,and can provide space macromolecular structure and information related to interaction with water molecules.Through the determination Quantitative parameters have been widely used in the study of cartilage of ear,knee,sacroiliac joint,hip joint,lumbar joint and so on.At present,the study of pubic joint cartilage and ligament in pregnancy is still in its infancy.There are few reports in the literature.This study is aimed at applying MRI in combination with the current research status T1-StarVIBE and T2*mapping sequences were used to quantitatively analyze pubic symphysis distance,thickness of pubic anterior ligament and changes of pubic cartilage.The potential causes of pain in pubic symphysis area was explored,which lay the foundation for the best period and mode of PSD diagnosis,treatment ’and prompt preventive measures in clinical work to reduce incidence rate.There are three parts in the study:Part 1.To observe the distance between pubic symphysis and the thickness of anterior pubic ligament in pregnant women with T1-StarVIBE SequenceBackground and purpose:T1-StarVIBE is a three-dimensional gradient echo sequence,which can effectively reduce the motion displacement sensitivity,The purpose of this study was to investigate the feasibility of T1-StarVIBE sequence in evaluating the pubic symphysis of primipara in late pregnancy and postpartum,and to observe the variation of the distance between the pubic symphysis and the thickness of the anterior pubic ligament,so as to provide reference for clinical application of MRI in evaluating the pubic symphysis in late pregnancy To provide a reference standard for the abnormal changes of osseointegration.Materials and methods:This study was approved by the ethics committee of our hospital.Fifty seven primiparas（mean age 26.3 years,mean gestational age 32.2 weeks）in late pregnancy（28-42 weeks）and 62 women（mean age 25.6 years）in full-term postpartum（42 cases in natural delivery group and 20 cases in cesarean section group）in group A and 62 non pregnant women（mean age 25.2 years）in group C were examined by Pelvic MRI as the reference control group from January to December during 2016 in Medical Imaging Department of Shandong Provincial Hospital.The inclusion criteria were as follows:（1）no history of pelvic deformity and trauma;（2）Shameless bone combined with pain symptoms;（3）The gestational weeks of healthy primiparas ranged from 28 weeks to 42 weeks;The primipara in the third trimester of pregnancy and the female at 42 days postpartum were singleton pregnancy.Subjects who could not tolerate MRI due to claustrophobia or other reasons were excluded;MRI data with artifacts were discarded.All subjects underwent axial VIBE and T1-StarVIBE sequences of pubic symphysis with 1.5T MRI.The collected images were transferred to Siemens workstation,and two doctors with more than 10 years of experience in bone and joint MRI diagnosis scored the degree of motion artifacts in T1-VIBE and T1-StarVIBE sequence images and the display clarity of pubic symphysis articular cartilage and ligament by double-blind method:（1）unclear display（structure can not be distinguished,motion artifacts are large,affecting the observation）,scored 1 point;（2）visible,2 points were scored for fuzzy（structure can be distinguished,but fine structure can not be displayed,with motion artifact）;3 points were scored for clear（structure can be distinguished,fine structure can be distinguished,without obvious motion artifact）.On the T1-StarVIBE sequence,MRI images were selected to show the middle plane between the uppermost surface and the lowermost surface of the superior pubic branch,and the average width of pubic symphysis and the thickness of anterior pubic ligament were measured.At the same time,the age,height,weight and body mass index（BMI）of the three groups were measured and recorded.SPSS 22.0 statistical software package was used,and the measurement data were expressed as mean ± standard deviation（x±s）.Paired Wilcoxon rank sum test was used to compare the image quality scores between the two sequences.Analysis of variance and least significant difference（LSD）test were used to analyze the age,height,weight and BMI among the three groups.P<0.05 for the difference was statistically significant.Result:T1-StarVIBE sequence had no common motion artifacts in conventional VIBE sequence,the image scores of the two observers were significantly better than those of conventional sequence（P<0.001）,and the consistency between the observers was good（K=0.94 and K=0.92）;there was no statistical difference in age（P=0.051）and height（P=0.096）among the three groups（P>0.05）,but there was statistical difference in weight（F=17.16）and BMI（F=30.14）The average width of pubic symphysis was 3.90 ± 1.05mm,5.43 ± 1.06mm,4.22± 0.88mm,and the average thickness of anterior pubic ligament was 7.57± 1.44mm,13.30± 2.33mm The width of pubic symphysis and the thickness of anterior pubic ligament in the third trimester of pregnancy were higher than those in the non-pregnant women of childbearing age（P<0.05）,and the width of pubic symphysis and the thickness of anterior pubic ligament returned to the non-pregnant women of childbearing age on the 42 days after delivery（P>0.05）.There was no significant difference in the distance between pubic symphysis（P=0.13）and the thickness of anterior pubic ligament（P=0.12）between the two groups（P>0.05）.Conclusion:Free breathing T1-StarVIBE sequence has no motion artifact and has high tissue contrast,which can clearly show the anatomical structure of pubic symphysis;the distance between pubic symphysis and the thickness of anterior pubic ligament increase significantly in late pregnancy,and return to normal level 42 days after delivery,which provides an important reference standard for MRI evaluation of abnormal changes of pubic symphysis in late pregnancyPart 2.Quantitative Evaluation of Pubic Symphysis in Late Pregnancy Using T2*MappingBackground and purpose:T2*mapping sequence can indirectly evaluate the integrity of collagen fibers and the changes of free water according to different T2*values among different tissues,which can show the characteristics of deep cartilage and calcified layer,and is not sensitive to magic angle effect,so it can be used for multi-dimensional evaluation of full-thickness cartilage.The purpose of this study is to quantitatively evaluate the changes of T2*value in pubic symphysis fibrocartilage in late pregnancy by T2*mapping sequence Objective to compare the difference of T2*value of pubic symphysis cartilage among primipara