Direct volume rendering algorithms are too computationally expensive to offer interactive frame r... more Direct volume rendering algorithms are too computationally expensive to offer interactive frame rates when rendering large 3D medical datasets on standard workstations. This article presents an image space parallelization of an image order volume rendering algorithm aimed at shared memory multiprocessors. This parallel implementation of direct volume rendering can significantly speed up rendering times and visualize 3D datasets with speeds of several frames per second. The algorithm was implemented and evaluated on Convex SPP Exemplar and SGI Challenge multiprocessors.
The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visual... more The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visualized with a 3D virtual reality system. METHODS: We analysed 48 3D ultrasound scans of 19 IVF/ICSI pregnancies at 7-10 weeks' gestation. These datasets were visualized as 3D 'holograms' in the BARCO I-Space virtual reality system. Embryos were staged according to external morphological features (i.e. mainly limb development). After staging, the crown rump length (CRL) was measured. Stage and CRL were compared with gestational age based on the date of oocyte retrieval and with the classical data on embryology from the Carnegie Collection. RESULTS: Embryonic staging was relatively easy because the I-Space allows depth perception, which helps in the estimation of size and position. The presumed stages corresponded well with the measured CRL. However, in 28 out of 48 cases, the stages seemed to have been reached earlier than previously described for the Carnegie Collection. CONCLUSIONS: The I-Space, tentatively named Virtual Embryoscopy, is a promising non-invasive tool for early pregnancy evaluation. Combining embryonic growth with embryonic development opens a new area to study the relationship between embryonic growth, development and morphology, as well as second and third trimester pregnancy complications.
Ultrasound in Obstetrics & Gynecology, Sep 21, 2007
17th World Congress on Ultrasound in Obstetrics and Gynecology Oral poster abstracts signs. This ... more 17th World Congress on Ultrasound in Obstetrics and Gynecology Oral poster abstracts signs. This has proven to predict CA with a high degree of accuracy when compared to placental histology. We aimed to investigate whether scans in earlier pregnancy can be used to diagnose CA with similar reliability. Methods: This was a retrospective study of twin pregnancies over a three-year period. Women with viable twin pregnancies who underwent a transvaginal scan (TVS) between 7 and 9 weeks of gestation were included in the analysis, and CA documented. This was compared to the respective diagnoses of CA at the 11-14 week scan. CA at the 11-14 week scan was assumed to be diagnostic, given the previously reported high sensitivity and specificity. Results: 69 women with viable twin pregnancies between 7 and 9 weeks also attended for an 11-14 week scan at our hospital. In five women spontaneous single fetal demise occurred between scans and were excluded. Of the remaining twins, CA was documented in 58 cases at 7-9 weeks. Overall, there was agreement in CA between the two scans in 55 of these 58 (94.8%). Agreement was highest for dichorionic-diamniotic (DCDA) pregnancies at 7-9 weeks: 44/45 (97.8%) were confirmed as DCDA and 1 (2.2%) as monochorionic-diamniotic (MCDA) at the 11-14 week scan. Of the 11 MCDA pregnancies at 7-9 weeks, 10 (90.9%) were found to be MCDA and one (9.1%) DCDA. There were two monochorionic-monoamniotic (MCMA) pregnancies diagnosed at 7-9 weeks, of which one was subsequently found to be MCMA while the other was MCDA. Conclusions: TVS at 7-9 weeks will correctly diagnose CA in about 95% of twin pregnancies. Accuracy may be higher for DCDA twins than MCDA twins and this may relate to the gestation at which sonographic appearance of the amniotic sac occurs.
Ultrasound in Obstetrics & Gynecology, Sep 1, 2012
The automated method showed accurate prediction of the manually labelled planes with an average s... more The automated method showed accurate prediction of the manually labelled planes with an average sensitivity of 91.29% and a positive predictive value of 76.29%. Through closer inspection, all false positive planes selected by the automated method contained both the SB and UV in the correct position but had not been selected by the expert because of stricter criteria imposed. Conclusions: Our results show that machine learning can be used to automatically select a correct AC plane from a fetal 3D volume, and is an early first step in the direction of automated fetalsonography. Such an automated method has the potential for reducing the time needed to complete an ultrasound examination or to perform offline examinations. Further work will be needed to evaluate this and to extend it to other areas of fetal biometry.
In this chapter we take a look at the possible applications of volume visualization in immersive ... more In this chapter we take a look at the possible applications of volume visualization in immersive virtual environments, and how they can be implemented. Nowadays, the availability of many kinds of 3D imaging modalities, like CT, MRI and 3D ultrasound, gives clinicians an unprecedented ability to look inside a patient without the need to operate. However, while these datasets are three dimensional, they are still presented on 2D (flat) screens. While most systems and workstations offer a volume rendering option to present the data, when projected onto a normal screen (or printed on paper or film), the images are not truly 3D and are often termed “2.5D.” By using a virtual reality system that immerses the viewer(s) in a truly three-dimensional world, we hope to improve the understanding of these images.
