Monochorionic twins are at risk for complications due to the presence of placental vascular anastomoses, including twin-twin transfusion syndrome, twin anemia-polycythemia sequence, selective fetal growth restriction, and twin reversed arterial perfusion sequence. While ultrasound is the primary modality to screen for the development of these complications, MRI plays an important role in assessing monochorionic twin pregnancies for the development of other complications, such as neurologic injury. In this article, the authors review the ultrasound imaging findings associated with monochorionic twin complications, management options, and the role for MRI in these pregnancies.

暂无摘要。

A major obstacle in applying machine learning for medical fields is the disparity between the data distribution of the training images and the data encountered in clinics. This phenomenon can be explained by inconsistent acquisition techniques and large variations across the patient spectrum. The result is poor translation of the trained models to the clinic, which limits their implementation in medical practice. Patient-specific trained networks could provide a potential solution. Although patient-specific approaches are usually infeasible because of the expenses associated with on-the-fly labeling, the use of generative adversarial networks enables this approach. This study proposes a patient-specific approach based on generative adversarial networks. In the presented training pipeline, the user trains a patient-specific segmentation network with extremely limited data which is supplemented with artificial samples generated by generative adversarial models. This approach is demonstrated in endoscopic video data captured during fetoscopic laser coagulation, a procedure used for treating twin-to-twin transfusion syndrome by ablating the placental blood vessels. Compared to a standard deep learning segmentation approach, the pipeline was able to achieve an intersection over union score of 0.60 using only 20 annotated images compared to 100 images using a standard approach. Furthermore, training with 20 annotated images without the use of the pipeline achieves an intersection over union score of 0.30, which, therefore, corresponds to a 100% increase in performance when incorporating the pipeline. A pipeline using GANs was used to generate artificial data which supplements the real data, this allows patient-specific training of a segmentation network. We show that artificial images generated using GANs significantly improve performance in vessel segmentation and that training patient-specific models can be a viable solution to bring automated vessel segmentation to the clinic.

BACKGROUND: Our objective was to investigate the association between the presence of placental anastomoses and intertwin differences in renin-angiotensin-aldosterone activation in monochorionic twins using amniotic fluid aldosterone (AF-ALD) levels. In addition, this study also examined the association between AF-ALD and the ALD levels in the umbilical cord blood (UCB-ALD) in monochorionic twins.
METHODS: This prospective study included monochorionic diamniotic (MD) twin pregnancies that were not complicated by twin-to-twin transfusion syndrome (TTTS) at delivery. Amniotic fluid and umbilical cord vein blood samples were collected from each twin at delivery, and the ALD levels were measured subsequently. The MD twins were divided into two groups: those with placental anastomoses and those without anastomoses owing to fetoscopic laser surgery. The differences in the AF-ALD levels between the larger and smaller twins were analyzed.
RESULTS: The AF-ALD levels showed a strong and significant positive correlation with UCB-ALD levels in 131 MD twins (r = 0.804, p < 0.001). Intertwin differences were examined in 41 and 28 pairs of MD twins with and without placental anastomoses, respectively. The AF-ALD levels in the smaller twins were significantly higher than those in the larger twins among the pairs of MD twins with placental anastomoses (p = 0.003); however, no statistically significant intertwin differences were observed among the twins without placental anastomoses (p > 0.05).
CONCLUSIONS: The AF-ALD levels reflect the UCB-ALD levels in MD twins. The presence of placental anastomoses led to intertwin discordance in the ALD levels in MD twins even uncomplicated with TTTS. It was considered that monochorionic twins have this clinical background, and it leads to the development of TTTS.

OBJECTIVE: Low birthweight may have adverse sequelae in later life. Therefore, we analyzed behavioral difficulties and salivary glucocorticoid profiles in monozygotic twins with intra-twin birthweight differences due to twin-to-twin transfusion syndrome (TTTS).
METHODS: 46 monozygotic TTTS twin pairs with birthweight differences of <1SDS (concordant; n=29) and ≥1SDS (discordant; n=17) were recruited at a mean age of 6.9 years for a prospective longitudinal cohort study. For glucocorticoid analysis, saliva samples were collected (at 7 h, 13 h, 18 h and 21 h) and analyzed with liquid chromatography-tandem mass spectrometry. Parents completed the Strengths and Difficulties Questionnaire.
RESULTS: From the parents\' perspective, the formerly smaller twins had statistically higher scores regarding hyperactivity (mean 4.63 vs 3.48, p=0.003) and emotional problems (mean 2.67 vs 2.02, p=0.042). Less catch-up growth (Δintra-twin height SDS 4 years of age - Δintra-twin birth length SDS) of the smaller twins was associated with higher scores for hyperactivity (Adj. R²=0.261, p<0.001, β=-1.88, F(1.44)=16.86, n=46, f²=0.35), while smaller birthweight (Adj. R²=0.135, p=0.007, β=-0,87, F(1.44)=8.03, n=46, f²=0.16) and birth length (Adj. R²=0.085, p=0.028, β=-0,78, F(1.44)=5.19, n=46, f²=0.09) were associated with higher scores for peer problems. Greater Δintra-twin for cortisol (7 h: rho=0.337, p=0.029; cumulative: rho=0.458; p=0.024) and cortisone (7 h: rho=0.329, p=0.029; 13 h: rho=0.436, p=0.005) correlated with a greater Δintra-twin for conduct problems. In the discordant group, circa 1 SDS in head circumference persisted from birth (mean SDS: smaller twin -1.18, larger twin -0.08, p<0.001) to present (mean SDS: smaller twin -1.16, larger twin -0.14, p<0.001).
CONCLUSIONS: Higher cortisol and cortisone concentrations in smaller twins were associated with higher scores for conduct problems. Lower birthweight and absent catch-up growth affected the parents\' perspective on the smaller twins\' behavior. They saw those children as more hyperactive, with more peer problems and emotional problems. Thus, it seems important to introduce regular check-ups where behavioral difficulties can be assessed, and assistance and advice can be given to the families. Due to the persisting smaller head circumference in the smaller discordant twins, this should be measured regularly.

