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D H Pretorius

Publications and source records attributed to D H Pretorius.

At least 55 records · Page 3Linked to original sources
PubMed1996

Three dimensional ultrasound: display modalities in the fetal spine and thorax.

PURPOSE: To evaluate the display modalities of three dimensional ultrasound (3D US) in the prenatal assessment of the fetal spine and thorax. METHOD: Twenty prenatal spine examinations (mean gestational age: 21 weeks, 15 normal findings, five pathological cases) were performed with a commercially available 3D US device. The visualization of fetal spine and rib anatomy and pathology by 3D US display was evaluated using various rendering methods and the optimal method was determined in regard to comprehensive diagnostic display. RESULTS: Demonstration of continuity of both the spine and the ribs could be achieved by 3D US. Visualization of clavicles, scapula and iliac bone was possible on rendered images. CONCLUSION: 3D US offers an additional diagnostic tool for prenatal assessment of the fetal spine and ribs; it provides a continuous demonstration of curved or tortuous structures in the rendered image. It improves comprehension of complex anatomy by providing a simultaneous display of all orthogonal sectional planes.

Female↗
PubMed1996

Three-dimensional ultrasound: accuracy of distance and volume measurements.

The aim of this study was to evaluate the accuracy of three-dimensional ultrasound distance and volume measurements using a commercially available three-dimensional ultrasound scanner. Sixty-two distance measurements were performed twice on an ultrasound tissue-mimicking phantom located in a water bath. Three-dimensional ultrasound distance measurements were compared to the actual distance. Volume measurements were made in a water bath with 21 balloons of various shapes ranging in volume from 20 ml to 490 ml. Three-dimensional ultrasound volume measurements were compared to actual balloon volumes and to conventional two-dimensional ultrasound volume calculations. The mean absolute error in three-dimensional ultrasound distance measurements was 1.0 +/- 0.8% (range, -2.3 to +1.9%) in the plane of acquisition and 1.0 +/- 0.6% (range, -2.0 to -0.2%) for planes with other orientations. Three-dimensional ultrasound volume measurements showed a mean absolute error of 6.4 +/- 4.4% (range, -6.0% to +15.5%), which was considerably better than two-dimensional ultrasound volume estimates having a mean absolute error of 12.6 +/- 8.7% (range, -27.5% to +39.2%). Volume measurements using two-dimensional ultrasound methods were much less accurate than three-dimensional ultrasound methods for irregularly shaped objects. In conclusion, our data show that three-dimensional ultrasound measurements of distance and volume are sufficiently accurate to use clinically.

Diagnostic Imaging↗
PubMed1996

Ultrasonography.

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Humans↗
PubMed1996

Placental cord insertion visualization with prenatal ultrasonography.

Color Doppler and gray scale sonography can be used prenatally to identify the location of the cord insertion into the placenta. The purposes of this paper were to (1) relate sonographic identification of placental cord insertion with placental pathology; (2) evaluate the possibility that a marginal cord insertion may evolve into a velamentous cord insertion; and (3) determine the frequency and factors affecting sonographic visualization of cord insertion. Our results show that the sonographic assessment of cord insertion correlated with the pathologic outcome in 83% (106 of 128) of singleton pregnancies and at least one of the fetuses in 72% (8 of 11) of twin or triplet pregnancies. Although the sensitivity for identification of an abnormal cord insertion was low (42%), the specificity was high (95%). Our data suggest that marginal cord insertion evolved into velamentous cord insertion in one singleton and one twin. Our results showed that cord insertion was visualized in 54% of fetuses scanned in a routine clinical practice. Cord insertion visualization was possible at all gestational ages, although it was more difficult at later gestational ages. In conclusion, this study provides evidence that (1) ultrasonography (either gray scale or color Doppler) is useful in identifying normal, marginal, and velamentous cord insertion; (2) marginal cord insertion may evolve into velamentous cord insertion as pregnancy progresses; (3) in clinical practice the cord insertion site was visualized in just over half of the cases, and (4) prenatal identification of marginal and velamentous cord insertion potentially may be useful for planning obstetrical management.

Female↗
PubMed1996

In vivo three-dimensional sonographic measurement of organ volume: validation in the urinary bladder.

The purpose of this study was to assess the accuracy of in vivo measurement of organ volume using 3DUS and compare the results to 2D sonographic methods using the urinary bladder as the target organ and voided urine volume for validation. Fifty normal volunteers were studied. 2D volume measurements were based on length, width, and depth data and assumed a regular geometric model. 3D volume measurements were based on masked slices with the voxels integrated over the entire bladder. Voided urine volumes ranged from 35 ml to 701 ml. Residual urine volume was present in 48% of the subjects and ranged from 1% to 14% of the voided volume. 2D volume estimates for all 50 subjects had a mean absolute value of the error of 27.5% +/- 17.8%. 3D volume measurements had a mean absolute value of the error of 4.3% +/- 3.7% (transverse) and 5.6% +/- 3.8% (longitudinal). 3DUS provided more accurate volume measurements than 2DUS, particularly for irregularly shaped organs.

