Objective:To explore the application value of fetal heart ultrasound image segmentation network model based on knowledge distillation technology in the fine segmentation of fetal heart ultrasound image at three-vessel and trachea (3VT) views.Methods:One thousand and three hundred fetals were retrospectively collected from Sir Run Run Shaw Hospital, Zhejiang University College of Medicine from January 2016 to December 2021, the two-dimensional grayscale ultrasound images of fetal heart at 3VT views were analyzed and then divided into training, validation, and test sets. The training and validation sets were used to construct the auxiliary diagnostic network models, and the test set was used to test the reliability of different network models (U-Net, DeepLabv3+ ). The 3VT views were collected and annotated by an experienced doctor as the reference standard. The intersection over union (IoU), pixel accuracy (PA) and Dice coefficient (Dice) were used as the 3 indexes to evaluate the segmentation accuracy, and the diagnostic efficiency of the training model was evaluated. The training model and the most commonly used segmentation models were identified, and the results were compared. A total of 101 images were randomly selected and assigned to junior doctors, AI and junior doctors assisted AI interpretation. Bland-Altman images were drawn to evaluate their consistency with the reference standard, and the results were compared.Results:The training model of knowledge distillation algorithm achieved better results than U-Net, DeepLabv3+ models on all evaluation indexes, and the average IoU, PA and Dice were 68.6%, 81.4% and 81.3%, respectively. Compared with the U-Net model and DeepLabv3+ model, more accurate segmentation boundaries were obtained by the knowledge distillation algorithm training model, and the quantitative evaluation indexes were improved. With the aid of the model, the diagnostic accuracy of junior doctors was improved.Conclusions:The knowledge distillation algorithm training model segmentation method can identify the anatomical structure of the fetal heart in the 3VT view of the fetal heart ultrasound image, and the recognition result is obviously better than other related methods, and can improve the accuracy of image recognition for doctors with low experience.

Objective:To evaluate the morphological characteristics of the fetal heart and the contractile function of the left and right ventricles in fetuses with pulmonary stenosis (PS) and pulmonary atresia (PA) using fetal heart quantitative analysis technology (fetal HQ), and to assess the impact of different degrees of right ventricular outflow tract obstruction (RVOTO) on the contractile function of the fetal left and right ventricles. To accumulate early data and explore parameters for constructing a predictive model and clinical decision-making tool for the progression of fetal PS and PA.Methods:A retrospective analysis was conducted on 42 cases of mild to moderate PS and 23 cases of severe PS or PA detected through fetal echocardiography in the Department of Ultrasound, Sir Run Run Shaw Hospital, School of Medicine, Zhejiang University, from July 2020 to December 2021. A control group of 195 normal fetal cases matching gestational weeks was selected. The fetal HQ technique was employed to measure the global sphericity index (GSI), left ventricular ejection fraction (EF), left/right ventricular area change percentage (LVFAC, RVFAC), and left/right ventricular longitudinal strain (LVGLS, RVGLS). Additionally, 24-segment sphericity index (SI) and fractional shortening (FS) for both left and right ventricles were measured. Comparative analyses were performed between the case and control groups, as well as within the case group.Results:In comparison with the control group, the case group exhibited significantly decreased GSI, LVGLS, LVEF, LVFAC, RVGLS, and RVFAC.The differences were statistically significant in the mild to moderate PS group (all P<0.05) and highly significant in the severe PS/PA group (all P<0.01). In the mild to moderate PS group, the left ventricle′s 2nd segment, right ventricle′s 24th segment SI, and the left ventricle′s 1st-13th segments, right ventricle′s 1st-16th and 20th-24th segments FS showed statistically significant differences compared to the control group (all P<0.05). In the severe PS/PA group, the right ventricle′s 1st-22nd segment SI, and the left ventricle′s 6th-13th, 21st-24th segments, and the right ventricle′s 1st-14th segments FS were reduced, showing statistically significant differences compared to the control group (all P<0.05). The severe PS/PA group showed lower RVGLS, RVFAC, and SI for the right ventricle′s 1st to 17th segments when compared to the mild to moderate PS group, with statistically significant differences (all P<0.05). Conclusions:Quantitative indices derived by fetal HQ is capable of evaluating the cardiac morphology and function of fetuses with PS/PA, which may provide for reference information for comprehensive understanding of cardiac morphological and functional changes in such fetuses.

