Use of spatiotemporal image correlation at 11-14 weeks' gestation.

OBJECTIVE: To assess prospectively the use of four-dimensional (4D) spatiotemporal image correlation (STIC) in the evaluation of the fetal heart at 11-14 weeks' gestation. METHODS: The study involved offline analysis of 4D-STIC volumes of the fetal heart acquired at 11-14 weeks' gestation in a population at high risk for congenital heart disease (CHD). Regression analysis was used to investigate the effect of gestational age, maternal body mass index, quality of the 4D-STIC volume, use of a transvaginal vs transabdominal probe and use of color Doppler ultrasonography on the ability to visualize separately different heart structures. The accuracy in diagnosing CHD based on early fetal echocardiography (EFE) using 4D-STIC vs conventional two-dimensional (2D) ultrasound was also evaluated. RESULTS: One hundred and thirty-nine fetuses with a total of 243 STIC volumes were included in this study. Regression analysis showed that the ability to visualize different heart structures was correlated with the quality of the acquired 4D-STIC volumes. Independently, the use of a transvaginal approach improved visualization of the four-chamber view, and the use of Doppler improved visualization of the outflow tracts, aortic arch and interventricular septum. Follow-up was available in 121 of the 139 fetuses, of which 27 had a confirmed CHD. A diagnosis based on EFE using 4D-STIC was possible in 130 (93.5%) of the 139 fetuses. Accuracy in diagnosing CHD using 4D-STIC was 88.7%, and the results of 45% of the cases were fully concordant with those of 2D ultrasound or the final follow-up diagnosis. EFE using 2D ultrasound was possible in all fetuses, and accuracy in diagnosing CHD was 94.2%. Five of the seven false-positive or false-negative cases were minor CHD. CONCLUSIONS: In fetuses at 11-14 weeks' gestation, the heart can be evaluated offline using 4D-STIC in a large number of cases, and this evaluation is more successful the higher the quality of the acquired volume. 2D ultrasound remains superior to 4D-STIC at 11-14 weeks, unless volumes of good to high quality can be obtained.

First trimester fetal echocardiography: where are we now?

The detailed study of the fetal cardiac anatomy in the first trimester of pregnancy by means of ultrasound is feasible whether using a transvaginal or a transabdominal approach. There is nowadays enough evidence that ultrasound in the first trimester of pregnancy is a safe procedure provided thermal and mechanical indices are taken into account. The best timing for successful imaging of the four chambers and great arteries in early gestation appears to be between around 13 to 14 weeks rather than 11 to 12 weeks. In experienced hands, first-trimester fetal echocardiography is quite sensitive for the detection of major structural cardiac abnormalities. Besides the nasal bone, markers for first trimester screening of chromosomal abnormalities such as nuchal translucency thickness, the flow in the ductus venosus and the flow through the tricuspid valve constitute also markers for cardiac abnormalities. The finding of an increased nuchal translucency, an abnormal flow in the ductus venosus or a tricuspid regurgitation constitutes an indication for more detailed fetal cardiac assessment. Other indication for a detailed cardiac assessment is the finding of an aberrant right subclavian artery and vascular anomalies. The emerging importance of these markers has caused renewed interest in the early study of the fetal heart.

Postmortem examination of human fetal hearts at or below 20 weeks' gestation: a comparison of high-field MRI at 9.4 T with lower-field MRI magnets and stereomicroscopic autopsy.