Adolescent↗
PubMed1996

Three-dimensional echocardiographic evaluation of fetal heart anatomy and function: acquisition, analysis, and display.

The purpose of this work was to assess the functional dynamics and anatomy of the cardiac chambers and great vessels in the fetus (18 to 36 weeks) using in utero three-dimensional ultrasonographic imaging. Fifteen patients were studied using conventional two-dimensional sonographic equipment incorporating a position sensor attached to the transducer and a graphics workstation. Sonographic image data were acquired at 30 images per second and required less than 30 seconds per data set. Fetal heart rate and time in the cardiac cycle were determined and used to synchronize image data for reprojection into a volume at the appropriate part of the cardiac cycle. Volume data were analyzed, rendered, and displayed interactively. Three-dimensional sonographic volume data demonstrated fetal cardiac anatomy from multiple orientations and showed the myocardium, valves, ventricles, and atria clearly. The images showed good correlation with currently available embryologic-anatomic-pathologic data. Dynamic and spatial relationships among chambers, valves, and great vessels were readily appreciated. Three-dimensional sonographic imaging of the fetal heart provides both anatomic and functional information regarding the valves, myocardium, great vessels, and chamber dynamics. Interactive three-dimensional cinegraphic display enhances visualization of cardiac anatomy, which can be difficult to appreciate with two-dimensional methods. The methods presented in this work demonstrate the feasibility of three-dimensional fetal echocardiography.

Aorta↗
PubMed1995

Cephalocele detection in utero: sonographic and clinical features.

Sonographic and clinical features of 26 fetal cephaloceles were reviewed retrospectively. The most frequent reason for referral was elevated maternal serum alpha-fetoprotein levels. The smallest lesion identified was 0.4 x 0.5 cm (frontal, at 20 weeks); the largest was 9.0 x 10.0 cm (frontal, at 27 weeks). Twenty-four of 26 cephaloceles were detected on prenatal ultrasound examination; in 13 of these, more than 50% of the intracranial contents were exteriorized. Fifteen of 24 cephaloceles detected prenatally had a sulcal pattern (identified between 16 and 36 weeks' gestation); five were solid without a sulcal pattern (identified between 13 and 21 weeks' gestation), three were cystic, and one underwent a change in appearance from solid at 21 weeks to cystic at 26 weeks. Other cranial features were evaluated and included visible skull defect, seen in 23/24 (96%), ventriculomegaly, in 6/26 (23%); microcephaly, in 12/24 (50%); beaked tectal plate, in 6/16 (38%); and flattened basiocciput, in 9/24 (38%). Of the 26 cases, 14 had normal amniotic fluid volume, five had oligohydramnios and seven had polyhydramnios. Fetuses with oligohydramnios had the highest incidence of concurrent fetal abnormalities; four of five fetuses (80%) with oligohydramnios had additional structural abnormalities. In the overall population, a very high incidence of other abnormalities was found; 17/26 (65%) cases showed additional abnormalities, some of which were not detected by ultrasound. Five fetuses had Meckel-Gruber syndrome and three had amniotic band syndrome. Only one of the 18 karyotypes obtained was abnormal (trisomy 18). Survival was very poor; only two of the eight who survived until birth are currently living.

Abnormalities, Multiple↗
PubMed1995

Three-dimensional ultrasound.

The papers in this issue show that the feasibility of three-dimensional ultrasound methods in the clinical setting using commercially available equipment is nearby. Their results demonstrate some of the advantages compared to two-dimensional ultrasound and other diagnostic modalities, including reduced scanning times that will offer more cost-effective use of equipment and sonographer time. Other benefits of three-dimensional ultrasound include allowing the physician: to evaluate arbitrary planes not available with two-dimensional ultrasound due to patient body habitus; to measure organ dimensions and volumes; to obtain anatomic and blood flow information; to improve assessment of complex anatomic anomalies; to confirm normalcy; to standardized the ultrasound exam procedures; to enhance the understanding of physicians in primary care facilities and communicate volume data over networks for consultation at tertiary facilities. Standardization of the ultrasound examination protocols can lead to uniformly high-quality examinations and decreased health care costs. Ultimately, three-dimensional ultrasound imaging will make it easier for primary care physicians to understand complex patient anatomy. Tertiary care physicians specializing in ultrasound can further enhance the quality of patient care by using high-speed computer networks to review volume or dynamic data at specialization centers with primary care physicians. Access to volume data at specialization centers affords more sophisticated analysis and review, further augmenting patient diagnosis and treatment and reducing health care costs.