Objective:To explore the potential application of two-dimensional speckle tracking echocardiography (2D-STE) in terms of quantification and evaluating left and right atrial function in normal fetuses, and to investigate the relevant factors affecting left and right atrial function in normal fetuses as well as differences between both atrial function.Methods:A total of 100 single fetuses underwent fetal echocardiography in the Department of Diagnostic Ultrasound & Echocardiography, Sir Run Run Shaw Hospital, Zhejiang University College of Medicine from January 2019 to October 2022 were retrospectively enrolled. The standard basal or apical four-chamber view clips were obtained, and the left and right atrial function were quantitatively analyzed using TomTec-ARENA off-line cardiac analysis software for quantitative assessment of both atrial strain measurements including left atrial reservoir phase longitudinal strain (LASr), left atrial ductal phase longitudinal strain (LAScd), left atrial systolic phase longitudinal strain (LASct), right atrial reservoir phase longitudinal strain (RASr), right atrial ductal phase longitudinal strain (RAScd), right atrial systolic phase longitudinal strain (RASct), and the ratio of systolic longitudinal strain to conduit longitudinal strain in left and right atrial systolic display groups were calculated which was denoted as Sct/Scd.Routine fetal obstetric ultrasound measurements and fetal echocardiographic parameters in the two groups were obtained including fetal heart rate (FHR), left atrial end-systolic length (LAESL), left atrial end-systolic diameter (LAESD), left atrial end-systolic area (LAESA), left ventricular end-diastolic transverse diameter (LVEDD), right atrial end-systolic length (RAESL), right atrial end-systolic diameter (RAESD), right atrial end-systolic area (RAESA), right ventricular end-diastolic transverse diameter (RVEDD), peak blood flow velocity of mitral valve and tricuspid valve in early and late diastolic period (E, A), peak ratio of E and A: E/A (MV), E/A (TV), and the difference between the left and right atrial strain indices and the routine fetal obstetric ultrasound and fetal echocardiographic parameters, as well as the correlation between the above parameters and gestational age were analyzed. The repeatability tests were performed using the intra-class correlation coefficientt (ICC).Results:Significant differences were found in LASr and RASr, LAScd and RAScd, LASct and LAScd, Sct/Scd between the left atrium and right atrium, E/A (MV) and E/A (TV), LAESD and RAESD, LAESL and RAESL (all P<0.05), there was significant difference in FHR between the left atrial contraction display group and the no atrial contraction display group ( P=0.011), no significant difference in other parameters (all P>0.05). Correlation analysis showed that, LASr, LASct, RASr, and RASct showed moderate negative correlation with gestational age ( rs=-0.570, -0.601, -0.469, -0.568; all P<0.001). While LAScd, RAScd, E/A (MV), E/A (TV) were moderately positively related with gestational age ( rs=0.310, 0.350, 0.330, 0.343; all P<0.05). LAESL, LAESD, LAESA, RAESL, RAESD, RAESA, LVEDD and RVEDD were significantly positively related with gestational age ( rs=0.662, 0.768, 0.792, 0.728, 0.828, 0.822, 0.838, 0.802, all P<0.001). The inter-examiner ICC of fetal LASr and RASr were 0.89 and 0.84 (both P<0.05) and the intra-examiner ICC of fetal RASr and LASr both were 0.80 (both P<0.05), with good consistency. Conclusions:2D-STE is highly feasible and reproducible in assessing fetal atrial function. The corresponding variation values of fetal atria at different gestational weeks were obtained in this study, which provides a new reference index for us to further study normal fetal atria as well as comparative analysis of fetal cardiac function under prenatal pathological conditions.

