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Biomedical subjects

A Kratochwil

Publications and source records attributed to A Kratochwil.

At least 19 recordsLinked to original sources
PubMed2000

Networking of three dimensional sonography volume data.

Three-dimensioned (3D) sonography enables the examiner to store, instead of copies from single B-scan planes, a volume consisting of 300 scan planes. The volume is displayed on a monitor in form of three orthogonal planes--longitudinal, axial and coronal. Translation and rotation facilitates anatomical orientation and provides any arbitrary plane within the volume to generate organ optimized scan planes. Different algorithms allow the extraction of different information such as surface, or bone structures by maximum mode, or fluid filled structures, such as vessels by the minimum mode. The volume may contain as well color information of vessels. The digitized information is stored on a magnetic optical disc. This allows virtual scanning in absence of the patient under the same conditions as the volume was primarily stored. The volume size is dependent on different, examiner-controlled settings. A volume may need a storage capacity between 2 and 16 MB of 8-bit gray level information. As such huge data sets are unsuitable for network transfer, data compression is of paramount interest. 100 stored volumes were submitted to JPEG, MPEG, and biorthogonal wavelet compression. The original and compressed volumes were randomly shown on two monitors. In case of noticeable image degradation, information on the location of the original and compressed volume and the ratio of compression was read. Numerical values for proving compression fidelity as pixel error calculation and computation of square root error have been unsuitable for evaluating image degradation. The best results in recognizing image degradation were achieved by image experts. The experts disagreed on the ratio where image degradation became visible in only 4% of the volumes. Wavelet compression ratios of 20:1 or 30:1 could be performed without discernible information reduction. The effect of volume compression is reflected both in the reduction of transfer time and in storage capacity. Transmission time for a volume of 6 MB using a normal telephone with a data flow of 56 kB/s was reduced from 14 min to 28 s at a compression rate of 30:1. Compression reduced storage requirements from 6 MB uncompressed to 200 kB at a compression rate of 30:1. This successful compression opens new possibilities of intra- and extra-hospital and global information for 3D sonography. The key to this communication is not only volume compression, but also the fact that the 3D examination can be simulated on any PC by the developed 3D software. PACS teleradiology using digitized radiographs transmitted over standard telephone lines. Systems in combination with the management systems of HIS and RIS are available for archiving, retrieval of images and reports and for local and global communication. This form of tele-medicine will have an impact on cost reduction in hospitals, reduction of transport costs. On this fundament worldwide education and multi-center studies becomes possible.

Algorithms↗
PubMed1999

Three-dimensional ultrasonographic imaging of fetal tooth buds for characterization of facial clefts.

The purpose of this prospective study was to investigate whether the antenatal characterization of fetal facial clefts can be improved by three-dimensional ultrasonographic visualization of fetal tooth buds. Between January 1996 and June 1998, seventeen consecutive fetuses with facial clefts were examined for fetal maxillary tooth buds in the cleft area using three-dimensional multiplanar reconstruction. It was possible in all cases to classify the clefts either as cleft lip alone or unilateral cleft lip and palate or bilateral cleft lip and palate. Three-dimensional computed tomography and histological jaw sections of three stillborn infants were produced in order to examine the correlation between the sonographic, radiographical and histological findings. The prenatal characterization of the facial clefts by means of a visualization of the tooth buds showed to be accurate postnatally in all cases. The sonographic proof of tooth buds might gain increasing importance as this technique seems to facilitate and improve the prenatal classification of suspected facial clefts.

Adult↗
PubMed1999

Ultrasound evaluation of fetal spine length between 14 and 24 weeks of gestation.

The objective of our study was to establish a nomogram of fetal spine length in the second trimester of pregnancy by using two and three-dimensional ultrasound. Fetal spine length was measured prospectively by means of transabdominal ultrasonography in 114 normal singleton pregnancies between 14 and 24 weeks of gestation. Regression analyses were performed on spine length, gestational age, biparietal diameter and femur length. Supplementary three-dimensional ultrasound to assess fetal spine length was performed in 75 cases. Fetal spine length, as a function of gestational age, was expressed by the following regression equation: spine length (mm) = -47.2 + 7.16 x gestational age (weeks), with a Pearson correlation coefficient of R(2)=0.956. The results of the measurements revealed no difference between two and three-dimensional ultrasound. Our study defines the normal limits of fetal spinal length in the second trimester of pregnancy and demonstrates a high correlation between spinal length, gestational age, biparietal diameter and femur length. However, there are still too few prenatal research data to say whether and to what extent an assessment of fetal spine length at this stage of pregnancy can be used for prenatal diagnosis of congenital syndromes, which, among other manifestations, are marked by fetal spine lengthening or shortening.

Female↗
PubMed1998

Three-dimensional ultrasound evaluation of fetal tooth germs.