Congenital Abnormalities↗
PubMed1995

Ultrasonography.

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Humans↗
PubMed1995

Sonography of the fetal spine: technique, imaging findings, and clinical implications.

Sonographic evaluation of the fetal spine is an essential part of any fetal survey, and it is included in the current American Institute of Ultrasound in Medicine/American College of Radiology and American College of Obstetrics and Gynecology guidelines for obstetric sonography [1, 2]. In this paper, we review the current knowledge of anatomy of the normal fetal spine and the sonographic findings associated with spinal anomalies, with special emphasis on neural tube defects. Important cranial clues to a spine abnormality initially may be more obvious at sonography than the spine abnormality itself, and the general significance of these clues is provided. The expanding role of prenatal maternal serum and amniotic fluid testing is explored, as are the benefits and modifications these bring to sonographic evaluations. Finally, the potential benefits of the rapidly advancing technology of three-dimensional sonography are introduced.

Female↗
PubMed1995

Visualization of the fetal thoracic skeleton with three-dimensional sonography: a preliminary report.

OBJECTIVE: Evaluation of the complete anatomy of the thoracic skeleton in the developing fetus often is difficult with conventional two-dimensional (2D) sonography because of the curvature of the bones. The purpose of the present work was to assess the ability of three-dimensional (3D) sonography to provide a more complete representation of the fetal thoracic skeleton than available with 2D sonography. SUBJECTS AND METHODS: We performed 3D sonographic imaging in eight healthy volunteer pregnant women after obtaining informed consent. Conventional 2D sonographic equipment was adapted to obtain 3D data and to produce volume-rendered images. The 3D sonographic images of the bony spine and thorax were evaluated for clarity with which the vertebral bodies, ribs, scapulae, clavicles, and overall thoracic anatomy were depicted. RESULTS: The vertebral bodies, spine, and ribs were identifiable on 3D sonograms, which clearly showed the structural continuity of the spine and ribs in all fetuses. Zoomed images of subregions of the spine were useful for showing details of the vertebrae. Stereo glasses and rotation of the volume data proved useful in appreciating the spatial relationships of the spine and rib cage. CONCLUSION: Three-dimensional sonography provides additional information about the fetal thoracic skeleton to that furnished by 2D sonography by presenting the thorax as a coherent structure rather than as a series of cross-sectional slices.

Bone and Bones↗
PubMed1995

Evaluation of normal and abnormal lips in fetuses: comparison between three- and two-dimensional sonography.

OBJECTIVE: The purpose of this study was to determine if three-dimensional (3D) sonography could improve prenatal evaluation of fetal lips in comparison with conventional two-dimensional (2D) sonography. MATERIALS AND METHODS: Sixty-one high-risk pregnant women and 10 low-risk pregnant women were examined with conventional 2D sonography followed by 3D sonography with a volume transducer. The ability to visualize cleft lips and normal lips was compared between the two techniques. RESULTS: Of the 71 fetuses studied, faces were seen in 68 and not seen in three by either 2D or 3D sonography. Abnormal lips were seen in five fetuses on both 2D and 3D sonograms. Of the remaining fetuses, 3D sonography was able to confirm the presence of a normal lip in 92% (58/63) compared with 76% (48/63) with 2D sonography. In the subgroup of fetuses less than 24 weeks' estimated gestational age, 3D sonography confirmed a normal lip in 93% (38/41) of fetuses as compared with 68% (28/41) for 2D sonography. There was no difference between 3D and 2D in the subgroup of fetuses older than 24 weeks. One false-positive finding of cleft lip was observed at 36 weeks' gestational age with the rendered surface display on 3D sonography, whereas the 3D planar views of the same volume showed the lips to be normal. CONCLUSION: 3D sonography was able to confirm the presence of normal lips more frequently than did 2D sonography in fetuses less than 24 weeks' gestational age. Abnormal lips were seen on both 2D and 3D sonograms; however, 3D images of cleft lip were easier to understand for both the family and clinical colleagues.

Cleft Lip↗
PubMed1995

Distance and volume measurement using three-dimensional ultrasonography.