Objective:To explore the potential application of two-dimensional speckle tracking echocardiography (2D-STE) in terms of quantification and evaluating left atrial function in normal fetuses and fetuses with left ventricular outflow tract obstruction (LVOTO).Methods:A total of 32 fetuses diagnosed with LVOTO, who underwent fetal echocardiography at Sir Run Run Shaw Hospital, Zhejiang University College of Medicine between May 2020 to June 2022, were selected as the case group, and 100 pregnant women with normal singleton fetuses between January 2019 to October 2022 were chosen as the control group. The standard basal or apical four-chamber view clips were obtained and were quantitatively analyzed using TomTec-Arena off-line cardiac analysis software to obtain the left atrial strain parameters of the two groups of fetuses including left atrial reservoir phase longitudinal strain(LASr), left atrial ductal phase longitudinal strain(LAScd), left atrial systolic phase longitudinal strain (LASct), as well as the routine obstetric ultrasound measurements and fetal echocardiographic parameters of the two groups: biparietal diameter (BPD), femur length (FL), aortic annulus end-systolic inner diameter (AO), pulmonary annulus end-systolic inner diameter (PA), left atrial end-systolic long length (LAESL), left atrial end-systolic transverse diameter (LAESD), right atrial end-systolic long length (RAESL), right atrial end-systolic transverse diameter (RAESD), left ventricular end-diastolic transverse diameter (LVEDD) and right ventricular diastole end-diastolic transverse diameter (RVEDD). The ratio of right ventricular end-diastolic transverse diameter to left ventricular end-diastolic transverse diameter (RVd/LVd) and the ratio of pulmonary annulus diameter to aortic annulus diameter (PA/AO) were calculated. The differences of strain parameters between the two groups were compared, and the correlation between strain parameters and gestational age, RVd/LVd and other conventional measurement parameters were analyzed. ROC curve was used to compare the specificity and sensitivity of LASr and RVd/LVd in evaluating fetal cardiac dysfunction with LVOTO.Results:There were significant differences in LASr, LAScd, LASct, MAPSE, AO, LAESL, LVEDD, RVd/LVd and PA/AO between the two groups (all P<0.05), there were no significant differences in other parameters (all P>0.05). Correlation analysis showed that LASr was negatively correlated with RVd/LVd in LVOTO group ( rs=-0.394, P=0.025), and LASct was negatively correlated with RVd/LVd ( rs=-0.626, P=0.004). In the control group, LASr was negatively correlated with gestational age, AO and PA ( r/ rs=-0.570, -0.440, -0.493; all P<0.001), and LASct was negatively correlated with gestational age, AO and PA ( r/ rs=-0.601, -0.532, -0.568; all P<0.001). LAScd was positively correlated with gestational age, AO and PA ( r/ rs=0.310, 0.370, 0.314; all P<0.05). There were no significant correlations between the other parameters (all P>0.05). ROC curve analysis showed that the area under the curve(AUC) in LASr evaluation of fetal cardiac dysfunction with LVOTO was 0.890 (0.826, 0.953) and the AUC in RVd/LVd evaluation of fetal cardiac dysfunction with LVOTO was 0.742 (0.637, 0.846), there were significant differences between them( P<0.05). Conclusions:2D-STE is highly feasible and reproducible in assessing fetal left atrial function. Evaluation of fetal left atrial function by 2D-STE provides a new reference index for quantitative analysis of fetal cardiac dysfunction.

Objective To observe the correlations of two-dimensional speckle tracking imaging(2D-STI)parameters of healthy fetal heart and gestational age in middle and late pregnancy.Methods Fetal echocardiography was prospectively performed in 279 healthy singleton fetuses in middle and late pregnancy.The fetuses were divided into group A(20-23+6 weeks of pregnancy,n=49),B(24-27+6 weeks of pregnancy,n=112),C(28-31+6 weeks of pregnancy,n=63),D(32-35+6 weeks of pregnancy,n=30)and group E(≥36 weeks of pregnancy,n=25)according to gestational age.Fetal left ventricle(LV)ejection fraction,LV and right ventricle(RV)area change fraction,LV and RV global radial strain(GRS),LV and RV myocardium and endocardium global longitudinal strain(MyoGLS,EndoGLS),LV myocardium and endocardium global circumferential strain(MyoGCS,EndoGCS)were obtained with 2D-STI and compared among 5 groups,and the correlations with gestational age were analyzed.Results Significant differences of fetal LV EndoGLS was found among 5 groups(P=0.044).Fetal LV GRS and RV GRS were positively correlated with gestational age(r=0.165,0.122,both P＜0.05)in middle and late pregnancy,while the absolute value of LV EndoGLS was negatively correlated with gestational age(r=-0.133,P=0.026).Conclusion LV GRS and RV GRS were positively correlated with gestational age in healthy fetuses in middle and late pregnancy,while the absolute value of LV EndoGLS was negatively correlated with gestational age.