OBJECTIVE: A total of 126 genetic syndromes are associated with oligodontia or anodontia. The most frequent of these are ectodermal dysplasias, all types of facial cleft and Down's syndrome. With the advent of three-dimensional ultrasonography, accurate assessment of many fetal abnormalities has become possible. The objective of this study was to determine the effectiveness of three-dimensional ultrasonography in the visualization of fetal tooth germs. DESIGN: We examined 45 women with singleton pregnancies between 16 and 36 gestational weeks who were undergoing routine ultrasound check-ups for fetal tooth germs with conventional two-dimensional ultrasonography, followed by three-dimensional ultrasonography using multiplanar reconstruction. RESULTS: In the 45 fetuses studied, fetal tooth germs were visualized at the first attempt in 36 cases (80%). In the group of fetuses aged between 19 and 36 weeks of gestation, the overall detection rate in both jaws was at least 86% for three-dimensional ultrasonography, compared to at least 56% for two-dimensional ultrasonography. CONCLUSIONS: Three-dimensional ultrasonography was clearly superior to conventional ultrasonography in the visualization and evaluation of fetal tooth germs. Three-dimensional ultrasonography therefore has a potential for enhanced visualization of fetal tooth germs and may aid in the antenatal detection of syndromes associated with oligodontia or anodontia.

Cleft Lip↗
PubMed1997

Endometrial volume change during spontaneous menstrual cycles: volumetry by transvaginal three-dimensional ultrasound.

OBJECTIVE: At present, only limited data are available on endometrial volume during the menstrual cycle. Most of these studies deal with animal models and use magnetic resonance imaging for volume measuring. The application of three-dimensional ultrasound in endometrial volume estimation is the subject of this study. SETTING: Patients visiting the outpatient unit of the division of endocrinology and reproductive medicine of a university hospital. PATIENT(S): Twenty patients with a history of a normal menstrual cycle were selected. INTERVENTION(S): Ultrasound examinations were performed during a single menstrual cycle in addition to routine laboratory tests. MAIN OUTCOME MEASURE(S): Uterus-endometrial volume ratio. RESULT(S): Data from 18 patients could be evaluated. In 81 examinations the endometrium volume could be determined. Mean endometrial volume measured by three-dimensional ultrasound was 1.23 cm3. Mean uterus volume was 48.93 cm3. The change of the uterus-endometrial volume ratio showed a good correlation with the day of menstrual cycle. Quadratic regression analysis of volume and cycle length was R2 = 0.432. CONCLUSION(S): Three-dimensional ultrasound allows assessment of volume data of the female internal genitalia. In this study changes of the endometrial volume in menstrual cycles were measured. Additional studies are required to give information on the clinical impact of this new technique of endometrial volume estimation.

Endometrium↗
PubMed1997

Intrauterine device localization by three-dimensional transvaginal sonography.

Our objective was to investigate the possible role of three-dimensional transvaginal ultrasound in the visualization of an intrauterine device (IUD) for routine follow-up after insertion. A total of 96 women were examined after insertion of a TCu380A IUD. Three-dimensional ultrasonographic imaging was carried out using a special vaginal probe and a commercially available ultrasound machine at a mean interval of 22 days after insertion. Complete simultaneous imaging of all parts of the IUD was possible in 95% of cases. In the three-plane mode, all parts of the IUD could be visualized in 64% and in a further 30 cases this was possible only after volume rendering. In two women, incomplete opening of the two arms of the device was demonstrated. In one of these cases, the entire IUD was displaced into the cervical canal. In another case, an intrauterine pregnancy was found together with an IUD in the correct position. Three-dimensional ultrasound provides useful information on the location of the IUD following insertion. It enables imaging of the entire IUD, i.e. the shaft and the arms, simultaneously. Additionally, the examination time can be kept to a minimum with this new technique.

Adult↗
PubMed1996

Three-dimensional saline contrast hysterosonography and surface rendering of uterine cavity pathology.

A new technique that combines saline contrast hysterosonography with three-dimensional surface rendering for the visualization of uterine intracavitary pathologies is described. A total of 32 patients suspected of having uterine cavity pathologies on the basis of previous ultrasonography, hysterosalpingography or hysteroscopy were involved in the study. They were examined by three-dimensional high-frequency endovaginal probes (Combison 530, Kretztechnik, Zipf, Austria), with normal saline used as an expander and contrast medium. Three perpendicular planes could be evaluated simultaneous, and surface renderings were readily available. Following the instillation of normal saline, the uterine cavity appears as an echo-free, well-defined structure, and the endometrium appears as an echogenic homogeneous lining around the cavity. Data acquisition time is short and images can be stored for later evaluation. Surface rendering of polypoid structures shows echogenic masses on a pedicle protruding into the uterine cavity. Submucous fibroids appear as mixed echogenic sites bulging into the cavity. Intrauterine synechiae appear as bands of varying thickness traversing the uterine cavity. Simultaneous display of the zone of interest in three perpendicular planes enhances imaging capabilities, while surface rendering provides a comprehensive overview of the surface area of the findings and their topographical orientation. Further research using this new technique is required to document its real contribution to ultrasonographic imaging.

Contrast Media↗
PubMed1996

Fetal lung volume determination by three-dimensional ultrasonography.