OBJECTIVES: To compare the diagnostic usefulness of high-field with low-field magnetic resonance imaging (MRI) and stereomicroscopic autopsy for examination of the heart in fetuses at or under 20 weeks' gestation. METHODS: Prior to invasive stereomicroscopic autopsy, MRI scans at 9.4, 3.0 and 1.5 T were performed on 24 fetuses between 11 and 20 weeks' gestation, including 10 fetuses with cardiac abnormalities. The ability to visualize different heart structures was evaluated according to the different field strength MRI magnets used and gestational age at examination. RESULTS: On 1.5- and 3.0-T MRI, only the heart situs and four-chamber view could be visualized consistently (in 75% or more of cases) when the fetus was beyond 16 weeks' gestation, but other heart structures could not be visualized for fetuses at any gestational age. In contrast, using high-field MRI at 9.4 T, the heart situs, four-chamber view and the outflow tracts could be visualized in all fetuses irrespective of gestational age. Using high-field MRI, the sensitivity for detecting an abnormality of the four-chamber view was 66.7% (95% CI, 30.1-92.1%) with a specificity of 80.0% (95% CI, 51.9-95.4%). For abnormalities of the outflow tracts, sensitivity was 75.0% (95% CI, 20.3-95.9%) and specificity 100.0% (95% CI, 83.3-100.0%). Eight fetuses out of 10 with congenital heart disease (CHD) were classified as having major CHD. High-field MRI at 9.4 T was able to identify seven out of the eight cases of major CHD. CONCLUSION: High-field MRI at 9.4 T seems to be an acceptable alternative approach to invasive stereomicroscopic autopsy for fetuses with CHD at or below 20 weeks' gestation.

Virtual autopsy by computed tomographic angiography of the fetal heart: a feasibility study.

OBJECTIVE: To determine the feasibility of postmortem computed tomographic (pm-CT) angiography for fetal heart evaluation. METHODS: Following termination of pregnancy (TOP) or intrauterine fetal death (IUFD) beyond 18 weeks' gestation, 33 fetuses were examined by pm-CT; in eight contrast medium was injected through the umbilical cord and in 25 contrast medium was injected directly into the heart. Logistic regression analysis was used to investigate the effect on the ability to visualize cardiac structures on pm-CT angiography of gestational age at TOP or delivery following IUFD, the time delay between fetal death and examination, the technique used for contrast-medium injection, the presence of cardiac abnormalities and whether or not there was IUFD. The diagnostic accuracy of pm-CT angiography for the evaluation of fetal cardiac structures was also evaluated. RESULTS: Cardiac anatomy including heart situs, the four-chamber view and great vessels could be visualized on pm-CT angiography in 29 out of 33 fetuses (87.9%). Logistic regression analysis showed that the ability to visualize cardiac structures on pm-CT angiography was positively correlated only with contrast medium injected directly into the heart. Twenty-five out of the 33 fetuses underwent conventional autopsy. There were five cases with suspected major cardiac abnormality at prenatal ultrasound and one with a minor cardiac abnormality. In one of these cases, severe leakage into the pleural cavity did not allow for visualization of any heart structure on pm-CT angiography and in another invasive autopsy was declined. In two of the remaining four cases, the findings on pm-CT angiography and invasive autopsy were in agreement, while in two a ventricular septal defect was found on invasive autopsy but not on pm-CT. None of the 27 cases with normal hearts was falsely classified as abnormal using pm-CT angiography. CONCLUSION: Pm-CT angiography by direct injection into the heart seems to be a feasible method for its evaluation. The extent to which such a technique could be used for the evaluation of congenital heart disease as an alternative to classical postmortem autopsy remains to be determined.

Fetal organ weight estimation by postmortem high-field magnetic resonance imaging before 20 weeks' gestation.

OBJECTIVE: To ascertain whether high-field magnetic resonance imaging (MRI) allows accurate estimation of the weight of various fetal organs at postmortem before 20 weeks' gestation. METHODS: From 23 fetuses at 9-20 weeks, following termination of pregnancy or in-utero fetal death (IUFD), 207 assorted fetal organs were evaluated by high-field MRI at 9.4 T prior to conventional autopsy. Fetal organ density was calculated by correlating volume and weight at autopsy using linear regression analysis, and this was used to estimate fetal organ weight by MRI. The relative error in MRI estimation of organ weight was calculated as follows: (|MRI weight - autopsy weight|/autopsy weight) × 100 (%). Multiple regression analysis was used to investigate the effect on the relative error of MRI organ weight estimates of gestational age at TOP or delivery following IUFD, autopsy weight, fetal organ examined, IUFD and fetal maceration. RESULTS: Of the 207 organs evaluated, 133 (64%) were examined for fetal organ density and 155 (75%) for fetal organ weight. Fifty-two organs were excluded from our analysis; 41 of these were from fetuses with IUFD, with 39 organs macerated. In 32 cases, exclusion was due to an inability to assess the organ both on MRI and on conventional autopsy. Volume and weight at autopsy correlated significantly, following the linear equation: autopsy volume = (0.9947 × autopsy weight) - 4.7556, where autopsy volume is in mm(3) and weight is in mg (r = 0.99, P < 0.001). Overall the mean relative error in the MRI estimation of organ weight was 68%. Multiple regression analysis showed that the relative error in the MRI estimation of organ weight was significantly associated with gestational age at TOP or delivery following IUFD and fetal maceration, but not with autopsy weight, fetal organ examined or IUFD. In the subgroup of non-macerated organs and for fetuses above 14 weeks' gestation, the mean relative error in the MRI estimation of organ weight was 34%. CONCLUSION: In fetuses before 20 weeks' gestation, noninvasive estimation of organ weight is feasible using high-field MRI, but there is a mean overestimation. Limitations of the technique occur mainly in cases of small macerated fetuses before 14 weeks' gestation.

