Point Cloud Completion: A Survey.

Point cloud completion is the task of producing a complete 3D shape given an input of a partial point cloud. It has become a vital process in 3D computer graphics, vision and applications such as autonomous driving, robotics, and augmented reality. These applications often rely on the presence of a complete 3D representation of the environment. Over the past few years, many completion algorithms have been proposed and a substantial amount of research has been carried out. However, there are not many in-depth surveys that summarise the research progress in such a way that allows users to make an informed choice of what algorithms to employ given the type of data they have, the end result they want, the challenges they may face and the possible strategies they could use. In this study, we present a comprehensive survey and classification of papers on point cloud completion untill August 2023 based on the strategies, techniques, inputs, outputs, and network architectures. We will also cover datasets, evaluation methods, and application areas in point cloud completion. Finally, we discuss challenges faced by the research community and future research directions.

Evaluating skeletal dysplasias on prenatal ultrasound: an emphasis on predicting lethality.

Lethal skeletal dysplasias can be diagnosed by prenatal ultrasound (US) using several sonographic parameters. Degree of femoral shortening, lung volumes, femur length to abdominal circumference ratio, and chest circumference to abdominal circumference ratio are the most sensitive and specific predictors. Although there are more than 450 different skeletal dysplasias, only a few are lethal in the perinatal period. We review current fetal US literature and present an updated algorithmic approach to first establish lethality and, second, evaluate for hallmark sonographic features to help determine a specific diagnosis.

Neonatal Outcomes in Fetuses With a Persistent Intrahepatic Right Umbilical Vein.

OBJECTIVES: A fetal persistent intrahepatic right umbilical vein has been linked to anomalies and genetic disorders but can be a normal variant. We conducted a retrospective review to determine other sonographic findings that can stratify fetuses for further evaluation. METHODS: A total of 313 fetuses had a persistent intrahepatic right umbilical vein identified on 17- to 24-week sonography. The outcome was any major congenital anomaly or an adverse neonatal outcome, which was defined as aneuploidy, fetal demise, or neonatal death. RESULTS: A total of 217 patients (69.3%) had a normal neonatal outcome. Sixty-nine patients (22.0%) were lost to follow-up. Five fetuses (2.1%) had aneuploidy; 4 of the 5 had additional sonographic findings, and 1 had an isolated persistent intrahepatic right umbilical vein. Twenty-four fetuses had a major anomaly in association with the persistent right umbilical vein; 26 additional fetuses had soft sonographic markers associated with karyotypic abnormalities but were chromosomally normal. Of those with adverse neonatal outcomes, 12 had a congenital heart defect (57%). An additional sonographic finding with a persistent intrahepatic right umbilical vein was predictive of a congenital anomaly or an adverse neonatal outcome (P < .001), with a positive predictive value of 44.0% (95% confidence interval, 30.0%-58.7%). An isolated persistent intrahepatic right umbilical vein had a 0.4% risk for a congenital anomaly or an adverse neonatal outcome. CONCLUSIONS: A persistent intrahepatic right umbilical vein should prompt an extended anatomic survey and a fetal cardiac evaluation. If the survey and cardiac anatomy are reassuring, no further follow-up is needed. If additional findings are identified, genetic counseling and invasive testing should be considered.

Sonographic biometry in the early third trimester: A comparison of parameters to predict macrosomia at birth.