Welcome to the 2001 IEEE Symposium on Parallel and Large Data Visualization and Graphics (PVG2001... more Welcome to the 2001 IEEE Symposium on Parallel and Large Data Visualization and Graphics (PVG2001). This year's proceedings are dominated by scientific applications of parallel visualization, a subject that will be explored in the panel discussion. Other noticeable trends this year are the increasing prevalence of PC graphics clusters and the use of out-of-core techniques as alternatives to traditional parallelism. The following are summary descriptions of the program presentations. KEYNOTE ADDRESS In keeping with this year's theme of "large data" our invited keynote address is by the research staff at Celera Genomics Corporation. This contribution (with 14 co-authors) describes their experiences developing and using visualization tools during the process of mapping the human genome, and forward-looking challenges in the emerging field of proteomics. We believe this discussion is timely and hope it will lead to future work in these areas. VECTOR FIELD VISUALIZATION This set of papers presents three approaches to visualizing vector fields produced by large simulations of three dimensional fluids. Cruz, Godoy, Garcia & Ramos devise a technique that captures the surface deformations of a flow field over time. The technique makes visible the stretching and folding that characterizes fluid mixing, and is demonstrated on a cluster of commodity PCs and on an SGI Origin. Crossno, Angel & Munich compare three fast methods for mapping 3D vectors into color space, and apply the methods to visualizing an ocean circulation model. The methods exploit human psychophysical properties to maximize the efficiency of the color encoding. Bruckschen, Kuester, Hamann & Joy explore real time out-of-core particle tracing for large time varying vector fields. Their system runs on a commodity PC running Linux equipped with a RAID. SURFACES AND PARALLEL RENDERING This eclectic session begins with a paper by Dey, Giesen & Hudson that presents a Delaunay based surface reconstruction algorithm for creating polygonal models from a very large number of sample points. They employ a divide-and-conquer strategy in order to minimize memory usage. With their new method it is now possible to reconstruct a surface from one million points on a modest PC. Reinhard, Shirley & Hansen describe a parallel point projection method that may be used to increase image size and scene complexity during interactive ray tracing. They have created a parallel Render Cache and have applied it to the concept of frameless rendering. The next two papers explore parallel rendering on PC clusters. Samanta, Funkhauser & Li have developed a K-way replication scheme that distributes each 3D primitive of a scene to only K number of PCs in a rendering cluster. They show that parallel rendering efficiencies produced with small replication factors are similar to ones using full replication. Moreland, Wylie & Pavlakos present a scalable, sort-last parallel rendering system running on a PC cluster that is capable of rendering extremely large geometric models onto high-resolution tile displays. They exploit the spatial coherency of their data in order to render 120 million triangles/second on a 12 megapixel display. SOFTWARE INFRASTRUCTURE FOR PARALLEL VISUALIZATION In this session two frameworks are presented for visualizing large datasets. The first paper by Law, Henderson & Ahrens is a case study describing the use of the well-known Visualization Toolkit (VTK) software for rendering large datasets, with an application to ocean current simulations. The second paper by Bartz, Staneker, Strasser, Cripe, Gaskins, Orton, Carter, Johannsen & Trom describes the Open Source "Jupiter" toolkit, and new occlusion culling extensions for interactively rendering very large polygonal models like those typically generated by CAD-packages. ARCHITECTURES FOR STRUCTURED VOLUME RENDERING This session presents two architectures for ray-casting structured volume datasets. MeiBner, Grimm, StraBer, Packer & Latimer present an implementation of a parallel ray-casting algorithm on a new single-chip SIMD architecture. Concurrent ray-processing is scheduled to produce efficient memory access and the ray-casting algorithm is mapped onto the architecture to avoid floating point calculations. Lombeyda, Mall, Shand, Breen & Heirich describe a PC cluster architecture utilizing SEPIA and Volume Protechnology that is capable of interactively rendering large data volumes. The architecture uses dynamically-mapped associative blending operators in a sort-last configuration to merge streams of images of subvolumes rendered on separate PCs into a single stream in real-time. PANEL - PARALLELISM: RENDERING, VISUALIZATION AND LARGE DATA The focus of this symposium has evolved over the years. The symposium began in 1993 as the Parallel Rendering Symposium (PRS) and primarily focused on parallel photorealistic rendering issues. In 1999 the symposium was expanded to include parallel volume visualization and changed its…
This paper presents the work that has been carried out at SARA on various projects that use volum... more This paper presents the work that has been carried out at SARA on various projects that use volume rendering techniques to explore 3D (i.e., volumetric) datasets in the CAVE virtual reality environment. The stereoscopic, large-format images of the CAVE offer insights into the data that a normal rendering viewed on a monitor does not. After evaluating the few existing volume rendering programs available for the CAVE, we concluded that we needed to develop our own software, if we wanted an up-to-date, robust, and extensible application. Because our CAVE is driven by a high-end Silicon Graphics computer, the use of a (hardware assisted) 3D texture-mapping algorithm is the most obvious choice. With this algorithm, interactive framerates can be obtained, which is essential for use in a VR environment. We have used the resulting software, dubbed CAVORE for CAve VOlume REndering, to explore both medical and biological datasets and are extending it with new options as required by the ongoing projects.
Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed AC... more Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed ACL reconstruction. Accurate and reproducible methods to visualize and document bone tunnel placement are therefore important. We evaluated the reliability of standard radiographs, CT scans, and a 3-dimensional (3D) virtual reality (VR) approach in visualizing and measuring ACL reconstruction bone tunnel placement. Methods 50 consecutive patients who underwent single-bundle ACL reconstructions were evaluated postoperatively by standard radiographs, CT scans, and 3D VR images. Tibial and femoral tunnel positions were measured by 2 observers using the traditional methods of Amis, Aglietti, Hoser, Stäubli, and the method of Benereau for the VR approach. Results The tunnel was visualized in 50-82% of the standard radiographs and in 100% of the CT scans and 3D VR images. Using the intraclass correlation coefficient (ICC), the inter-and intraobserver agreement was between 0.39 and 0.83 for the standard femoral and tibial radiographs. CT scans showed an ICC range of 0.49-0.76 for the inter-and intraobserver agreement. The agreement in 3D VR was almost perfect, with an ICC of 0.83 for the femur and 0.95 for the tibia. Interpretation CT scans and 3D VR images are more reliable in assessing postoperative bone tunnel placement following ACL reconstruction than standard radiographs.