Acceptance, reliability and confidence of diagnosis of fetal and neonatal virtuopsy compared with conventional autopsy: a prospective study.

OBJECTIVES: To compare prospectively maternal acceptance of fetal and neonatal virtuopsy with that of conventional autopsy and to determine the confidence with which magnetic resonance (MR) virtuopsy can be used to diagnose normality/abnormality of various fetal anatomical structures. METHODS: MR and/or computed tomography virtuopsy and conventional autopsy were offered to 96 women (102 fetuses/neonates) following termination of pregnancy (TOP), intrauterine fetal death (IUFD) or neonatal death. Multivariable logistic regression analysis was used to investigate the effect on maternal acceptance of virtuopsy and/or conventional autopsy of the age of the mother, gestational age at TOP or delivery after IUFD, order of pregnancy, parity, religion, type of caregiver obtaining consent and reason for death. When parents consented to both MR virtuopsy and conventional autopsy of fetuses ≥ 20 weeks of gestation or neonates, the confidence with which MR virtuopsy could be used to diagnose normality/abnormality of various anatomical structures was determined on a scale in which conventional autopsy was considered gold standard. On autopsy we classified fetuses/neonates as having either 'normal' or 'abnormal' anatomical structures; these groups were analyzed separately. At virtuopsy, we indicated confidence of diagnosis of normality/abnormality of every anatomical structure in each of these two groups defined at autopsy, using a scale from 0 (definitely abnormal) to 100 (definitely normal). RESULTS: Of the 96 women, 99% (n = 95) consented to virtuopsy and 61.5% (n = 59) to both conventional autopsy and virtuopsy; i.e. 36 (37.5%) consented to virtuopsy alone. Maternal acceptance of conventional autopsy was independently positively related to singleton pregnancy, non-Moslem mother, earlier gestation at TOP or delivery afer IUFD and a maternal-fetal medicine specialist obtaining consent. Thirty-three fetuses ≥ 20 weeks of gestation had both conventional autopsy and MR virtuopsy, of which 19 had a full autopsy including the brain. In fetuses with normal anatomical structures at conventional autopsy, MR virtuopsy was associated with high diagnostic confidence (scores > 80) for the brain, skeleton, thoracic organs except the heart, abdominal organs except the pancreas, ureters, bladder and genitals. In fetuses with abnormal anatomical structures at autopsy, MR virtuopsy detected the anomalies with high confidence (scores < 20) for these same anatomical structures. However, in three cases, virtuopsy diagnosed brain anomalies additional to those observed at conventional autopsy. CONCLUSION: MR virtuopsy is accepted by nearly all mothers while conventional autopsy is accepted by about two-thirds of mothers, in whom refusal depends mainly on factors over which we have no control. Although conventional autopsy remains the gold standard, the high acceptance of virtuopsy makes it an acceptable alternative when the former is declined.

Magnetic resonance imaging in the normal fetal heart and in congenital heart disease.