To evaluate maternal and perinatal outcomes following fetal intervention in the context of maternal \"mirror\" syndrome.
A multicenter retrospective study of all cases of fetal hydrops complicated by maternal \"mirror\" syndrome and treated by any form of fetal therapy between 1995 and 2022. Medical records and ultrasound images of all cases were reviewed. \"Mirror\" syndrome was defined as fetal hydrops and/or placentomegaly associated with the maternal development of pronounced edema, with or without pre-eclampsia. Fetal hydrops was defined as the presence of abnormal fluid collections in ≥2 body cavities.
Twenty-one pregnancies met the inclusion criteria. Causes of fetal hydrops and/or placentomegaly included fetal lung lesions (n = 9), twin-twin transfusion syndrome (n = 6), severe fetal anemia (n = 4), and others (n = 2). Mean gestational age at \"mirror\" presentation was 27.0 ± 3.8 weeks. Maternal \"mirror\" syndrome was identified following fetal therapeutic intervention in 14 cases (66.6%). \"Mirror\" symptoms resolved or significantly improved before delivery in 8 (38.1%) cases with a mean interval from fetal intervention to maternal recovery of 13.1 days (range 4-35). Three women needed to be delivered because of worsening \"mirror\" syndrome. Of the 21 pregnancies treated (27 fetuses), there were 15 (55.5%) livebirths, 7 (25.9%) neonatal deaths and 5 (18.5%) intra-uterine deaths.
Following successful treatment and resolution of fetal hydrops, maternal \"mirror\" syndrome can improve or sometimes completely resolve before delivery. Furthermore, the recognition that \"mirror\" syndrome may arise only after fetal intervention necessitates hightened patient maternal surveillance in cases of fetal hydrops.

OBJECTIVE: To describe fetal brain Magnetic Resonance Imaging (MRI) findings in a large series of monochorionic (MC) pregnancies complicated by Twin Anemia-Polycythemia Sequence (TAPS) prenatally diagnosed, so to characterize the potential intracranial complications associated with this condition, their frequency and potential treatment options.
METHODS: This is a retrospective study of MC twin pregnancies complicated by TAPS and undergone fetal MRI in a single institution from 2006 to 2023. MRI control was performed and post-natal ultrasound (US) or MRI were available.
RESULTS: 1250 MC pregnancies were evaluated in our institution. 50 pregnancies (4%) were diagnosed with TAPS, 29 underwent a fetal brain MRI. 13/29 pregnancies (44.8%) demonstrated brain findings at MRI in at least a twin. Neuroradiological findings were detected in 14/57 twins (24.6%). We detected four main categories of findings: hemorrhagic lesions, T2-weighted white-matter hyperintensities (WMH), brain edema-swelling and venous congestion. Nineteen findings were present in the anemic and three in the polycythemic twins, with a statistically significant ratio between the two groups (p-value = 0.01). Intrauterine MRI follow-up demonstrated the sequalae of hemorrhagic lesions. A complete regression of brain swelling, veins prominence and T2-WMHs was demonstrated after treatment. Postnatal imaging confirmed prenatal features.
CONCLUSIONS: Our work demonstrates that TAPS-related MRI anomalies consisted in edematous/hemorrhagic lesions that occur mostly in anemic rather than in polycythemic twins. Fetoscopic laser surgery could have a potential decongestant role. Therefore, prenatal MRI may help in counselling and management in TAPS pregnancies, especially for the planning of therapy and the monitoring of its efficacy.