Ultrasound in Obstetrics & Gynecology, Aug 1, 2016
. This study compared measurements of levator ani hiatal volume during rest and on maximum Valsal... more . This study compared measurements of levator ani hiatal volume during rest and on maximum Valsalva, obtained using conventional three-dimensional (3D) translabial ultrasound and virtual reality imaging. Our objectives were to establish their agreement and reliability, and their relationship with prolapse symptoms and POP quantification (POP-Q) stage. Methods One hundred women with an intact levator ani were selected from our tertiary clinic database. Information on clinical symptoms were obtained using standardized questionnaires. Ultrasound datasets were analyzed using a rendered volume with a slice thickness of 1.5 cm, at the level of minimal hiatal dimensions, during rest and on maximum Valsalva. The levator area (in cm 2 ) was measured and multiplied by 1.5 to obtain the levator ani hiatal volume (in cm 3 ) on conventional 3D ultrasound. Levator ani hiatal volume (in cm 3 ) was measured semi-automatically by virtual reality imaging using a segmentation algorithm. Twenty patients were chosen randomly to analyze intra-and interobserver agreement. The mean difference between levator hiatal volume measurements on 3D ultrasound and by virtual reality was 1.52 cm 3 (95% CI, 1.00-2.04 cm 3 ) at rest and 1.16 cm 3 (95% CI, 0.56-1.76 cm 3 ) during maximum Valsalva (P < 0.001). Both intra-and interobserver intraclass correlation coefficients were ≥ 0.96 for conventional
Journal of Obstetrics and Gynaecology Research, Jan 29, 2022
Introduction: To investigate the reproducibility of first-trimester fetal organ volume measuremen... more Introduction: To investigate the reproducibility of first-trimester fetal organ volume measurements using three-dimensional (3D) ultrasound and a Virtual Reality system. Methods: Within a population-based prospective cohort study, 3D ultrasound datasets of 25 first-trimester fetuses were collected by three sonographers. We used the V-scope application to perform Virtual Reality volume assessments of the fetal heart, lungs, and kidneys. All measurements were performed by two independent researchers. Results: Intraobserver analyses for volume measurements of the fetal heart, lungs, and kidneys showed intraclass correlation coefficients ≥0.86, mean differences ≤8.3%, and coefficients of variation ≤22.8%. Interobserver analyses showed sufficient agreement for right lung volume measurements, but consistent measurement differences between observers for left lung, heart, and kidney volume measurements (p-values <0.05). Conclusion: We observed sufficient intraobserver reproducibility, but overall suboptimal interobserver reproducibility for first-trimester fetal heart, lung, and kidney volume measurements using an innovative Virtual Reality approach. In the current stage, these measurements might be promising for the use in research settings. The reproducibility of the measurements might be further improved by novel post-processing algorithms.
Ultrasound in Obstetrics & Gynecology, Aug 25, 2014
The renal arteries normally arise from the abdominal aorta proximal to the bifurcation. Known ana... more The renal arteries normally arise from the abdominal aorta proximal to the bifurcation. Known anatomic variations in renal arteries, for example accessory renal arteries, are present in 20–30% of the general population and show different places of origin and various courses1. Accessory renal arteries are embryonic mesonephric arteries that failed to degenerate2. Accessory renal arteries may be parallel to the main renal arteries, this being the most common anatomic variation2. Other known variations include a divergent, convergent or crossed trajectory of the renal arteries on the same side1. We observed, in a fetus at 26 weeks’ gestation, two normal kidneys with bilateral accessory renal arteries. Three-dimensional (3D) power Doppler datasets were obtained using a GE Voluson E8 system (GE Medical Systems, Zipf, Austria). These datasets were analyzed in 4D view and by use of a virtual reality system to render images in the Barco I-space3. The Barco I-space is a CAVE-like virtual reality system, which, by use of the V-scope volume rendering application, creates a hologram from a 3D dataset. The hologram, projected onto the walls and floor of a dark room, is analyzed wearing 3D glasses and using a special joystick. By making use of the third dimension, ‘depth perception’, virtual reality enabled us to visualize the fetal vascular anatomy in more detail. The different kinds of voxels (3D pixels), i.e. power Doppler and gray-scale voxels, can easily be separated, allowing visualization of Doppler images of the fetal vasculature with and without the internal organs. The fetal vascular system, including the bilateral accessory renal arteries, is shown in Figure 1 as seen in 4D view and in Figure 2a as a hologram as seen in the Barco I-Space; Figure 2b is a schematic representation of Figure 2a. Visualization of three-dimensional images on a two-dimensional (2D) screen has technical limitations. In contrast to assessment in 4D view, the virtual reality
Objective: To demonstrate the use of a novel three-dimensional (3D) virtual reality (VR) system i... more Objective: To demonstrate the use of a novel three-dimensional (3D) virtual reality (VR) system in the visualization of first trimester growth and development in a case of confined placental trisomy 16 mosaicism (CPMþ16). Design: Case report. Setting: Prospective study on first trimester growth using a 3D VR system. Patient(s): A 34-year-old gravida 1, para 0 was seen weekly in the first trimester for 3D ultrasound examinations. Intervention(s): Chorionic villus sampling was performed because of an enlarged nuchal translucency (NT) measurement and low pregnancy-associated plasma protein-A levels, followed by amniocentesis. Result(s): Amniocentesis revealed a CPMþ16. On two-dimensional (2D) and 3D ultrasound no structural anomalies were found with normal fetal Dopplers. Growth remained below the 2.3 percentile. At 37 weeks, a female child of 2010 g (<2.5 percentile) was born. After birth, growth climbed to the 50th percentile in the first 2 months. Conclusion(s): The I-Space VR system provided information about phenotypes not obtainable by standard 2D ultrasound. In this case, the delay in growth and development could be observed very early in pregnancy. Since first trimester screening programs are still improving and becoming even more important, systems such as the I-Space open a new era for in vivo studies on the physiologic and pathologic processes involved in embryogenesis.
