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T R Nelson

Publications and source records attributed to T R Nelson.

At least 37 records · Page 2Linked to original sources
PubMed2000

Fetal lip and primary palate: three-dimensional versus two-dimensional US.

PURPOSE: To determine if three-dimensional (3D) ultrasonography (US) improves the ability to define the location and extent of facial clefting prenatally compared with two-dimensional (2D) US. MATERIALS AND METHODS: Thirty-one fetuses suspected of having a facial cleft were examined prospectively with 2D and 3D US. Follow-up was performed in all fetuses. RESULTS: Twenty-eight fetuses had a cleft lip at birth. The location of the cleft lip was correctly identified in all fetuses with 3D US and in 26 of 28 with 2D US. Twenty-two fetuses had a cleft primary palate. Nineteen and nine of 22 cleft palates were identified by using 3D and 2D US, respectively. Three fetuses suspected of having a facial cleft at 2D US had a normal palate at 3D US and at birth. CONCLUSION: Three-dimensional US is useful to identify the location and extent of facial clefting. The advantages of 3D US are the following: (a) The face may be viewed in a standard orientation, (b) the defect may be viewed systematically by using an interactive display, and (c) the rendered image provides landmarks for the planar images. Patient decisions may be affected, since they can view the abnormality on a recognizable 3D rendered image.

Cleft Lip↗
PubMed2000

Three-dimensional ultrasonographic imaging of the neonatal brain in high-risk neonates: preliminary study.

The aim of this investigation was to compare the utility of three-dimensional ultrasonography versus two-dimensional ultrasonography in imaging the neonatal brain. Thirty patients in the neonatal intensive care unit underwent two-dimensional and three-dimensional ultrasonography. The resultant two- and three-dimensional images recorded on film and three-dimensional volumes (reviewed on a workstation) were evaluated independently. Comparable numbers of normal and abnormal studies were diagnosed by each modality. Axial images were considered useful in approximately 50% of three-dimensional cases. Image quality, overall and in the far-field, was rated higher on two-dimensional images. Three-dimensional sonographic acquisition time in the neonatal intensive care unit (1.7 min+/-0.7 standard deviation) was significantly shorter than that for two-dimensional sonography (9.0+/-4.5 min). The total time for evaluation on the three-dimensional workstation (4.4+/-1.1 min) was significantly less than that for two-dimensional images on film (10.6+/-4.7 min). In conclusion, three-dimensional ultrasonography is a promising, diagnostically accurate, and efficient imaging tool for evaluation of the neonatal brain; however, visualization must improve before it can replace two-dimensional ultrasonography.

Brain↗
PubMed1999

Immunogenicity of P/Q-type calcium channel in small cell lung cancer: investigation of alpha1 subunit polyglutamine expansion.

The ectopic expression of neuronal P/Q-type voltage-gated calcium channels in small cell lung carcinoma (SCLC) is thought to induce antisynaptic autoimmunity in the paraneoplastic Lambert-Eaton myasthenic syndrome. The gene CACNL1A4, encoding the principal (alpha1A) subunit of this calcium channel, is mutated in several inherited neurological disorders. One of these disorders (spinocerebellar ataxia, type 6, or SCA-6) involves the expansion of a trinucleotide (CAG) repeat unit. We hypothesized that a somatic CAG repeat instability of this gene in neoplastic cells might generate a non-self epitope capable of initiating autoimmunity to P/Q-type calcium channels. We therefore analyzed the CACNL1A4 gene in SCLC lines established from metastases derived from seven individual patients (four associated with Lambert-Eaton myasthenic syndrome, one associated with myasthenia gravis, and two not associated with neurological autoimmunity). We compared their CAG repeat numbers (determined by polymerase chain reaction (PCR) amplification followed by separation of products on a 6% polyacrylamide/8M urea gel) to published norms and to DNA from a patient with SCA-6. The number of CAG repeats in SCLC DNA fell within a normal range whether or not the neoplasm was complicated by neurological autoimmunity. Therefore, it is unlikely that somatically unstable CAG repeat units in the gene encoding the P/Q-type voltage-gated calcium channel account for this tumor protein's immunogenicity in the Lambert-Eaton myasthenic syndrome.

Autoimmunity↗
PubMed1999

Normal splenic volumes estimated using three-dimensional ultrasonography.