PURPOSE: To compare the estimated fetal weight (EFW), abdominal circumference (AC), and femur length (FL), measured on sonographic (US) examinations at 28-34 weeks of gestation to determine the best predictor of macrosomia at birth. METHODS: We retrospectively evaluated 3,857 consecutive, term, singleton pregnancies. The AC, FL, and EFW were compared with birth weights (BW) of >4,000 g and >4,500 g. RESULTS: There was a statistically significant association between the AC and FL and a BW > 4,000 g or >4,500 g (p < 0.001) whether both or either were in the >90th percentile. There was no statistically significant association between an EFW in the >90th percentile and either BW cutoff. An AC in the >90th percentile alone was the best predictor for macrosomia at birth, with sensitivity, specificity, and positive and negative predictive values of 75%, 74%, 24%, and 96%, respectively (95% confidence intervals [CI]: 73-76%, 73-76%, 23-26%, and 96-97%, respectively), for a BW > 4,000 g. When an AC in the >90th percentile was used to predict a BW > 4,500 g, the sensitivity improved to 88%, but the positive predictive value fell to 5%. Receiver operating characteristic curves comparing the distributions of stratified AC values for BW cutoffs of 4,000 and 4,500 g found the highest areas under the curve of 0.80 (95% CI: 0.77-0.82) and 0.87 (95% CI: 0.83-0.90), respectively. CONCLUSIONS: An AC in the >90th percentile at 28-34 weeks' gestation is the best sonographic predictor of macrosomia at birth. © 2014 Wiley Periodicals, Inc. J Clin Ultrasound 43:243-248, 2015.

Accuracy of prenatal diagnosis of isolated aqueductal stenosis.

OBJECTIVE: The objective of this article is to determine the success rate of prenatally diagnosed isolated aqueductal stenosis (AS) as a first step in an evidence-based reassessment of ventriculoamniotic shunting for isolated AS. METHODS: Cases of ventriculomegaly at Magee-Womens Hospital between 2006 and 2013 were ascertained. AS was suspected when prenatal ultrasound and magnetic resonance imaging (MRI) demonstrated signs of pressure hydrocephalus. The prenatal diagnosis generated by ultrasound and MRI was compared with the postnatal diagnosis based upon neonatal neuroimaging. RESULTS: The initial query of the Magee-Womens Hospital database resulted in 370 cases of ventriculomegaly. After exclusion for associated central nervous system malformations, 110 cases of severe ventriculomegaly remained. The imaging studies on each fetus were reviewed, and cases of prenatally diagnosed AS were identified. The median gestational age of the ultrasound diagnosis and prenatal MRI was 23 weeks 3 days and 33 weeks 3 days, respectively. All cases of prenatally suspected isolated AS (six of six) and cases of AS with other associated central nervous system anomalies (six of six) were correctly identified. CONCLUSION: An accurate prenatal diagnosis of isolated fetal AS is possible. This is an important first step in an evidence-based reassessment of ventriculoamniotic shunting for isolated AS. © 2014 John Wiley & Sons, Ltd.

Prenatal midtrimester fetal long bone measurements and the prediction of small-for-gestational-age fetuses at term.

OBJECTIVE: To determine if the length of fetal long bones (LB) at mid-trimester ultrasound is predictive of small-for-gestational-age (SGA) newborns at term delivery. METHODS: Retrospective evaluation of 6,781 women between 18 and 24 weeks' gestation at Magee-Womens Hospital (MWH). Gestational age (GA) was confirmed by first- or second-trimester ultrasound and patient's last menstrual period. Data were accrued from the institutional database at MWH. LB measurements were normalized to GA at the time of the ultrasound. The ratio was correlated with the probability of delivering an SGA newborn at term. RESULTS: In all, 583 women were identified with an SGA newborn (8.6%). LB-to-GA ratios were associated with the probability of delivering an SGA newborn at term (p < 0.001). There was no single LB that proved to be superior in predicting an SGA newborn. CONCLUSION: There is a significant association between LB-to-GA ratio at midtrimester and the probability of SGA at term.

Endometrial thickness and risk of breast and endometrial carcinomas in the prostate, lung, colorectal and ovarian cancer screening trial.