This systematic review explores cardiac adaptation in monochorionic (MC) twins with twin-twin transfusion syndrome (TTTS) or selective fetal growth restriction (sFGR) and assesses the risk of congenital heart defects (CHDs).
Adhering to PRISMA guidelines, 63 studies were reviewed (49 on cardiac adaptation, 13 on CHD, one on both). A narrative synthesis of cardiac adaptation patterns was performed. Additionally, a meta-analysis compared the livebirth prevalence of CHD in TTTS and sFGR against uncomplicated MC twins.
In TTTS recipients, cardiac function may be impaired for diastolic, systolic, as well as global functions, while in donors, cardiac function is generally preserved. In sFGR, large twins may show hypertrophic cardiomyopathy, and small twins may show impaired systolic function. Co-occurrence of TTTS and sFGR magnifies cardiac impact but is often underreported. Meta-analysis for CHD prevalence revealed a relative risk ratio of 3.5 (95% CI: 2.5-4.9) for TTTS and 2.2 (95%CI: 1.3-3.5) for sFGR compared with uncomplicated MC twins.
This study highlights the well-documented cardiac adaptation in TTTS, contrasting with limited understanding in sFGR. Elevated CHD risks were observed in both conditions. Enhanced cardiovascular surveillance is warranted in complicated MC twin pregnancies. Future research should explore cardiac adaptation in sFGR and its long-term consequences.

Antenatal management of monochorionic pregnancies complicated by twin anemia polycythemia sequence (TAPS) remains sub-optimally defined. Our objective was to evaluate the safety and efficacy of fetoscopic selective laser photocoagulation with respect to fetal and neonatal survival.
A case series is reported with patients referred to the Texas Children\'s Fetal Center for evaluation and management of suspected spontaneous TAPS without concomitant twin-to-twin syndrome from 2014 to 2023. All evaluations were performed by our team and patients with stage II-IV TAPS were offered expectant management, intrauterine transfusion, or laser therapy. Cases of post-laser TAPS were excluded from this study. Pregnancy and neonatal outcomes were obtained from electronic medical records.
During a 10-year time period, 18 patients presented to our center for the management of TAPS. Thirteen patients had stage II-IV TAPS (13/18, 72%) and elected to proceed with laser photocoagulation. All procedures were completed, and \"solomonization\" was performed for 12/13. Normalization of middle cerebral artery Dopplers in both fetuses was noted after all cases. There was one intrauterine fetal death of the 26 viable fetuses after laser treatment, which was complicated by selective growth restriction. Most patients (12/13) were delivered by Cesarean section at a mean gestational age of 29 ± 3 weeks. Subsequently, there was one ex-donor neonatal death in an infant who had prenatal hydrops. Overall, 30-day postnatal survival was 24/26 fetuses (92.3%).
In the setting of spontaneous TAPS, laser therapy is feasible and appears to be an effective approach with overall favorable perinatal outcomes.

UNASSIGNED: It was to explore the ultrasonic characteristics of complications of twin pregnancies with monochorionic diamniotic (MCDA) during various pregnancy periods and the differences in pregnancy outcomes.
UNASSIGNED: One hundred pregnant women with MCDA were included in the study. They were rolled into a complication group (44 cases) and a non-complication group (56 cases) according to whether they had complications. The pulsatility index (PI), resistance index (RI), and systolic/diastolic (S/D) values of ultrasound in pregnant women and the final neonatal situation at each time period were compared and analyzed.
UNASSIGNED: In pregnant women with twin-twin transfusion syndrome (TTTS), there was no significant difference in RI and S/D values between the larger and smaller twin during pregnancy (P > .05). Compared to the group without complications, the incidence of neonatal death was significantly increased in the complication group, and the newborn\'s weight, length, head circumference, and Apgar score were significantly lower (P < .05). In pregnant women with selective intrauterine growth restriction (sIUGR), the RI and PI values of the larger twin were significantly higher than those of the smaller twin during pregnancy, and S/D values were significantly lower (P < .05). The newborns in the group without complications had significantly higher body weight, length, and head circumference (P < .05). In pregnant women with gestational diabetes mellitus (GDM), there was no significant difference in RI and S/D values between the larger and smaller twin during pregnancy (P > .05), and there were no significant differences in other indicators compared to the group without complications. In pregnant women with premature rupture of membrane (PROM), there was no significant difference in RI and S/D values between the larger and smaller twin during pregnancy (P > .05), but the newborns in the group without complications had significantly higher weight, length, Apgar score, and lower incidence of neonatal death (P < .05). In pregnant women with preeclampsia (PE), there was no significant difference in RI and S/D values between the larger and smaller twin during pregnancy (P > .05), and there were no significant differences in other indicators compared to the group without complications (P > .05).
UNASSIGNED: Pregnant women with sIUGR had significantly higher RI and PI values in the larger twin and significantly lower S/D values compared to the smaller twin during pregnancy, while no significant differences were observed for other complications. The combination of TTTS and PROM decreased the birth weight, body length, head circumference, and Apgar score of twins and increased the mortality rate.