The purposes of this study were to determine splenic volumes using three-dimensional ultrasonography and to compare these measurements with two-dimensional splenic indices. Fifty-two healthy volunteers were studied. Two-dimensional volume measurements were based on length, width, and thickness, and the splenic index was calculated using the standard prolated ellipsoid formula (length x width x thickness x 0.523). Three-dimensional volume planar measurements were obtained with a slice by slice technique by manually drawing a region of interest around the spleen from one end of the sweep to the opposite end. These measurements were recorded three times by two observers. In addition, in vitro determination of splenic volume was performed using three cadaveric human spleens in a water bath. No statistically significant interobserver or intraobserver variability was present for either two-dimensional or three dimensional ultrasonography. Three-dimensional sonographic estimations of planar splenic volumes and ellipsoid splenic volumes were consistently smaller than two-dimensional sonographic estimations of splenic volumes. Three-dimensional sonographic splenic volumes calculated in vitro using the planar method were accurate to within 2% of in vitro water displacement volumes. Three-dimensional ultrasonography is potentially superior to two-dimensional sonography for evaluation of irregularly shaped objects, such as the spleen, and can provide improved accuracy over that of traditional two-dimensional techniques.

Adult↗
PubMed1998

Three-dimensional fetal echocardiography.

The complex anatomy and dynamics of the heart make it a challenging organ to image. The fetal heart is particularly difficult because it is located deep within the mother's abdomen and direct access to electrocardiographic information is difficult. Thus more complex imaging and analysis methods are necessary to obtain information regarding fetal cardiac anatomy and function. This information can be used for medical diagnosis, model development and theoretical validation. The objective of this article is to provide scientists and engineers with an overview of three-dimensional fetal echocardiography.

Coronary Vessels↗
PubMed1998

Three-dimensional ultrasound imaging.

The objective of this article is to provide scientists, engineers and clinicians with an up-to-date overview on the current state of development in the area of three-dimensional ultrasound (3-DUS) and to serve as a reference for individuals who wish to learn more about 3-DUS imaging. The sections will review the state of the art with respect to 3-DUS imaging, methods of data acquisition, analysis and display approaches. Clinical sections summarize patient research study results to date with discussion of applications by organ system. The basic algorithms and approaches to visualization of 3-D and 4-D ultrasound data are reviewed, including issues related to interactivity and user interfaces. The implications of recent developments for future ultrasound imaging/visualization systems are considered. Ultimately, an improved understanding of ultrasound data offered by 3-DUS may 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 networks to review volume ultrasound data at specialization centers. Access to volume data and expertise at specialization centers affords more sophisticated analysis and review, further augmenting patient diagnosis and treatment.

Algorithms↗
PubMed1998

Shoring up the industry's valuations.

A simple option-pricing strategy to identify investment opportunities may enable companies to increase valuations and bolster shareholder value.

Biotechnology↗
PubMed1998

Imaging of placental vasculature using three-dimensional ultrasound and color power Doppler: a preliminary study.

OBJECTIVE: To assess placental vasculature using color power Doppler and three-dimensional ultrasound techniques. DESIGN: A prospective study was performed in patients to correlate visualization of placental vessels in vivo with known anatomy. SUBJECTS: Fourteen normal patients and one patient with intrauterine growth restriction were recruited to the study. METHODS: Vessels were assessed with regard to, first, the number of vessels seen within the placenta, second, the branching pattern of the vessels within the placenta, third, the number of vessels seen along the surface of the placenta, and, last, the number of vessels seen in the maternal circulation. RESULTS: Our results show that the placental vessels seen with this technique correlate well with known anatomy. A progressive increase in the number of intraplacental vessels and the number of vascular branches observed was seen with increasing gestational age. Volume data review using three orthogonal planar images had two distinct advantages. First, they could be obtained from orientations not possible using two-dimensional ultrasound alone, and, second, they could be viewed in conjunction with volume-rendered images to allow for referencing and identification of specific vessels. Volume-rendered images were valuable in allowing the observer to acquire an improved overall understanding of placental anatomy. They also assisted the observer in following the continuity of vessels as they wrapped around and twisted through three-dimensional space. Stereo viewing was helpful in distinguishing overlapping vessels. CONCLUSIONS: Our study showed that sonographic volume imaging combined with color power Doppler imaging methods allowed for individual vessels in the placenta to be identified, both in the fetal and maternal circulations.

Arteries↗
PubMed1998

Three-dimensional ultrasound examination of the fetal hands: normal and abnormal.

