This document discusses 3D ultrasound technology and its applications in obstetrics. It provides a brief history of ultrasound development and explains how 3D ultrasound works, involving scanning, reconstruction, and visualization of 2D images into a 3D volume. The document then discusses several common congenital anomalies such as spina bifida and cleft lip that can be better detected using 3D ultrasound compared to 2D. Studies show 3D ultrasound improves diagnosis of fetal abnormalities from 79% to 94% compared to 2D ultrasound alone. 3D ultrasound also strengthens the maternal-fetal bonding process by providing more recognizable images of the fetus.

1. Lindsay Meyer
(Dianna Zosche)
Three-dimensional Ultrasound:
Techniques and Applications in Obstetrics
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Abstract
Ultrasound has been used in medicine for over half a century, and is recognized as a non-
invasive, non-radiative, and inexpensive imaging modality. Three-dimensional (“3D”)
medical imaging is now being widely employed in the clinical setting. This report
reviews the development of ultrasound, its method of function, and its practical
applications of 3D ultrasound in fetal embryology and obstetrics.

2. Lindsay Meyer
(Dianna Zosche)
Introduction
“Ultrasound” is the vernacular term for medical sonography, a non-invasive imaging
technique used in diagnosing disease and developmental defects. In physics, “ultrasound” refers
to acoustic energy outside the range of human hearing. Medical sonographic scanners typically
operate between two and 18 megahertz, with a unique relationship between resolution and depth.
Lower frequencies penetrate body tissues deeper than higher frequencies, but produce lower
image resolution (and vice-versa). The improving economics of 3D ultrasound technology
coupled with advances in 3D image visualization have made the technique increasingly routine
for pregnant women in the past decade.
This paper is meant to achieve two goals. First, an exploration of the origin of ultrasound
will provide the basis for building a compelling case for the use of 3D ultrasound. Second, a
discussion of common congenital anomalies will illustrate the efficacy of the technology.
A Brief History of Ultrasound
In 1950, the first commercial “ultrasonic locator” became available by General Precision
Laboratories (Woo, 2002). George Ludwig, a Naval Officer in Bethesda, Maryland first began
experimenting with the conduction of pulse-echo techniques several years prior. His
methodology was similar to the radar utilized by the military to detect the presence of foreign
boats or flying objects. Ludwig collaborated with physicists and engineers to study gallstones in
muscle tissues in the human body. Using a transducer to send and receive high-frequency sound
waves at a rate of 60 pulses per second, Ludwig recorded reflections with an oscilloscope to
detect the presence and position of foreign bodies. Much of this early work with ultrasound was
clandestine until 1949 because the information was considered classified naval information.
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3. Lindsay Meyer
(Dianna Zosche)
From 2D to 3D – Imaging Techniques
Conventional, 2D ultrasound relies on the reflection of high frequency sound waves by
bones and muscles. Soft tissue and hollow structures do not reflect the waves and appear dark.
Anywhere there are changes in density in the body, sound waves are generally reflected. This
technology was prevalent around the world for nearly half a century.
In 1994, 3D ultrasound was popularized in the European Journal of Ultrasound and
detailed three discrete steps – scanning, reconstruction, and visualization. Four scanning
techniques (mechanical, free-hand with position sensing, free-hand without position sensing, 2D
array) exist. Among these methods, mechanical scanning is most relevant to medicine because
the relative position and orientation of each image can be known precisely. This approach uses a
scanning apparatus (transducer) to acquire 2D ultrasound images over the area of interest
(Fenster, Downey & Cardinal, 2000).
In the reconstruction step, 2D images are placed in their correct relative positions and
orientations in the 3D image volume (Fenster et al., 2002). Feature-based reconstruction uses
anatomical structures to determine boundary surfaces, offering efficient manipulation by
computer. In contrast, the more popular voxel method of reconstruction uses a Cartesian grid to
build elements in three dimensions. Each 2D coordinate (x, y) is interpolated to determine a 3D
coordinate (x, y, z). Automated reference tables stored in computers help accelerate this process.
The voxel approach preserves all original information and enables the generation of new views
not in the original set of 2D images. This method is also superior because it allows the operator
to use different segmentation and classification schemes to segment boundaries, measure volume
or perform various volume-based rendering (Fenster et al., 2000).
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4. Lindsay Meyer
(Dianna Zosche)
The third and final step to 3D ultrasound is visualization. For optimal image perception,
depth shading and color and texture mapping is used. Volume rendering helps to approximate
the passage of light through soft tissues. Computer algorithms have vastly simplified this
process of manipulating and isolating images. Dynamic 3D imaging is used to show fluid
motion within the fetus and is a consequence of continued technological improvements.
12/9/2007 4:21 PMMedical Physics Presentation © 9
Scan
 Uses traditional
2D apparatus
(transducer)
 Acquires a series
of 2D images
 Real-time, fast
acquisition
 Computer
integrates 2D
images into 3D
volume
 Computer
matches 2D and
3D coordinates
Reconstruct
 Images are
colored and
shaded
 Manipulation of
image; isolation of
structures
 Dynamic 3D
imaging (4D)
Visualize
Building a Case for 3D Ultrasound
In conventional, two-dimensional (2D) ultrasounds, physicians were left to mentally
integrate multiple 2D images to understand 3D structures. This guesswork introduced a high
margin of error in addition to prohibiting the imaging of certain anatomical features. As 2D
ultrasounds capture images at randomized planes, generating the same picture more than once is
nearly impossible (Fenster et al., 2000). This impedes effective therapeutic monitoring. It also
increases the risk of incorrect diagnosis. Systematically assessing fetal development is
compromised in 2D ultrasound because accurate volume estimations are difficult to make. Each
of these obstacles was overcome with the development of 3D ultrasound.
Page 4 of 11