Background: Although numerous studies investigate sensory regeneration and reinnervation of the h... more Background: Although numerous studies investigate sensory regeneration and reinnervation of the hind paw of the rat after nerve damage, no comprehensive overview of its normal innervation is present in literature. The Evans Blue extravasation technique is a well-known technique to study patterns of skin innervation. This technique has been performed differently by various groups but was never used to study the entire skin innervation in rats' hind paw including all three branches of the sciatic nerve and the saphenous nerve in detail. Methods: In this paper, we have used the Evans Blue extravasation technique to chart the skin areas innervated by the sural, peroneal, tibial and/or saphenous nerves, which together innervate the entire hind paw of the rat, and use a new technique to analyze the distribution, overlap and variability of the results. The technique is based on analysis of whole hind paws using Optical Surface Mapping (OSM) in combination with the Computer Assisted Surgical Anatomy Mapping (CASAM) technology. Results: While the plantar hind paw is mainly innervated by the tibial nerve, the dorsal hind paw is supplied by the sural, peroneal and the saphenous nerve. Comparison with existint methods: Although our results basically concur with the general nerve-specific innervation of the rat hind paw, they show considerable detail in their areas of overlap as well as in the amount of variability between animals. Conclusions: These results will be invaluable to study and evaluate patterns of innervation and reinnervation of intact and damaged nerve fibers.
Ultrasound in Obstetrics & Gynecology, Aug 1, 2008
marker for Galloway Mowat syndrome. We further support the use of magnetic resonance imaging to a... more marker for Galloway Mowat syndrome. We further support the use of magnetic resonance imaging to assist in the characterization of fetal sulci and gyri in cases of prenatal suspected Galloway Mowat syndrome.
Originally the only way to look inside the human body without opening it up was by means of two d... more Originally the only way to look inside the human body without opening it up was by means of two dimensional (2D) images obtained using X-ray equipment. The fact that human anatomy is inherently three dimensional leads to ambiguities in interpretation and problems of occlusion. Three dimensional (3D) imaging modalities such as CT, MRI and 3D ultrasound remove these drawbacks and
In this study, a new 3-D Virtual Reality (3D VR) technique for examining placental and uterine va... more In this study, a new 3-D Virtual Reality (3D VR) technique for examining placental and uterine vasculature was investigated. The validity of placental bed vascular volume (PBVV) and fetal vascular volume (FVV) measurements was assessed and associations of PBVV and FVV with embryonic volume, crown-rump length, fetal birth weight and maternal parity were investigated. One hundred thirty-two patients were included in this study, and measurements were performed in 100 patients. Using V-Scope software, 100 3-D Power Doppler data sets of 100 pregnancies at 12 wk of gestation were analyzed with 3D VR in the I-Space Virtual Reality system. Volume measurements were performed with semi-automatic, pre-defined parameters. The inter-observer and intraobserver agreement was excellent with all intra-class correlation coefficients .0.93. PBVVs of multiparous women were significantly larger than the PBVVs of primiparous women (p 5 0.008). In this study, no other associations were found. In conclusion, V-Scope offers a reproducible method for measuring PBVV and FVV at 12 wk of gestation, although we are unsure whether the volume measured represents the true volume of the vasculature.
Is the maternal cardiovascular (CV) risk profile associated with human embryonic growth trajector... more Is the maternal cardiovascular (CV) risk profile associated with human embryonic growth trajectories and does the mode of conception affect this association? summary answer: This small study suggests that the maternal CV risk profile is inversely associated with first trimester embryonic growth trajectories in in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI) pregnancies, but not in spontaneously conceived pregnancies. what is known already: Maternal high-blood pressure and smoking affect placental function, accompanied by increased risk of fetal growth restriction and low-birthweight. Mothers who experience pregnancies complicated by fetal growth restriction are at increased risk of CV disease in later life. study design, size, duration: In a prospective periconception birth cohort conducted in a tertiary hospital, 111 singleton ongoing pregnancies with reliable pregnancy dating, no pre-existing maternal disease and no malformed live borns were investigated. participants/materials, settings, methods: Spontaneously conceived pregnancies with a reliable first day of the last menstrual period and a regular menstrual cycle of 25-31 days only (n ¼ 66) and IVF/ICSI pregnancies (n ¼ 45) were included. Women underwent weekly three-dimensional ultrasound scans (3D US) from 6-to 13-week gestational age. To estimate embryonic growth, serial crown-rump length (CRL) measurements were performed using the V-Scope software in a BARCO I-Space. Maternal characteristics and CV risk factors were collected by self-administered questionnaires. The CV risk profile was created based on a score of risk factors, including maternal age, body-mass index, CV disease in the family, diet and smoking. Quartiles of the CV risk score were calculated. Associations between the CV risk score and embryonic growth were assessed using square root transformed CRL in multivariable linear mixed model analyses. IVF/ICSI treatment in relation with CV risk factors substantiate the importance of more investigation into differences in sensitivity of endometrial, endothelial, placental and embryonic tissues.