OBJECTIVE: To evaluate prospectively the feasibility of magnetic resonance imaging (MRI) for assessment of the fetal heart for congenital heart disease (CHD). METHODS: This was a cross-sectional study, including 66 fetuses with a normal heart and 40 with CHD. The fetal heart was examined on MRI using axial steady-state free precession (SSFP) sequences. Regression analysis was used to investigate the effect on the ability to visualize cardiac anatomy of gestational age at examination, maternal body mass index, presence of fetal cardiac abnormality, fetal movements, fetal lie and twinning. The sensitivity and specificity of detecting cardiac defects were calculated. RESULTS: The four-chamber view was visualized in 98.1% of fetuses. The sensitivity of detecting a cardiac defect on the four-chamber view was 88% and the specificity 96%. The ability to visualize the left and right outflow tracts was only influenced by the presence of fetal movements: for the left outflow tract 94.4 vs. 50.0% visualization and for the right outflow tract 92.6 vs. 53.8% visualization without and with fetal movements, respectively. The sensitivity of detecting a cardiac defect of the left outflow tract was 63% and the specificity 100%, while sensitivity and specificity were 59 and 97%, respectively, for the right outflow tract. CONCLUSIONS: Despite the use of SSFP sequences, MRI in the fetal heart remains of limited value. It can only be used as a second-line approach for abnormalities of the four-chamber view suspected at prenatal ultrasound.

Use of a high-frequency linear transducer and MTI filtered color flow mapping in the assessment of fetal heart anatomy at the routine 11 to 13 + 6-week scan: a randomized trial.

OBJECTIVE: To prospectively assess the contribution of a high-frequency linear transducer and of moving target indicator (MTI) filtered color flow mapping in the visualization of cardiac fetal anatomy at the routine 11 to 13 + 6-week scan. METHODS: This was a cross-sectional prospective study, including 300 singleton fetuses at 11 to 13 + 6 weeks' gestation. Patients were randomized into four groups and a detailed fetal cardiac examination was conducted transabdominally using either a conventional curvilinear transducer, a conventional curvilinear transducer and MTI filtered color flow mapping, a high-frequency linear transducer or a high-frequency linear transducer and MTI filtered color flow mapping. Regression analysis was used to investigate the effect on the ability to visualize different cardiac structures of the following parameters: gestational age at ultrasound examination; fetal crown-rump length (CRL); maternal body mass index (BMI); transducer-heart distance; the technique used at ultrasound; and the position of the placenta. RESULTS: The four-chamber view was visualized in 89.0% of fetuses and regression analysis showed this rate was correlated with CRL and the use of MTI filtered color flow mapping during ultrasonography, and inversely correlated with BMI and transducer-heart distance. Use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the four-chamber view in 97.3% of fetuses, while this was only possible in 84.0% of fetuses using a high-frequency linear transducer. The left and right outflow tracts were visualized in 62.3 and 57.7% of fetuses, respectively. Regression analysis showed that the ability to visualize the left or the right outflow tract was correlated with the use of MTI filtered color flow mapping during scanning and was inversely correlated with transducer-heart distance. The use of a conventional curvilinear transducer and MTI filtered color flow mapping allowed visualization of the left and right outflow tracts in 96.0 and 97.3% of fetuses, respectively, while this was only possible in 37.3 and 26.7% of fetuses using a high-frequency linear transducer. CONCLUSIONS: During the routine 11 to 13 + 6-week scan, the use of MTI filtered color flow mapping but not of a high-frequency linear transducer, improves visualization of cardiac anatomy.

Contribution of three-dimensional computed tomography in the assessment of fetal skeletal dysplasia.

OBJECTIVE: To compare the diagnostic accuracy of two-dimensional (2D) ultrasound and three-dimensional (3D) computed tomography (CT) for the diagnosis of fetal skeletal anomalies. METHODS: Eleven pregnant women underwent 2D ultrasound and 3D-CT. Ten fetuses presented skeletal anomalies on 2D ultrasound and one fetus had a normal ultrasound exam but a familial history of osteopetrosis. We compared retrospectively the diagnoses established on 2D ultrasound and 3D-CT with the neonatal and/or postmortem work-up, which were used as the gold standard. RESULTS: 2D ultrasound provided the correct diagnosis in only two of the 11 cases. CT yielded the correct diagnosis in eight; in six of these, 2D ultrasound had been inconclusive. 3D-CT was more accurate than was 2D ultrasound in visualizing vertebral anomalies (abnormal shape of the vertebral bodies, abnormal interpedicular distance), pelvic bone malformations (delayed ossification of the pubic bones, abnormal acetabular shape) and enlarged metaphysis or synostoses in long bones. In three cases, neither 2D ultrasound nor CT provided the correct diagnosis. CONCLUSION: In this series, which included a variety of skeletal dysplasias, 3D-CT had a better diagnostic yield than did 2D ultrasound. Both imaging techniques are useful in the management of fetal dysplasia; 2D ultrasound is a useful screening test and 3D-CT is a valuable complementary diagnostic tool.