The purpose of this study was to assess the accuracy of distance and volume measurements obtained by three-dimensional ultrasonography. A tissue-mimicking phantom was scanned using a prototype three-dimensional sonographic imaging system to verify distance measurements. Measurements were taken from the reconstructed three-dimensional sonographic data and compared to the real distances. Volume measurements were obtained by scanning 30 balloons of various shapes, sized 23 ml to 2400 ml. Each balloon was scanned twice in two orientations; three different masks were accomplished for each volume. Each volume measurement of 180 three-dimensional sonographic measurements was compared to conventional two-dimensional ultrasonographic volume estimates and to the actual, measured balloon size. Distance measurements had a mean error of 0.02 +/- 3.65% (range, -4.27 to 7.18%). Two-dimensional sonographic volume estimates using traditional scanner based methods had a mean error of 13.7 +/- 10.1%. Three-dimensional sonographic volume measurements had a mean error of 2.2 +/- 2.9% for regular and irregular objects over the entire range of volumes. The masking required 10 to 30 min. The field of view varied from 10 to 24 cm with a mean object depth of 9.8 cm. Three-dimensional ultrasonographic methods can provide accurate volume measurements of regular and irregular objects and offer improved accuracy compared to traditional two-dimensional methods.

Equipment Design↗
PubMed1995

Fetal face visualization using three-dimensional ultrasonography.

Evaluation of the fetal face is an essential part of the sonographic examination for high risk pregnancies. Even under optimal conditions, the complex curvature of the face makes it difficult to obtain adequate images with two-dimensional ultrasonography, and many cross-sectional images are required to obtain a complete impression. The purpose of this paper is to show preliminary work in assessing the utility of three-dimensional ultrasonographic visualization of the fetal face. Fetal facial features were evaluated with three-dimensional sonography by scanning with a volume transducer and compared to conventional two-dimensional ultrasonographic images in 27 fetuses (gestational ages 10 to 39 weeks). Surface rendered three-dimensional sonographic images of the fetal face were obtained in 24 of 27 fetuses. In four cases the upper lip was clearly imaged on three-dimensional ultrasonography when it could not be seen on two dimensional ultrasonography. Information requiring multiple planes with two-dimensional ultrasonography could be demonstrated on a single image from three-dimensional ultrasonography. Images of abnormal faces were seen with both two- and three-dimensional ultrasonography in two cases of cleft lip and one case of holoprosencephaly. Volume data acquisition required approximately 10 sec and reconstruction required approximately 5 sec with instantaneous review of planes through the volume data set. Surface rendering required 2 to 10 min depending on the angular viewing range. Three-dimensional ultrasonography has the potential to provide improved visualization of the fetal face compared with conventional two-dimensional sonographic imaging.

Anencephaly↗
PubMed1994

Ultrasonography.

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Abdomen↗
PubMed1994

Prenatal visualization of cranial sutures and fontanelles with three-dimensional ultrasonography.

The anatomy of the cranial sutures and fontanelles in the developing fetus is difficult to evaluate using conventional two-dimensional ultrasonography (2DUS). Three-dimensional sonographic imaging (3DUS) was performed on eight normal volunteer pregnant patients after informed consent with conventional 2DUS equipment that had been adapted to obtain 3DUS images. 3DUS images of the cranium were evaluated for the presence of specific cranial sutures and fontanelles. Cranial sutures and fontanelles were identified with 3DUS in all fetuses scanned. The sutures most commonly identified included coronal, lambdoidal, and squamosal. The fontanelles most often identified included anterior, posterior, mastoid, and sphenoid. 3DUS offers the capability of identifying cranial sutures and fontanelles more clearly because volume rendered images show the cranial surface in its entirely rather than as a cross-sectional slice, offering the potential to identify pathologic cranial lesions currently not seen with 2DUS.

Cranial Sutures↗
PubMed1994

Significance of orbital measurements in the fetus.

Orbital imaging is not performed routinely during obstetrical sonography, but the discovery of abnormal orbital diameters provides evidence of fetal dysgenesis. This study was designed to establish the validity of a previously developed orbital nomogram for a high-risk population and to determine whether proved cases of hypotelorism and hypertelorism fell outside the normal ranges. Inner and outer orbital measurements of 422 fetuses were obtained prospectively during routine obstetrical sonography in a high-risk patient population. Comparison of these measurements to the previously established nomogram demonstrated that the nomogram is still accurate with current equipment and in a population at high risk for anomalies. In addition, sonograms and autopsy and clinical data from six cases of hypotelorism, two of cyclopia, and three of hypertelorism were reviewed retrospectively. Both inner and outer orbital measurements fell clearly below two standard deviations of the mean in all six cases of hypotelorism. The three cases of hypertelorism had inner orbital measurements above the 95th percentile and outer orbital distances within normal limits but near the 95th percentile. All cases with abnormal orbital distances had associated intra- or extracranial abnormalities, including holoprosencephaly, encephalocele, cleft palate, cardiac anomalies, imperforate anus, diaphragmatic hernia, and digit anomalies.

Anthropometry↗