Direct volume rendering algorithms are too computationally expensive to offer interactive frame r... more Direct volume rendering algorithms are too computationally expensive to offer interactive frame rates when rendering large 3D medical datasets on standard workstations. This article presents an image space parallelization of an image order volume rendering algorithm aimed at shared memory multiprocessors. This parallel implementation of direct volume rendering can significantly speed up rendering times and visualize 3D datasets with speeds of several frames per second. The algorithm was implemented and evaluated on Convex SPP Exemplar and SGI Challenge multiprocessors.
The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visual... more The aim of this study was to demonstrate that Carnegie Stages could be assigned to embryos visualized with a 3D virtual reality system. METHODS: We analysed 48 3D ultrasound scans of 19 IVF/ICSI pregnancies at 7-10 weeks' gestation. These datasets were visualized as 3D 'holograms' in the BARCO I-Space virtual reality system. Embryos were staged according to external morphological features (i.e. mainly limb development). After staging, the crown rump length (CRL) was measured. Stage and CRL were compared with gestational age based on the date of oocyte retrieval and with the classical data on embryology from the Carnegie Collection. RESULTS: Embryonic staging was relatively easy because the I-Space allows depth perception, which helps in the estimation of size and position. The presumed stages corresponded well with the measured CRL. However, in 28 out of 48 cases, the stages seemed to have been reached earlier than previously described for the Carnegie Collection. CONCLUSIONS: The I-Space, tentatively named Virtual Embryoscopy, is a promising non-invasive tool for early pregnancy evaluation. Combining embryonic growth with embryonic development opens a new area to study the relationship between embryonic growth, development and morphology, as well as second and third trimester pregnancy complications.
Ultrasound in Obstetrics & Gynecology, Sep 21, 2007
17th World Congress on Ultrasound in Obstetrics and Gynecology Oral poster abstracts signs. This ... more 17th World Congress on Ultrasound in Obstetrics and Gynecology Oral poster abstracts signs. This has proven to predict CA with a high degree of accuracy when compared to placental histology. We aimed to investigate whether scans in earlier pregnancy can be used to diagnose CA with similar reliability. Methods: This was a retrospective study of twin pregnancies over a three-year period. Women with viable twin pregnancies who underwent a transvaginal scan (TVS) between 7 and 9 weeks of gestation were included in the analysis, and CA documented. This was compared to the respective diagnoses of CA at the 11-14 week scan. CA at the 11-14 week scan was assumed to be diagnostic, given the previously reported high sensitivity and specificity. Results: 69 women with viable twin pregnancies between 7 and 9 weeks also attended for an 11-14 week scan at our hospital. In five women spontaneous single fetal demise occurred between scans and were excluded. Of the remaining twins, CA was documented in 58 cases at 7-9 weeks. Overall, there was agreement in CA between the two scans in 55 of these 58 (94.8%). Agreement was highest for dichorionic-diamniotic (DCDA) pregnancies at 7-9 weeks: 44/45 (97.8%) were confirmed as DCDA and 1 (2.2%) as monochorionic-diamniotic (MCDA) at the 11-14 week scan. Of the 11 MCDA pregnancies at 7-9 weeks, 10 (90.9%) were found to be MCDA and one (9.1%) DCDA. There were two monochorionic-monoamniotic (MCMA) pregnancies diagnosed at 7-9 weeks, of which one was subsequently found to be MCMA while the other was MCDA. Conclusions: TVS at 7-9 weeks will correctly diagnose CA in about 95% of twin pregnancies. Accuracy may be higher for DCDA twins than MCDA twins and this may relate to the gestation at which sonographic appearance of the amniotic sac occurs.
Ultrasound in Obstetrics & Gynecology, Sep 1, 2012
The automated method showed accurate prediction of the manually labelled planes with an average s... more The automated method showed accurate prediction of the manually labelled planes with an average sensitivity of 91.29% and a positive predictive value of 76.29%. Through closer inspection, all false positive planes selected by the automated method contained both the SB and UV in the correct position but had not been selected by the expert because of stricter criteria imposed. Conclusions: Our results show that machine learning can be used to automatically select a correct AC plane from a fetal 3D volume, and is an early first step in the direction of automated fetalsonography. Such an automated method has the potential for reducing the time needed to complete an ultrasound examination or to perform offline examinations. Further work will be needed to evaluate this and to extend it to other areas of fetal biometry.
In this chapter we take a look at the possible applications of volume visualization in immersive ... more In this chapter we take a look at the possible applications of volume visualization in immersive virtual environments, and how they can be implemented. Nowadays, the availability of many kinds of 3D imaging modalities, like CT, MRI and 3D ultrasound, gives clinicians an unprecedented ability to look inside a patient without the need to operate. However, while these datasets are three dimensional, they are still presented on 2D (flat) screens. While most systems and workstations offer a volume rendering option to present the data, when projected onto a normal screen (or printed on paper or film), the images are not truly 3D and are often termed “2.5D.” By using a virtual reality system that immerses the viewer(s) in a truly three-dimensional world, we hope to improve the understanding of these images.