PURPOSE: To assess particular features of fetal hand evaluation using three-dimensional ultrasound, and to determine whether any advantage is offered by three-dimensional over two-dimensional ultrasound in fetal hand evaluation. METHODS: Three-dimensional fetal data were collected prospectively from 44 hands in 40 fetuses from a predominantly high-risk patient population. All had a concurrent two-dimensional ultrasound examination of the hands. Diagnoses from two- and three-dimensional ultrasound examinations were compared and additional information from the three-dimensional volume assessment was noted. Three-dimensional assessment of distal forearm bones, wrist position, finger configuration and number of metacarpals and digits was recorded. RESULTS: Hands were appropriately identified as normal (32/32) or abnormal (12/12) by both two- and three-dimensional ultrasound. Three-dimensional ultrasound provided additional information when compared to two-dimensional ultrasound in both normal and abnormal hands, including the provision of three orthogonal planes with one volume acquisition, allowing rotation of the volume so that hands could be evaluated in planes not possible during two-dimensional imaging, assessment of a hand with loosely curled fingers as normal, the ability to evaluate thumb and fingers simultaneously, and improved assessment of abnormal hands. CONCLUSIONS: Three-dimensional ultrasound offers the potential to provide greater information in fetal hand evaluation for both normal and abnormal hands.

Embryonic and Fetal Development↗
PubMed1998

Tubulointerstitial nephritis antigen (TIN-ag) is expressed in distinct segments of the developing human nephron.

Tubulointerstitial nephritis antigen (TIN-ag) is a 58 kDa glycoprotein restricted within the kidney to basement membranes underlying the epithelium of Bowman's capsule and proximal and distal tubules. Autoantibody formation against this component has been described in association with primary immune-mediated tubulointerstital nephritis, membranous nephropathy and anti-glomerular basement membrane nephritis. In the present report, the ontogeny of this protein was studied in human fetal kidney tissue by immunohistochemical analysis of immature and developing nephrons using a panel of monoclonal and polyclonal antibodies. TIN-ag is first detected in basement membranes underlying the epithelium of Bowman's capsule of early capillary loop stage glomeruli and the primitive proximal tubule. No detectable expression is observed in the basement membranes of the branching ureteric bud, nephrogenic vesicle, or comma shape and s-shape stages of nephrogenic development. Increased staining of the proximal tubular basement membrane is associated with outgrowth of the primitive tubule from the urinary pole of the developing glomerulus. In more mature fetal tubules, TIN-ag expression closely resembles that of previously reported observations in mature tissue where it is present in high amounts in the basement membranes of proximal tubules, and to a lesser extent in Bowman's capsule and distal tubules. Our results suggest that TIN-ag expression is developmentally regulated in a precise spatial and temporal pattern throughout nephrogenesis.

Antibodies, Monoclonal↗
PubMed1998

Three-dimensional ultrasonography of the fetal distal lower extremity: normal and abnormal.

The objective of this study was to compare two-dimensional and three-dimensional ultrasonographic evaluation of fetal distal lower extremities. Data from two-dimensional and three-dimensional ultrasonographic examinations from 40 distal lower extremities in 33 fetuses from a predominantly high-risk patient population were compared. Three-dimensional ultrasonography routinely provided three orthogonal planes (coronal, sagittal, and axial) for distal lower extremity evaluation. Specific features of distal lower extremity evaluation were not different using two-dimensional and three-dimensional ultrasonography. Rotation of the rendered volume provided assistance in assessing all but one of 40 distal lower extremities. Time from image acquisition to assessment for two views (coronal and sagittal) was longer with three-dimensional ultrasonography (8.2 min) than with two-dimensional ultrasonography (3.2 min). Confidence in the diagnosis of abnormal distal lower extremities was slightly improved using three-dimensional ultrasonography compared to two-dimensional ultrasonography. Pregnancy management was assisted in three of the four cases with isolated limb anomalies. In conclusion, three-dimensional ultrasonography improves the ability to evaluate the fetal distal lower extremity because of the multiplanar nature of volume assessment and the ability to rotate volume data sets. In addition, it provides assistance in counseling families, particularly for cases involving isolated limb anomalies.

Female↗
PubMed1998

Three-dimensional gray scale ultrasonographic imaging of the celiac axis: preliminary report.