Postmenopausal women with higher circulating estrogen levels are at increased risk of developing breast and endometrial carcinomas. In the endometrium, excess estrogen relative to progesterone produces a net proliferative stimulus, which may result in endometrial thickening. Therefore, the hypothesis that endometrial thickness is a biological marker of excess estrogen stimulation that is associated with risk of breast and endometrial carcinomas was tested. Endometrial thickness was measured in 1,272 postmenopausal women, aged 55-74 years, who underwent transvaginal ultrasound (TVU) screening as part of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. Serial endometrial thickness measurements were available for a subset of women at 1 year (n = 1,018), 2 years (n = 869) and 3 years (n = 641) after baseline. The associations between endometrial thickness and breast (n = 91) and endometrial (n = 14) carcinoma were evaluated by estimating relative risks (RRs) and 95% confidence intervals (CIs) using Cox proportional hazards regression with age as the time metric. Models incorporating baseline endometrial thickness and as a time-varying covariate using all measurements were examined. Median follow-up among study participants was 12.5 years (range: 0.3-13.8 years). Compared to baseline endometrial thickness of 1.0-2.99 mm, women with baseline endometrial thickness greater than or equal to 5.0 mm had an increased risk of breast (RR = 2.00, 95% CI = 1.15-3.48) and endometrial (RR = 5.02, 95% CI = 0.96-26.36) carcinomas in models adjusted for menopausal hormone use and BMI. These data suggest that increased endometrial thickness as assessed by TVU was associated with increased risk of breast and endometrial carcinomas.

Timing of ultrasound in pregnancy--how often? At what intervals?

The second trimester fetal anatomic survey has continued to evolve over the past 27 years. This review will summarize the changes in the anatomic survey that have occurred and provide recommendations that serve to improve compliance with the components of the survey. In order to provide clarity and direction, the goals and limitations of the second trimester fetal anatomic survey should be defined. The visualization rate of specific fetal anatomic structures can be increased by specifying acceptable, alternative views. A single follow-up examination within 2-4 weeks of a fetal anatomic survey or before 22 weeks' gestation should be offered when specific components of the fetal anatomic survey cannot be visualized. The fetal anomalies that the anatomic survey seeks to identify should be defined along with an acceptable detection rate.

Longitudinal assessment of amniotic fluid volume in monoamniotic twin gestations.

OBJECTIVE: The aim of this study is to describe normal amniotic fluid volume through gestation in a cohort of normal monoamniotic (MA) twins. METHOD: Our ultrasound database was queried for MA twin gestations from 2004 to 2011. Monochorionic twin pregnancies mimicking MA gestations, such as twin-twin transfusion syndrome, were excluded. Complicated MA gestations and higher-order multifetal gestations involving an MA pair were excluded. Thirty subjects were followed with serial amniotic fluid index (AFI) measurements from 15 to 32 weeks gestation. Using each AFI measurement as a unique data point, a quadratic regression model and a multi-level growth model were developed against gestational age (GA), providing a predicted AFI at each completed week, with a 95% confidence interval. RESULTS: The quadratic regression least squares and multi-level growth models yielded the same curve comparing the AFI to the GA. Figure 1 depicts the model with the 95% confidence interval for normal amniotic fluid volume by GA for normal MA twins. Table 2 shows the 5th, 50th, and 95th percentiles for AFI by week from 15 to 32 weeks. CONCLUSION: We have generated normative data for amniotic fluid volume across gestation in uncomplicated MA twins. This can be used as a reference when managing MA pregnancies.

Risk of morbid perinatal outcomes in small-for-gestational-age pregnancies: customized compared with conventional standards of fetal growth.