5. Lindsay Meyer
(Dianna Zosche)
Common Congenital Anomalies
Embryology texts suggest the incidence of birth defects to be approximately 5%. For the
purposes of this paper, common congenital anomalies have been classified into four groups –
those of the body surface, extremities, spine, and cranium/face. The development of 3D
ultrasound has improved the detection of several anomalies in each of these four groups (Xu et
al, 2002).
Conjoined twins, tumors, edema, and placental defects are
abnormalities of the body surface. Difficult to detect and diagnose,
these conditions vary in severity. Teratomas result from the
unregulated division of pluripotent (stem) cells. Sacrococcogeal
teratomas appear at the base of the tailbone and are the most common
type of tumor in newborns. These teratomas can obstruct the normal
passage of fluids from surrounding organs. Placental defects include
placental previa (placenta impedes the cervix) and placental abruption (placental lining separates
from the uterus). Often fatal to infant and mother, these conditions are associated with heavy
bleeding late in pregnancy and require careful monitoring.
Poldactyly, a condition in which too few or too many fingers or
toes develop is a common defect of the extremities caused by genetic
mutation. It may also occur as part of a cluster of defects related to
teratogen-induced syndromes (i.e.: fetal alcohol syndrome, Accutane-
exposure). Other defects to the extremities include stunted growth
(osteogenesis imperfecta) and club foot. This class of defects is not
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12/9/20076:54PMMedicalPhysicsPresentation© 6
RepresentativeMedicalCases
Commoncongenitalanomalies
BodySurface
Conjoinedtwins
Tumors
Edema
Placentaldefects
Extremities
Polydactyly
Limbdefects
Osteogenesis
imperfecta
Clubfoot
Spine
Spinabifida
Scoliosis
Neuraltube
defects
Cranium/Face
Cleftlip
Cleftpalate
Hydrocephalus
Anencephaly
12/9/20076:55PMMedicalPhysicsPresentation© 6
RepresentativeMedicalCases
Commoncongenitalanomalies
BodySurface
Conjoinedtwins
Tumors
Edema
Placentaldefects
Extremities
Polydactyly
Limbdefects
Osteogenesis
imperfecta
Clubfoot
Spine
Spinabifida
Scoliosis
Neuraltube
defects
Cranium/Face
Cleftlip
Cleftpalate
Hydrocephalus
Anencephaly