Welcome to the 2001 IEEE Symposium on Parallel and Large Data Visualization and Graphics (PVG2001... more Welcome to the 2001 IEEE Symposium on Parallel and Large Data Visualization and Graphics (PVG2001). This year's proceedings are dominated by scientific applications of parallel visualization, a subject that will be explored in the panel discussion. Other noticeable trends this year are the increasing prevalence of PC graphics clusters and the use of out-of-core techniques as alternatives to traditional parallelism. The following are summary descriptions of the program presentations. KEYNOTE ADDRESS In keeping with this year's theme of "large data" our invited keynote address is by the research staff at Celera Genomics Corporation. This contribution (with 14 co-authors) describes their experiences developing and using visualization tools during the process of mapping the human genome, and forward-looking challenges in the emerging field of proteomics. We believe this discussion is timely and hope it will lead to future work in these areas. VECTOR FIELD VISUALIZATION This set of papers presents three approaches to visualizing vector fields produced by large simulations of three dimensional fluids. Cruz, Godoy, Garcia & Ramos devise a technique that captures the surface deformations of a flow field over time. The technique makes visible the stretching and folding that characterizes fluid mixing, and is demonstrated on a cluster of commodity PCs and on an SGI Origin. Crossno, Angel & Munich compare three fast methods for mapping 3D vectors into color space, and apply the methods to visualizing an ocean circulation model. The methods exploit human psychophysical properties to maximize the efficiency of the color encoding. Bruckschen, Kuester, Hamann & Joy explore real time out-of-core particle tracing for large time varying vector fields. Their system runs on a commodity PC running Linux equipped with a RAID. SURFACES AND PARALLEL RENDERING This eclectic session begins with a paper by Dey, Giesen & Hudson that presents a Delaunay based surface reconstruction algorithm for creating polygonal models from a very large number of sample points. They employ a divide-and-conquer strategy in order to minimize memory usage. With their new method it is now possible to reconstruct a surface from one million points on a modest PC. Reinhard, Shirley & Hansen describe a parallel point projection method that may be used to increase image size and scene complexity during interactive ray tracing. They have created a parallel Render Cache and have applied it to the concept of frameless rendering. The next two papers explore parallel rendering on PC clusters. Samanta, Funkhauser & Li have developed a K-way replication scheme that distributes each 3D primitive of a scene to only K number of PCs in a rendering cluster. They show that parallel rendering efficiencies produced with small replication factors are similar to ones using full replication. Moreland, Wylie & Pavlakos present a scalable, sort-last parallel rendering system running on a PC cluster that is capable of rendering extremely large geometric models onto high-resolution tile displays. They exploit the spatial coherency of their data in order to render 120 million triangles/second on a 12 megapixel display. SOFTWARE INFRASTRUCTURE FOR PARALLEL VISUALIZATION In this session two frameworks are presented for visualizing large datasets. The first paper by Law, Henderson & Ahrens is a case study describing the use of the well-known Visualization Toolkit (VTK) software for rendering large datasets, with an application to ocean current simulations. The second paper by Bartz, Staneker, Strasser, Cripe, Gaskins, Orton, Carter, Johannsen & Trom describes the Open Source "Jupiter" toolkit, and new occlusion culling extensions for interactively rendering very large polygonal models like those typically generated by CAD-packages. ARCHITECTURES FOR STRUCTURED VOLUME RENDERING This session presents two architectures for ray-casting structured volume datasets. MeiBner, Grimm, StraBer, Packer & Latimer present an implementation of a parallel ray-casting algorithm on a new single-chip SIMD architecture. Concurrent ray-processing is scheduled to produce efficient memory access and the ray-casting algorithm is mapped onto the architecture to avoid floating point calculations. Lombeyda, Mall, Shand, Breen & Heirich describe a PC cluster architecture utilizing SEPIA and Volume Protechnology that is capable of interactively rendering large data volumes. The architecture uses dynamically-mapped associative blending operators in a sort-last configuration to merge streams of images of subvolumes rendered on separate PCs into a single stream in real-time. PANEL - PARALLELISM: RENDERING, VISUALIZATION AND LARGE DATA The focus of this symposium has evolved over the years. The symposium began in 1993 as the Parallel Rendering Symposium (PRS) and primarily focused on parallel photorealistic rendering issues. In 1999 the symposium was expanded to include parallel volume visualization and changed its…
This paper presents the work that has been carried out at SARA on various projects that use volum... more This paper presents the work that has been carried out at SARA on various projects that use volume rendering techniques to explore 3D (i.e., volumetric) datasets in the CAVE virtual reality environment. The stereoscopic, large-format images of the CAVE offer insights into the data that a normal rendering viewed on a monitor does not. After evaluating the few existing volume rendering programs available for the CAVE, we concluded that we needed to develop our own software, if we wanted an up-to-date, robust, and extensible application. Because our CAVE is driven by a high-end Silicon Graphics computer, the use of a (hardware assisted) 3D texture-mapping algorithm is the most obvious choice. With this algorithm, interactive framerates can be obtained, which is essential for use in a VR environment. We have used the resulting software, dubbed CAVORE for CAve VOlume REndering, to explore both medical and biological datasets and are extending it with new options as required by the ongoing projects.
Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed AC... more Background and purpose Non-anatomic bone tunnel placement is the most common cause of a failed ACL reconstruction. Accurate and reproducible methods to visualize and document bone tunnel placement are therefore important. We evaluated the reliability of standard radiographs, CT scans, and a 3-dimensional (3D) virtual reality (VR) approach in visualizing and measuring ACL reconstruction bone tunnel placement. Methods 50 consecutive patients who underwent single-bundle ACL reconstructions were evaluated postoperatively by standard radiographs, CT scans, and 3D VR images. Tibial and femoral tunnel positions were measured by 2 observers using the traditional methods of Amis, Aglietti, Hoser, Stäubli, and the method of Benereau for the VR approach. Results The tunnel was visualized in 50-82% of the standard radiographs and in 100% of the CT scans and 3D VR images. Using the intraclass correlation coefficient (ICC), the inter-and intraobserver agreement was between 0.39 and 0.83 for the standard femoral and tibial radiographs. CT scans showed an ICC range of 0.49-0.76 for the inter-and intraobserver agreement. The agreement in 3D VR was almost perfect, with an ICC of 0.83 for the femur and 0.95 for the tibia. Interpretation CT scans and 3D VR images are more reliable in assessing postoperative bone tunnel placement following ACL reconstruction than standard radiographs.