The vessels of the celiac axis were evaluated in 16 healthy volunteers with three-dimensional gray scale ultrasonography. Sonographic volume data sets were obtained from both sagittal and transverse planes. The visualization of specific branches of the celiac artery (hepatic, splenic, left gastric, gastroduodenal, left hepatic, right hepatic, right gastric) was evaluated, and each vessel was placed in one of four categories on the basis of the appearance of the specific vessel and image clarity (not seen, poorly seen, adequately seen, well seen). Each vessel was evaluated on an initial two-dimensional scan and on a second scan using the entire volume to optimize and follow the designated vessel using rotating, referencing, and scrolling display capabilities. The ability to manipulate an entire volume improved visualization of the selected vessels as noted by an improved score. The proportion of vessels in the "not seen" and "poorly seen" categories decreased from the initial scan (62.5%) to the scan utilizing the entire volume (36%). Alternatively, the percentage of vessels in the "adequately seen" to "well seen" categories improved from 37.50% on the initial examination to 64% on the scans using the entire volume to depict vascular anatomy. The optimal plane to image each vessel depended on the course of a specific vessel. For optimal imaging of all the selected vessels, both sagittal and transverse volume acquisitions and both sagittal and transverse planes were needed. Three-dimensional imaging provided a new imaging plane (coronal) that was useful in following and identifying vessels, especially those vessels coursing in a right to left direction. Vascular variants were identified by this technique in two of 16 subjects. Vascular imaging was improved with three-dimensional ultrasonography, and this imaging method may provide additional assistance in decision making when evaluating abdominal vessels.

Adult↗
PubMed1998

Three-dimensional ultrasonography of normal fetal heart: comparison with two-dimensional imaging.

Thirty-one high-risk patients (16 to 35 weeks' gestation) underwent two-dimensional and three-dimensional ultrasonography to compare two-dimensional and non-cardiac-gated three-dimensional ultrasonography of the normal fetal heart. After normal two-dimensional studies, three-dimensional sonographic volumes were acquired without cardiac gating in transverse and longitudinal planes. Standard cardiac views were derived from three-dimensional data, analyzed, and rated as follows: (1) not identifiable, (2) identifiable but inadequate for diagnosis, (3) adequate, and (4) excellent. Two-dimensional ultrasonography demonstrated better yields of diagnostically acceptable images of basic echocardiographic views (four-chamber view, 100% for two-dimensional sonography versus 10 to 71% for three-dimensional sonography; right ventricular outflow tract, 42% for two-dimensional versus 6 to 26% for three-dimensional ultrasonography; left ventricular outflow tract, 71% for two-dimensional versus 13 to 45% for three-dimensional sonography). In one subject three-dimensional ultrasonography was superior to two-dimensional sonography in demonstrating an outflow tract. Aortic and ductal arches were not imaged with the two-dimensional technique but were available from the acquired three-dimensional volumes in 3 to 32% and 23%, respectively. False-positive and false-negative findings were observed on three-dimensional ultrasonograms. Overall, compared to two-dimensional ultrasonography, non-cardiac-gated three-dimensional sonography yielded inadequate reconstructed image quality of basic echocardiographic views (four-chamber view, right ventricular outflow tract, left ventricular outflow tract). Three-dimensional ultrasonography, however, shows potential for allowing nonechocardiographers to acquire some diagnostically acceptable views of the aortic and ductal arches.

Echocardiography, Three-Dimensional↗
PubMed1998

Three-dimensional fetal echocardiography: gated versus nongated techniques.

The purpose of this study was to compare gated with nongated three-dimensional fetal echocardiography in terms of the ability to demonstrate fetal cardiac anatomy. We examined nine fetuses in utero using conventional two-dimensional sonographic imaging equipment, an electromagnetic position sensor, and a computer-graphics workstation. Free-hand sweeps were performed through the fetal heart and great vessels in either transverse or sagittal orientations with respect to the fetal heart. Seven transverse and five sagittal sweeps were selected for reconstruction and analysis. Cardiac gating was performed by using a temporal Fourier transform to determine the fundamental frequency of cardiac motion. Two-dimensional data from each sweep were reprojected to a series of volume data sets. Each series was then condensed to a single volume, so that each two-dimensional sweep could be compared with its respective gated and nongated volume data sets. The two-dimensional data were reviewed utilizing a display with forward and backward cineloop capability. The gated and nongated volume data sets were displayed interactively as a series of three orthogonal planes, with the ability of the observer to control the location of each image plane within the volume. The gated data were animated with variable display frame rates. Conventional two-dimensional imaging provided a fairly complete evaluation of the fetal heart when scanning included the four-chamber view with a sweep across the outflow tracts. Nongated three-dimensional fetal echocardiography allowed visualization of some structures and views not demonstrated with two-dimensional ultrasonography. Gated three-dimensional fetal echocardiography provided significantly better visualization and comprehension of cardiac anatomy than nongated three-dimensional fetal echocardiography. The superiority of gated over nongated three-dimensional fetal echocardiography appears to come from both improved image quality and the anatomic clues that derive from the ability to view cardiac motion.

Echocardiography, Three-Dimensional↗