Evolution of fetal ultrasonography.

The authors wish to highlight the evolution that has occurred in fetal ultrasound in recent years. A first significant evolution lies in the increasing contribution of first trimester ultrasound for the detection of fetal anomalies. Malformations of several organs and systems have been diagnosed during the first trimester. Furthermore the systematic measurement of the fetal neck translucency has led to increasing rate of detection of aneuploidies and heart malformations. For several years now, three-dimensional (3D) and 4D ultrasound (US) have been used as a complementary tool to 2D US for the evaluation of fetal morphology. This brings an improved morphologic assessment of the fetus. Applications of the techniques are increasing, especially for the fetal face, heart and extremities. The third field where fetal US is continuously providing important information is the knowledge of the natural history of diseases. This has brought significant improvement in the postnatal management of several diseases, especially urinary tract dilatation and broncho-pulmonary malformation.

Left and right lung volumes in fetuses with diaphragmatic hernia.

OBJECTIVE: To compare the volume of the ipsilateral and contralateral lungs in fetuses with congenital diaphragmatic hernia (CDH). METHODS: Left and right lung volumes were measured using three-dimensional (3D) ultrasonography in 42 fetuses with CDH at median 26 (range, 20-32) weeks of gestation. Each value was then expressed as a difference, in standard deviations, from the normal mean for gestation, previously established from the study of 650 normal fetuses at 12-32 weeks (Z-score). The Mann-Whitney U-test was used to determine the significance of the differences between the measurements in fetuses with CDH and normal fetuses and between the ipsilateral and contralateral lungs in fetuses with left- and right-sided CDH. RESULTS: There were 34 fetuses with left-sided CDH and eight with right-sided CDH. In CDH both the ipsilateral and contralateral lung volumes were substantially lower than in normal fetuses. In left CDH the left lung volume was 4.03 (median; range, 3.11-4.78) SDs below the normal mean for gestation, and the respective values for the right lung were 3.04 (median; range, 1.78-4.31) SDs (P < 0.001 for both). In right CDH, the left lung volume was 2.91 (median; range, 1.62-4.07) SDs below the normal mean for gestation and the respective values for the right lung were 4.35 (median; range, 3.07-4.99) SDs (P < 0.001 for both). In both left and right diaphragmatic hernia the deficit in the volume of the ipsilateral lung was significantly greater than the deficit in the contralateral lung. CONCLUSIONS: In fetuses with CDH both the ipsilateral and contralateral lung volumes are substantially lower than in normal fetuses.

Dismorfología facial fetal a través de la ecografía 3D / Fetal facial dysmorphology by 3D echography

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Generation of null alleles for the functional analysis of six genes from the right arm of Saccharomyces cerevisiae chromosome II.

Using PCR-ligated long flanking homology cassettes, null alleles of six open reading frames (ORFs) from chromosome II have been created in Saccharomyces cerevisiae. Deletants were constructed in three genetic backgrounds: FY1679, W303 and CEN.PK2. Tetrad analysis of heterozygous deletants revealed that none of the ORFs is essential for vegetative growth. Basic phenotypic analysis of haploid deletants showed that deletion of the YBR283c ORF causes a slight growth defect at 30 degrees C and 37 degrees C on glycerol-complete, glucose-complete, and glucose-minimal media only in the FY1679 and W303 backgrounds. Transformation of these deletants with the corresponding cognate gene in a centromeric plasmid complements the defects. Deletion of the YBR287w ORF leads to poor growth on glucose-minimal medium at 15 degrees C in the FY 1679 background. None of the six ORFs seems to be involved in mating or sporulation.

Molecular analysis of Chs3p participation in chitin synthase III activity.