Ultrasound in Obstetrics & Gynecology, Aug 1, 2016
. This study compared measurements of levator ani hiatal volume during rest and on maximum Valsal... more . This study compared measurements of levator ani hiatal volume during rest and on maximum Valsalva, obtained using conventional three-dimensional (3D) translabial ultrasound and virtual reality imaging. Our objectives were to establish their agreement and reliability, and their relationship with prolapse symptoms and POP quantification (POP-Q) stage. Methods One hundred women with an intact levator ani were selected from our tertiary clinic database. Information on clinical symptoms were obtained using standardized questionnaires. Ultrasound datasets were analyzed using a rendered volume with a slice thickness of 1.5 cm, at the level of minimal hiatal dimensions, during rest and on maximum Valsalva. The levator area (in cm 2 ) was measured and multiplied by 1.5 to obtain the levator ani hiatal volume (in cm 3 ) on conventional 3D ultrasound. Levator ani hiatal volume (in cm 3 ) was measured semi-automatically by virtual reality imaging using a segmentation algorithm. Twenty patients were chosen randomly to analyze intra-and interobserver agreement. The mean difference between levator hiatal volume measurements on 3D ultrasound and by virtual reality was 1.52 cm 3 (95% CI, 1.00-2.04 cm 3 ) at rest and 1.16 cm 3 (95% CI, 0.56-1.76 cm 3 ) during maximum Valsalva (P < 0.001). Both intra-and interobserver intraclass correlation coefficients were ≥ 0.96 for conventional
Journal of Obstetrics and Gynaecology Research, Jan 29, 2022
Introduction: To investigate the reproducibility of first-trimester fetal organ volume measuremen... more Introduction: To investigate the reproducibility of first-trimester fetal organ volume measurements using three-dimensional (3D) ultrasound and a Virtual Reality system. Methods: Within a population-based prospective cohort study, 3D ultrasound datasets of 25 first-trimester fetuses were collected by three sonographers. We used the V-scope application to perform Virtual Reality volume assessments of the fetal heart, lungs, and kidneys. All measurements were performed by two independent researchers. Results: Intraobserver analyses for volume measurements of the fetal heart, lungs, and kidneys showed intraclass correlation coefficients ≥0.86, mean differences ≤8.3%, and coefficients of variation ≤22.8%. Interobserver analyses showed sufficient agreement for right lung volume measurements, but consistent measurement differences between observers for left lung, heart, and kidney volume measurements (p-values <0.05). Conclusion: We observed sufficient intraobserver reproducibility, but overall suboptimal interobserver reproducibility for first-trimester fetal heart, lung, and kidney volume measurements using an innovative Virtual Reality approach. In the current stage, these measurements might be promising for the use in research settings. The reproducibility of the measurements might be further improved by novel post-processing algorithms.
Ultrasound in Obstetrics & Gynecology, Aug 25, 2014
The renal arteries normally arise from the abdominal aorta proximal to the bifurcation. Known ana... more The renal arteries normally arise from the abdominal aorta proximal to the bifurcation. Known anatomic variations in renal arteries, for example accessory renal arteries, are present in 20–30% of the general population and show different places of origin and various courses1. Accessory renal arteries are embryonic mesonephric arteries that failed to degenerate2. Accessory renal arteries may be parallel to the main renal arteries, this being the most common anatomic variation2. Other known variations include a divergent, convergent or crossed trajectory of the renal arteries on the same side1. We observed, in a fetus at 26 weeks’ gestation, two normal kidneys with bilateral accessory renal arteries. Three-dimensional (3D) power Doppler datasets were obtained using a GE Voluson E8 system (GE Medical Systems, Zipf, Austria). These datasets were analyzed in 4D view and by use of a virtual reality system to render images in the Barco I-space3. The Barco I-space is a CAVE-like virtual reality system, which, by use of the V-scope volume rendering application, creates a hologram from a 3D dataset. The hologram, projected onto the walls and floor of a dark room, is analyzed wearing 3D glasses and using a special joystick. By making use of the third dimension, ‘depth perception’, virtual reality enabled us to visualize the fetal vascular anatomy in more detail. The different kinds of voxels (3D pixels), i.e. power Doppler and gray-scale voxels, can easily be separated, allowing visualization of Doppler images of the fetal vasculature with and without the internal organs. The fetal vascular system, including the bilateral accessory renal arteries, is shown in Figure 1 as seen in 4D view and in Figure 2a as a hologram as seen in the Barco I-Space; Figure 2b is a schematic representation of Figure 2a. Visualization of three-dimensional images on a two-dimensional (2D) screen has technical limitations. In contrast to assessment in 4D view, the virtual reality
Objective: To demonstrate the use of a novel three-dimensional (3D) virtual reality (VR) system i... more Objective: To demonstrate the use of a novel three-dimensional (3D) virtual reality (VR) system in the visualization of first trimester growth and development in a case of confined placental trisomy 16 mosaicism (CPMþ16). Design: Case report. Setting: Prospective study on first trimester growth using a 3D VR system. Patient(s): A 34-year-old gravida 1, para 0 was seen weekly in the first trimester for 3D ultrasound examinations. Intervention(s): Chorionic villus sampling was performed because of an enlarged nuchal translucency (NT) measurement and low pregnancy-associated plasma protein-A levels, followed by amniocentesis. Result(s): Amniocentesis revealed a CPMþ16. On two-dimensional (2D) and 3D ultrasound no structural anomalies were found with normal fetal Dopplers. Growth remained below the 2.3 percentile. At 37 weeks, a female child of 2010 g (<2.5 percentile) was born. After birth, growth climbed to the 50th percentile in the first 2 months. Conclusion(s): The I-Space VR system provided information about phenotypes not obtainable by standard 2D ultrasound. In this case, the delay in growth and development could be observed very early in pregnancy. Since first trimester screening programs are still improving and becoming even more important, systems such as the I-Space open a new era for in vivo studies on the physiologic and pathologic processes involved in embryogenesis.