in the third trimester of pregnancy,women in the second trimester of pregnancy and non pregnant women in childbearing age,so as to provide a reference standard for clinical application of MRI in evaluating abnormal changes of pubic symphysis in the third trimester of pregnancy.Materials and methods:A total of 61 primiparas in the third trimester of pregnancy（mean age:26.3 years;mean gestational weeks:32.2 weeks）,48 women in the second trimester of pregnancy（mean age:28.5 years;mean gestational weeks:31.9 weeks）and 64 women in the childbearing age（mean age:26.1 years）were included in this study.Both primiparas in the third trimester and women in the second trimester were singleton pregnancy.All subjects underwent axial T2*mapping sequence of pubic symphysis with 1.5T MRI.At the same time,the same level of anatomy and T2*map were selected and enlarged.On the axial T2*mapping（TE=11.83ms）articular cartilage map of the pubic symphysis,the pubic symphysis was manually divided into eight oval regions of interest（ROI）of left and right sides and anterior,middle and posterior subregions on both sides.The T2*value of the corresponding ROI was measured on the T2*pseudo color map.Analysis of variance and least significant difference（LSD）test were used to analyze the differences of age,height,weight,BMI and cartilage T2*value among the three groups;t test was used to compare the gestational weeks and weight gain of late pregnant primipara and second trimester women;Pearson correlation coefficient was used to analyze the correlation between pubic symphysis width and cartilage T2*value.P<0.05 for the difference was statistically significant.Results:there was no significant difference in age（P=0.123）,height（P=0.687）,weight（P=0.194）and BMI（P=0.350）among third trimester primiparas,second trimester women and non-pregnant women of childbearing age;there was no significant difference in gestational weeks（P=0.338）and weight gain（P=0.476）between third trimester primiparas and second trimester women.Left/right comparison showed that the difference of T2*value of pubic symphysis cartilage related to pregnancy was only found in the posterior region（left P=0.004;right P=0.002）,which suggested that the difference of T2*value of pubic symphysis cartilage between pregnant women and non-pregnant women of childbearing age was mainly driven by the posterior region.Compared with non-pregnant women of childbearing age,the T2*values of articular cartilage in the left side（P=0.006）and right side（P=0.032）of the pubic symphysis during pregnancy were significantly increased,but there was no difference in T2*values between primipara（P=0.143）and second trimester women（P=0.947）.There was a positive correlation between the width of pubic symphysis and the value of cartilage T2*in primipara group（r=0.47,P<0.001）,but there was no significant correlation between the width of pubic symphysis and the value of cartilage T2*in second trimester women（P=0.216）and non-pregnant women（P=0.635）.Conclusion:T2*mapping sequence is an effective quantitative method for MRI evaluation of pubic symphysis cartilage;T2*value of pubic symphysis cartilage in late pregnancy is significantly increased,and the difference is mainly driven by the posterior region.The results of this quantitative study will provide an important reference standard for using T2*mapping sequence to evaluate the abnormal changes of pubic symphysis in late pregnancy.Part 3:Quantitative Evaluation of the Fibrocartilage Between Pubic Symphysis in Patients with Symphysis Pain in the Late Pregnancy Using T2*mappingBackground and objective:pregnancy associated pubic symphysis dysfunction（PSD）is characterized by severe pain in the pubic symphysis area.The incidence rate and recurrent rate of recurrent pregnancy are higher.It seriously affects the quality of life and physical and mental health of patients.This study explored the changes of pubic symphysis and fibrocartilage in patients with pubic symphysis pain during late pregnancy by T2*mapping imaging,and combined with routine T1-StarVibe.Objective to calculate the distance between the pubic symphysis and find out the potential causes of pain in the pubic symphysis region,so as to provide imaging basis for early clinical diagnosis and timely preventive measures.Materials and methods:36 patients（mean age:27.1 years,mean gestational age:32.5 weeks）with pubic symphysis pain in the third trimester of pregnancy were selected as the study group,and 40 normal pregnant women matched with age and gestational age were selected as the control group.All subjects were singleton pregnant women,and 1.5T MRI was used for axial T1-starvibe and T2*mapping sequence scanning of pubic symphysis.The width of the pubic symphysis was measured on the conventional T1-StarVIBE,and the ROC curve was drawn to verify the diagnostic efficacy of the width of the pubic symphysis in patients with pubic symphysis pain;on the T2*mapping map,the anterior,middle and posterior regions of interest（ROI）were hand drawn along the left and right sides of the cartilage,and the T2*value was measured.The differences of pubic symphysis width and fibrocartilage T2’ between the two groups were compared by independent sample t test.Results:Compared with the control group,the distance of pubic symphysis was wider in patients with pubic symphysis pain in the third trimester of pregnancy;ROC curve showed that the diagnostic accuracy of the width of pubic symphysis in patients with pubic symphysis pain in the third trimester of pregnancy was as high as 88.5%;Combined analysis of pubic symphysis width and T2*value of pubic symphysis cartilage showed that its diagnostic efficacy was 89.1%,which was very small compared with 88.5%of pubic symphysis width.There was no statistical difference between the two ROC curves（P>0.05）,the T2*value of anterior and middle part of fibrocartilage between pubic symphysis were significantly increased（P=0.049;P=0.024）,and there was no significant difference in the T2*value of posterior part（P>0.05）.Conclusion:T2*mapping imaging can objectively and quantitatively evaluate the changes of fibrocartilage in the pubic symphysis associated with pregnancy,which can provide imaging basis for early clinical diagnosis and prevention of further development of patients with pubic symphysis pain.The degeneration of the anterior and middle part of the pubic symphysis and the widening of the distance between the pubic symphysis may be the potential mechanism of pubic symphysis pain. |
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