| Objectives:In this study, we used the 3DUS to measure the size of auricle, to explore the relationship between the size of fetal auricle and the various growth parameters in different gestation age. The morphological characteristics of fetal auricular in 3DUS was described in different GA. To investigating the method of fetal external auditory meatus ultrasonography with 2DUS and 3DUS, and exploring the morphology characteristics in 2DUS and 3DUS.in the First Affiliated Hospital of Fujian Medical University from Dec. 2013 to Jan. 2015.The instrument were Philips IU22, Philips IU Elite, GE Voluson E8 color doppler ultrasonic diagnostic apparatus with 3D volume transducer. The 2D and 3D ultrasound images of the external ear which close to the probe were captured by the volume transducer and 2D matrix array probes. Firstly,2D images were used to observing the shape of the fetal auricle and external auditory canal and saving the images in workstation, secondly, the length and width of external auditory canal were measured, then offline processed the 3D volume data. Observing and analyzing the 3D images features of auricle and external auditory canal, the length and width of auricle were measured. Every fetal auricle and external auditory canal was followed after birth.Results : 178 cases of 11-40 weeks fetal external ear images in 214 cases were successfully displayed,the display ratio among 11-13+6week group was 76.19%(16/21), 14-18+6 week group was 75.00%(12/16), 19-23+6 week group was 88.68%(47/53),24-27+6week group was 88.89%(32/36),28-32+6week group was 76.92%(30/39), 33-36+6week group was88.24%(30/34), 37-40 week group was73.33%(11/15). We analysed the correlation between the fetal ear length,width and GA,the correlation coefficient r was 0.95 and 0.95 respectively, Spearman test sided P values were less than 0.01, it was a statistically significant. We considered that it was a linear correlation between fetal ear length, width and GA. The regression equations were YL=0.111X-0.560 and YW=0.071X-0.484,YL and YW were supposed to represent the for the length of the auricle and the width of the auricle, respectively, the unit was cm, X was supposed to represent the fetal gestational age, the unit was weeks. The fetal auricle can be full displayed by 3DUS. Fetal auricle can be displayed as early as 11 weeks 5 days pregnant on the 3DUS.The auricle was small in 11-13+6 weeks, it was just a nodular bulge,i It was unable to distinguish the component of auricle.The components of the auricle can be displayed with the increasing of GA,and the length and width of auricle also increased. The fetuses in 33 weeks have the basic shape of auricle shape and similar to adults, the helix, antihelix and tragus, on tragus and cavity of auricular concha, etc can be displayed.The fetal external auditory canal can be displayed as early as 21 weeks 5 days by 2DUS.The 2DUS detection rate of external auditory canal of 19-23+6 fetus was 9.43%(5/53),the display ratio among 24-27+6 week group was 55.56%(20/36),28-32+6week group was 74.36%(29/39), 33-36+6week group was 79.41%(27/34),37-40 week group was73.33%(11/15). The display ratio showed no significant differenceamong late pregnancy group. The application of 2DUS in late pregnancy by orbital-ear level section(transverse section) and brain coronal section can clearly display the fetal external ear canal, the rate of transverse section and coronal section in the external auditory canal showed no obvious difference. The 2DUS can display the fetal external auditory canal as early as 21 weeks 5 days. The cross section showed a low-no echo crack, was the continuation of a cavity inside the ear, from outside to inside diameter of taper faded away until invisible, the internal showed low weak echo disappear gradually. The fetal external auditory canal inward become further deepen at 23 weeks, showed a low echo to the inner side of the fracture and soft tissue extension. Until 27 weeks the fetal external auditory canal has been basically formed, the no echo pipeline was clearly showed. The mouth of the ear slightly back in shape in cross section, the inner side section perpendicular to the skin to the inside when oblique probe to the side of fetal foot slightly. The visible outer segments from outside to inclined inwards out of shape in coronal section, the inner side section showed slightly upward curved shape to the inside, from outside to inside the lumen was tapering. The fetal ear canal was larger in late pregnancy, were consistent with the 27 weeks.The fetal external auditory canal showed difficult in the second trimester of pregnancy. It can be displayed as early as 27 weeks by 3DUS.The 3DUS detection rate of external auditory canal of 28-32+6 was 33.33%(13/39),33-36+6 week group was 29.41%(10/34), 37-40 week group was 46.67%(7/15). Using slice from front to back layer on front and rear view, and adjusting the threshold, gray, X, Y, and Z axis angle carefully,The external auditory canal can be showed. It was a visible to take the shape of the pipe from outside the mouth position inward to the inner side. The application of slice forward in craniocerebral view below on the side of head to the leg, visible outside the mouth ear backward slightly out of shape, the inner part was perpendicular to the skin in shape, tapering from the outside to the inside of the lumen.Conclusions: 1. The rate of fetal auricle with 3DUS is high, the 3D images can provide detailed morphological information, to help the diagnosis of auricle malformation. 2. Fetal auricle size showed significant positive correlation with GA.The relationship between fetal ear length, width and gestational age by following formula: YL=0.111X-0.560, YW=0.071X-0.484, YL and YW were supposed to represent the for the length of the auricle and the width of the auricle respectively, the unit was cm, X was supposed to represent the fetal gestational age, the unit was weeks. 3.The observation of external auditory canal was feasible in prenatal ultrasound imaging, can provide a reference plane in the diagnosis of atresia. The observation of external auditory canal in 2DUS was earlier than 3DUS, 2DUS was the foundation of 3DUS in detection of external auditory meatus. 4.Fetal external ear canal can be showed early in the 21 week with 2DUS, with the increasing of GA,the ratio of display was improved gradually. The external auditory canal can be displayed in orbital-ear transverse section and coronal section with 2DUS, and the two kinds of methods showed no significant difference. 5. The length and width of external auditory canal increased with GA. The main factors which affected the two-dimensional ultrasound detection rate of external auditory canal were fetal gestational size, fetal position and amniotic fluid volume. |
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