OBJECTIVE: To estimate and compare the risk of morbid perinatal outcomes in pregnancies identified as small for gestational age (SGA) with customized compared with conventional standards of fetal growth. METHODS: Ultrasound-derived estimates of fetal weight were used to generate a fetal growth trajectory (N=7,510). The gestational age at delivery and pathologic and physiologic variables from 5,072 pregnancies were used to calculate a customized threshold for SGA. In a separate analysis of 32,070 pregnancies, rates of morbid outcomes were compared in participants classified as SGA according to a population-based birth weight standard only (SGApop only), a customized standard only (SGAcust only), and both methods (SGAboth). RESULTS: Eight-hundred seventy-five (2.7%) participants were SGApop only, 1,970 (6.1%) participants were SGAboth, and 609 (1.9%) participants were SGAcust only. The odds ratios of neonatal death in SGApop only and SGAcust only pregnancies were 1.78 (95% confidence interval [CI] 0.2-13.1) and 54.6 (95% CI 29.0-102.8), respectively. Rates of prematurity in the SGApop only and SGAcust only cohorts were 4.8% and 64.5%, respectively. After adjustment for the effect of prematurity, odds ratios of neonatal death in the SGApop only and SGAcust only cohorts were 4.8 (95% CI 0.6-37.0) and 2.9 (95% CI 1.4-6.1), respectively. CONCLUSION: After adjustment for confounding stemming from premature delivery, there is little difference in the risk of adverse outcomes between SGAcust only and SGApop only participants. Adoption of customized fetal growth standards into clinical practice may not improve the ability to identify pregnancies with increased risk of perinatal morbidity.

Diagnostic test characteristics of placental weight in the prediction of small-for-gestational-age neonates.

OBJECTIVE: To assess the diagnostic test characteristics of placental weight as a clinical predictor of small-for-gestational-age (SGA) neonates. STUDY DESIGN: Placentas were weighed at 45,846 deliveries. Predictive values and likelihood ratios (LRs) were calculated assessing placental weight (lowest tertile vs. top 2 or mid/high tertiles) as a predictor of SGA both overall and by maternal age, gestational age, maternal weight, reported early pregnancy smoking, race, neonatal sex and parity. RESULTS: Although the positive predictive value (PPV) of low placental weight was poor (0.19), the negative predictive value (NPV) was high (0.97). Both NPV and LR- were powerfully predictive in women at earlier gestational ages. At gestational ages <32 weeks, LR-was 0.11, showing that among women with mid/high placental weight, the proportion with SGA (false negative) was about 1/10 that without SGA (true negative). CONCLUSION: Placental weight in the mid or upper tertile has strong NPV and LR- for delivery of an SGA neonate. Further study of the value of placental size in prediction of SGA is warranted.

Twin pregnancy with a chimeric androgenetic and biparental placenta in one twin displaying placental mesenchymal dysplasia phenotype.

OBJECTIVES: The aim was to report an unusual trizygotic pregnancy that resulted in live-born twins. The placenta of one twin had placental mesenchymal dysplasia (PMD), which resulted from a chimeric fusion of an androgenetic zygote and a normal biparental zygote. The literature review was summarized. METHODS: The case was first detected by prenatal ultrasound, and was then followed by a histologic and detailed genetic investigation. The literature on PMD, complete hydatidiform moles (CHMs), and placental mosaicism and chimerism was also reviewed. RESULTS: One placenta of a twin pregnancy was noted to be diffusely cystic and enlarged. The macroscopic and microscopic findings were consistent with the diagnosis of PMD; however, genetic findings confirmed confined placental chimerism involving a normal biparental 46,XY male conceptus and an androgenetic 46,XX complete hydatidiform mole. CONCLUSIONS: This case represents a rare placental abnormality, PMD, which may have a diverse etiology. Therefore, detailed histologic and genetic analysis were performed for an accurate diagnosis.

Transvaginal ultrasound measurement of endometrial thickness as a biomarker for estrogen exposure.