OBJECTIVE: Pulmonary hypoplasia is common in compromised pregnancies. However, prenatal diagnosis by volume measurement has not become routine until now. The performance of three-dimensional ultrasonography in fetal lung volume determination was evaluated in this study. STUDY DESIGN: In a total of 78 singleton pregnancies 108 measurements were performed. Lung volume was calculated by subtraction of the fetal heart volume from the volume of the fetal thorax. RESULTS: Linear regression of transformed fetal lung volume growth gave best results (R2 = 0.77, p < 0.001), ranging from 2.8 ml at 14 weeks' gestation to 148 ml at term. CONCLUSION: Three-dimensional ultrasonography provides not only access to surface rendered images but it also enables more sophisticated volume measurements. In this study three-dimensional ultrasonography provided fast, easy access for volume estimation of the fetal lung. This technique can be used to reasonably predict fetal lung volume.

Female↗
PubMed1996

Antenatal depiction of fetal digits with three-dimensional ultrasonography.

OBJECTIVE: The effectiveness of three-dimensional ultrasonography in visualizing fetal digits was examined. STUDY DESIGN: The digits of 72 fetuses, including 2 with skeletal dysplasia, were examined prospectively with both conventional and three-dimensional ultrasonography. RESULTS: Complete visualization of all fetal digits was obtained more often with three-dimensional ultrasonography than with two-dimensional ultrasonography. CONCLUSION: Three-dimensional ultrasonography has the potential to facilitate depiction of fetal digits, which may enhance prenatal identification of fetal malformations and chromosomal abnormalities in high-risk pregnancies.

Female↗
PubMed1995

Three-dimensional ultrasound in diagnosing phocomelia.

Deformations of the extremities with limb reduction are rare congenital defects which affect one in 1692 live babies. Three-dimensional ultrasound can be of value in the prenatal diagnosis of such deformities. We present a case of upper phocomelia and congenital thrombocytopenia (TAR syndrome). Visualization of the upper extremities was achieved by three-dimensional ultrasound after surface and volume rendering. This new technique allows imaging not only of surfaces like the fetal skin, but also of internal structures like the fetal skeleton.

Adult↗
PubMed1992

[Attempt at three-dimensional imaging in obstetrics].

Different attempts have been already made to present sonographic findings in 3 dimensions. In most of computer assisted systems the time for acquiring and data processing is too long to allow for an instantaneous interaction between the examiner and the machine; furthermore, valuable data; concerning the organ structure were lost. The aim of the system presented here is to acquire short time a sample volume for 3 dimensional display without employing an expensive periphery, containing all relevant sonic data and without substantial changes in handling the equipment. The technical details, advantages and shortcomings of the equipment are discussed. First results in obstetrics and gynaecology are presented.

Brain↗
PubMed1987

[Use of sonography at the peripheral hospital in the diagnosis of kidney tumors].

33 kidney tumours were detected in 15,500 routine scans of the upper abdomen. 13.7 per cent of these tumours were asymptomatic at the time of diagnosis. The size of these accidentally detected tumours was evidently smaller than in the case of symptomatic ones and the patients were younger at the time of diagnosis. The diagnosis was falsely positive in one case and falsely negative in 3 cases. In 2 cases of incorrect negative findings the sonographic diagnosis was hydronephrosis, but IVP and cytology of the specimen proved that these tumours were urothelial carcinomas. Apparently the weak point in sonographic diagnosis is the diagnosis of urothelial carcinomas. In cases of suspected kidney tumour or a sonographic diagnosis of hydronephrosis additional diagnostic methods must be undertaken. Our results show that adequate and cost-effective diagnostic information in the detection of kidney tumours is obtained in the majority of cases by sonography and urography.

Adenocarcinoma↗
PubMed1986

Prenatal diagnosis of fetal malformations by ultrasonography.

Ultrasonography is today able to detect many details of the fetal anatomy, so that prenatal diagnosis of malformations becomes possible. However, as 60% of all detected fetal abnormalities develop spontaneously, a screening program is recommended. At least two ultrasonic examinations should be performed. To cope with the huge number of examinations obstetricians in their offices are integrated in this program. Women carrying fetuses with identified or suspected anomalies are sent for further evaluation, management, and counseling to special clinics. The task is to differentiate between lesions which are incompatible with postnatal life, lesions which will necessitate a supporting person for the life of the patient, and lesions which are correctable by surgery. To gain more experience, close cooperation with neonatologists, pediatric surgeons, neurologists, and geneticists is recommended. The first advantages of early prenatal diagnosis have been elective cesarean and reduction of postnatal evaluation and treatment required.

Bone and Bones↗
PubMed1985

[Quality control in obstetrical ultrasound diagnosis].

Experience with sonographic pregnancy care have demonstrated the necessity of quality control. Before a person is licensed to take account for sonography he should prove, that he has performed a certain number of examinations and that he is holding a file of documents on these examinations. This certificate should ensure that the fundamental knowledge of foetal sonographic anatomy and biometry as well as of possible signs of foetal malformations have been correctly acquired. As a provisional arrangement until sonography is fully integrated into gynaecological education, an examination by a board would appear to be desirable.

Cephalometry↗