Background: Although numerous studies investigate sensory regeneration and reinnervation of the h... more Background: Although numerous studies investigate sensory regeneration and reinnervation of the hind paw of the rat after nerve damage, no comprehensive overview of its normal innervation is present in literature. The Evans Blue extravasation technique is a well-known technique to study patterns of skin innervation. This technique has been performed differently by various groups but was never used to study the entire skin innervation in rats' hind paw including all three branches of the sciatic nerve and the saphenous nerve in detail. Methods: In this paper, we have used the Evans Blue extravasation technique to chart the skin areas innervated by the sural, peroneal, tibial and/or saphenous nerves, which together innervate the entire hind paw of the rat, and use a new technique to analyze the distribution, overlap and variability of the results. The technique is based on analysis of whole hind paws using Optical Surface Mapping (OSM) in combination with the Computer Assisted Surgical Anatomy Mapping (CASAM) technology. Results: While the plantar hind paw is mainly innervated by the tibial nerve, the dorsal hind paw is supplied by the sural, peroneal and the saphenous nerve. Comparison with existint methods: Although our results basically concur with the general nerve-specific innervation of the rat hind paw, they show considerable detail in their areas of overlap as well as in the amount of variability between animals. Conclusions: These results will be invaluable to study and evaluate patterns of innervation and reinnervation of intact and damaged nerve fibers.
Ultrasound in Obstetrics & Gynecology, Aug 1, 2008
marker for Galloway Mowat syndrome. We further support the use of magnetic resonance imaging to a... more marker for Galloway Mowat syndrome. We further support the use of magnetic resonance imaging to assist in the characterization of fetal sulci and gyri in cases of prenatal suspected Galloway Mowat syndrome.
Originally the only way to look inside the human body without opening it up was by means of two d... more Originally the only way to look inside the human body without opening it up was by means of two dimensional (2D) images obtained using X-ray equipment. The fact that human anatomy is inherently three dimensional leads to ambiguities in interpretation and problems of occlusion. Three dimensional (3D) imaging modalities such as CT, MRI and 3D ultrasound remove these drawbacks and
In this study, a new 3-D Virtual Reality (3D VR) technique for examining placental and uterine va... more In this study, a new 3-D Virtual Reality (3D VR) technique for examining placental and uterine vasculature was investigated. The validity of placental bed vascular volume (PBVV) and fetal vascular volume (FVV) measurements was assessed and associations of PBVV and FVV with embryonic volume, crown-rump length, fetal birth weight and maternal parity were investigated. One hundred thirty-two patients were included in this study, and measurements were performed in 100 patients. Using V-Scope software, 100 3-D Power Doppler data sets of 100 pregnancies at 12 wk of gestation were analyzed with 3D VR in the I-Space Virtual Reality system. Volume measurements were performed with semi-automatic, pre-defined parameters. The inter-observer and intraobserver agreement was excellent with all intra-class correlation coefficients .0.93. PBVVs of multiparous women were significantly larger than the PBVVs of primiparous women (p 5 0.008). In this study, no other associations were found. In conclusion, V-Scope offers a reproducible method for measuring PBVV and FVV at 12 wk of gestation, although we are unsure whether the volume measured represents the true volume of the vasculature.
Is the maternal cardiovascular (CV) risk profile associated with human embryonic growth trajector... more Is the maternal cardiovascular (CV) risk profile associated with human embryonic growth trajectories and does the mode of conception affect this association? summary answer: This small study suggests that the maternal CV risk profile is inversely associated with first trimester embryonic growth trajectories in in vitro fertilization (IVF)/intra-cytoplasmic sperm injection (ICSI) pregnancies, but not in spontaneously conceived pregnancies. what is known already: Maternal high-blood pressure and smoking affect placental function, accompanied by increased risk of fetal growth restriction and low-birthweight. Mothers who experience pregnancies complicated by fetal growth restriction are at increased risk of CV disease in later life. study design, size, duration: In a prospective periconception birth cohort conducted in a tertiary hospital, 111 singleton ongoing pregnancies with reliable pregnancy dating, no pre-existing maternal disease and no malformed live borns were investigated. participants/materials, settings, methods: Spontaneously conceived pregnancies with a reliable first day of the last menstrual period and a regular menstrual cycle of 25-31 days only (n ¼ 66) and IVF/ICSI pregnancies (n ¼ 45) were included. Women underwent weekly three-dimensional ultrasound scans (3D US) from 6-to 13-week gestational age. To estimate embryonic growth, serial crown-rump length (CRL) measurements were performed using the V-Scope software in a BARCO I-Space. Maternal characteristics and CV risk factors were collected by self-administered questionnaires. The CV risk profile was created based on a score of risk factors, including maternal age, body-mass index, CV disease in the family, diet and smoking. Quartiles of the CV risk score were calculated. Associations between the CV risk score and embryonic growth were assessed using square root transformed CRL in multivariable linear mixed model analyses. IVF/ICSI treatment in relation with CV risk factors substantiate the importance of more investigation into differences in sensitivity of endometrial, endothelial, placental and embryonic tissues.
Uploads
Papers by Anton Koning