OBJECTIVE: In clinical settings, transvaginal ultrasound has been used to evaluate abnormal vaginal bleeding. Because the endometrium responds to estrogens, endometrial thickness may constitute a biomarker of estrogen status in postmenopausal women. This study aimed to validate the transvaginal ultrasonographic measurement of endometrial thickness as an estrogen biomarker in asymptomatic, postmenopausal women by demonstrating an association between endometrial thickness and risk factors known to be associated with estrogen exposure. METHOD: Endometrial thickness was measured in 1,271 women ages 55 to 74 years who underwent transvaginal ultrasound screening as part of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial. A questionnaire, completed before screening, provided risk factor information, including reproductive and hormone use histories. RESULTS: Endometrial thickness measurements ranged from 1 to 32 mm (median 3.0 mm). The frequencies of thicker endometrium (> or =3.0 mm), according to body mass index (BMI) quartile, were 55.2%, 66.1%, 69.7%, and 76.7% (P < 0.0001). The frequencies of thicker endometrium were 57.8%, 58.3%, and 82.6% among never users, ex-users, and current users of hormone replacement therapy (HRT), respectively (P < 0.0001). Other factors associated with thicker endometrium included age, marital status, history of uterine fibroids, years since menopause, and history of hypertension. Statistically significant associations were not seen in analyses limited to current HRT users (n = 461). In multiple variable analysis (R2 = 0.08), current HRT use (P < 0.0001) and higher BMI (P < 0.0001) were independently associated with thicker endometrium. CONCLUSION: In postmenopausal women, factors reflecting exogenous (current HRT use) and endogenous (BMI) estrogen exposure were associated with increased endometrial thickness as measured during screening transvaginal ultrasound. Practical limitations related to screening transvaginal ultrasound include measurement variability, lack of information regarding type or dose of HRT, and problems of differentiating true endometrial thickening from unrecognized endometrial polyps or fluid accumulations. Constrained by these limitations, these results partially validate a transvaginal ultrasound measurement of endometrial thickness as a potential biomarker related to estrogen status.

First-trimester screening for trisomies 21 and 18.

BACKGROUND: Screening for aneuploid pregnancies is routinely performed after 15 weeks of gestation and has a sensitivity of approximately 65 percent, with a false positive rate of 5 percent. First-trimester markers of aneuploidy have been developed, but their use in combination has not been adequately evaluated in clinical practice. METHODS: We conducted a multicenter study of screening for trisomies 21 and 18 among patients with pregnancies between 74 and 97 days of gestation, based on maternal age, maternal levels of free beta human chorionic gonadotropin and pregnancy-associated plasma protein A, and ultrasonographic measurement of fetal nuchal translucency. A screening result was considered to be positive for trisomy 21 if the calculated risk was at least 1 in 270 pregnancies and positive for trisomy 18 if the risk was at least 1 in 150. RESULTS: Screening was completed in 8514 patients with singleton pregnancies. This approach to screening identified 85.2 percent of the 61 cases of Down's syndrome (95 percent confidence interval, 73.8 to 93.0), with a false positive rate of 9.4 percent (95 percent confidence interval, 8.8 to 10.1). At a false positive rate of 5 percent, the detection rate was 78.7 percent (95 percent confidence interval, 66.3 to 88.1). Screening identified 90.9 percent of the 11 cases of trisomy 18 (95 percent confidence interval, 58.7 to 99.8), with a 2 percent false positive rate. Among women 35 years of age or older, screening identified 89.8 percent of fetuses with trisomy 21, with a false positive rate of 15.2 percent, and 100 percent of fetuses with trisomy 18. CONCLUSIONS: First-trimester screening for trisomies 21 and 18 on the basis of maternal age, maternal levels of free beta human chorionic gonadotropin and pregnancy-associated plasma protein A, and measurement of fetal nuchal translucency has good sensitivity at an acceptable false positive rate.

Sonographic detection of gallbladder duplication: two cases discovered in utero.

OBJECTIVE: To report the in utero diagnosis of a duplicated gallbladder. METHODS: Obstetric sonography was performed at 2 separate referral centers. A comprehensive level 11 examination was performed at each center. RESULTS: In both cases, a duplicated gallbladder was detected in utero without the presence of other anatomic abnormalities. CONCLUSIONS: Gallbladder duplication, although uncommon, should be considered when an additional cystic structure is seen in the right upper quadrant. Recognition of the presence of a duplicated gallbladder, a relatively benign condition, prevents invoking a more serious diagnosis, such as a choledochal or duodenal duplication cyst.