Chitin is a minor but essential component of the cell wall of Saccharomyces cerevisiae, with functions in septum formation in the vegetative life cycle and also in conjugation and spore cell-wall synthesis in the sexual cycle. Of the three chitin synthases present in yeast, chitin synthase III (CSIII) is responsible for the synthesis of most of the chitin found in the cell, including a chitin ring at early budding, chitin interspersed in the cell wall, and chitin laid down during the sexual cycle. We have tagged Chs3p, the putative catalytic subunit of CSIII, with the immunoreactive epitope of influenza virus hemagglutinin to follow expression of the protein. Little correlation was found between the levels of transcription and translation of Chs3p and in vivo function, supporting our previous conclusion that regulation of CSIII occurs at the posttranslational level. To identify possible regions of the protein involved in catalysis or regulation, mutations were generated in the QRRRW 'signature sequence' of chitin synthases. Arginine residue mutations in Chs3p, and in Chs1p and Chs2p, resulted in a loss of both function in vivo and enzymatic activity. Mutations in a serine residue adjacent to glutamine in Chs3p caused loss of function in vivo with a moderate decrease in CSIII activity, suggesting a regulatory role for the serine residue in chitin biosynthesis. Several truncations in the unique hydrophilic carboxy-terminal region of Chs3p identified a sequence of about 25 amino acids that is required for both function and in vitro activity. Since this region is not present in Chs1 or Chs2, it may be involved in the specific regulation of CSIII.

Characterization of CHS4 (CAL2), a gene of Saccharomyces cerevisiae involved in chitin biosynthesis and allelic to SKT5 and CSD4.

We have cloned CHS4, a gene that complements the resistance to Calcofluor of the Saccharomyces cerevisiae cal2 mutant. We show that CHS4 is allelic to the previously described SKT5 and CSD4 genes. CHS4 encodes a 696 amino acids protein with no potential transmembrane domain. chs4-null mutants are resistant to Calcofluor white and exhibit a considerable reduction in cell wall chitin and in chitin synthase III (CSIII) activity. Biochemical characterization of chitin synthase III from these null mutants indicates that the defect is due to a reduced V(max) of the enzyme. This defect can be overcome in vitro by trypsin treatment of the membrane preparations. Chs4p does not act as a transcriptional or translational regulator of CHS3, the gene coding for the catalytic subunit of CSIII activity, and we therefore propose that Chs4p would be an essential component of the CSIII complex, acting as a post-translational regulator of this activity. In addition to the chitin defect, the chs4 mutant shows a severe defect in mating.

[Perinatal transmission of the human immunodeficiency virus in the second trimester of pregnancy]. / Transmisión perinatal del virus de la inmunodeficiencia humana en el segundo trimestre de gestación.

BACKGROUND: A prospective study was carried out in pregnant women seropositive for HIV-1 who wished to interrupt the pregnancy with the aim of detecting the specific sequences of DNA in fetal blood obtained by cordocentesis during the second trimester of pregnancy. METHODS: The samples of fetal blood were obtained by cordocentesis with the Kleihauer's test being performed to discard contamination of maternal blood. In both maternal and fetal blood the HIV-1 antibodies, Western blot, p-24 antigen and hematologic parameters were determined. The DNA-HIV-1 sequences were determined by double PCR. Fifteen pregnant women were included in the study with one patient being excluded upon detection of contamination of fetal blood with maternal blood. In 8 cases the study could not be completed due to lack of material. RESULTS: The specific sequences of DNA of HIV were detected in the six pregnant women and in three of the six fetuses studied. The anti-HIV-1 antibodies were present in all the samples of maternal and fetal blood with the bands of antibodies by Western blot being identical for each mother-fetus pair. No differences were observed in the mother-fetus pair. No differences were observed in the hematologic parameters or in the lymphocytic subpopulations among the fetuses with positive DNA sequences and those which demonstrated a negative result. CONCLUSIONS: These preliminary results suggest that fetal infection by HIV-1 may be produced during pregnancy. Cordocentesis may be useful for determining the fetus which are infected in utero although this must be restricted to patients who wish to terminate the pregnancy due to the potential risk of infecting a previously healthy fetus.