6. Lindsay Meyer
(Dianna Zosche)
considered life-threatening and occurs in 1-2 live births per 1000, with a higher incidence in
males.
Spina bifida is a condition in which the neural tube does not
close. While surgery can correct the opening, affected individuals will
experience reduced quality of life due to nerve and spinal cord
dysfunction. Some fetuses with the condition will spontaneously abort.
Research by Kurjak, Pooh, Merce, Carrera, Salihagic-Kadic &
Andonotopo (2005) suggested that the condition could be diagnosed
with 3D ultrasound at 9 weeks gestation. In addition to neural tube defects, scoliosis can also be
diagnosed with 3D ultrasound.
Environmental influences such as maternal retinoid intake and
cigarette smoking may interact with genetics to cause cleft lip and cleft
palate. Hydrocephalus is caused by an accumulation of cerebrospinal
fluid and manifests in an abnormally large head. The defect occurs in
approximately one of every 500 live births and is more common than
Down syndrome. Anencephaly is a disorder in which infants are born
without a forebrain. If spontaneous abortion or stillbirth does not occur,
death occurs shortly after delivery.
Applications
Study data released by Xu, Zhang, Lu & Ziao in 2002 compared the efficacy of 2D and
3D ultrasounds on the basis of accurate diagnosis of prenatal malformations. For the four
categories of congenital anomalies outlined above, the study showed diagnostic superiority with
Page 6 of 11
12/9/20076:54PMMedicalPhysicsPresentation© 6
RepresentativeMedicalCases
Commoncongenitalanomalies
BodySurface
Conjoinedtwins
Tumors
Edema
Placentaldefects
Extremities
Polydactyly
Limbdefects
Osteogenesis
imperfecta
Clubfoot
Spine
Spinabifida
Scoliosis
Neuraltube
defects
Cranium/Face
Cleftlip
Cleftpalate
Hydrocephalus
Anencephaly
12/9/20077:11PMMedicalPhysicsPresentation© 6
RepresentativeMedicalCases
Commoncongenitalanomalies
BodySurface
Conjoinedtwins
Tumors
Edema
Placentaldefects
Extremities
Polydactyly
Limbdefects
Osteogenesis
imperfecta
Clubfoot
Spine
Spinabifida
Scoliosis
Neuraltube
defects
Cranium/Face
Cleftlip
Cleftpalate
Hydrocephalus
Anencephaly

7. Lindsay Meyer
(Dianna Zosche)
3D ultrasound. The study made a definitive diagnosis of 79% of defects with 2D ultrasound (n =
49). The use of 3D ultrasound improved the percentage of correct diagnoses to 94% (n = 58). In
60% of cases (n = 35), malformations were correctly diagnosed by both 2D and 3D ultrasound
but the use of 3D ultrasound provided better qualitative diagnostic information. Extrapolating
this 15% improvement in correct diagnoses to larger populations suggests a cascade of public
health benefits associated with early detection of defects and improved prenatal care.
Aggregating data from the Xu et al. (2002) study demonstrated that detection of
craniofacial anomalies was 19% greater with 3D ultrasound (n = 30). No apparent difference
between ultrasound modalities for the body surface (n = 26) reflects the reality that diagnosing
these defects in utero can be extremely challenging. This study also left out conjoined twins, a
rare abnormality, but one that is easily detected with 3D ultrasound. All spinal defects were
detected with 3D ultrasound, but the low sample size (n =4) may overstate the comparative
diagnostic usefulness of 3D technology. Low sample size (n = 2) was also encountered with
defects to the extremities, reducing the integrity of the suggested 50% improvement in diagnosis
with 3D ultrasound.
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8. Lindsay Meyer
(Dianna Zosche)
Comparitive Diagnosis of Prenatal Malformations
69%
0%
50%
97%
88%
100%
100%
97%
0% 20% 40% 60% 80% 100%
Cranium/face
Spine
Extremities
Body surface
% of correct diagnoses (2D) % of correct diagnoses (3D)
Kurjak et al. (2005) showed that structural and functional developments in the first 12
weeks of gestation could be assessed more objectively and reliably with 3D ultrasound. Because
the first trimester presents the greatest risk of developmental abnormalities, accurate fetal
monitoring during this period is critical. The anatomy and physiology of embryonic
development is a field where medicine exerts its greatest impact on early pregnancy and is a
foray into fascinating aspects of embryonic differentiation (Kurjak et al., 2005).
Dyson, Pretorius, Budorick, Johnson, Skylansky, Cantrell, et al. (2000) suggested that 3D
images were useful in counseling patients about the severity of fetal abnormalities. Dyson et al.
also determined that the level of diagnostic confidence was heightened and used to support
diagnoses made on the basis of 2D ultrasound images.
Clinical Correlates
Page 8 of 11

9. Lindsay Meyer
(Dianna Zosche)
In addition to improved detection of prenatal malformations, 3D ultrasound has provided
an unintended benefit by strengthening the maternal-fetal bonding process. Ji, Pretorius,
Newton, Uyans, Hull, Hollenbach et al. (2004) found that mothers who received 3D ultrasound
showed their ultrasound images to more people than mothers receiving 2D ultrasounds alone.
Seventy percent of mothers who had 3D ultrasounds felt that they “knew” their baby
immediately after birth versus 56% of mothers that had 2D ultrasounds, reflecting the fact that
82% of mothers who had 3D ultrasounds had a tendency to form a mental picture of their child,
post-examination. This contrasts with the 39% of subjects who began to picture their infant after
having a 2D ultrasound. Image quality of 2D ultrasounds has improved but most laypersons are
not equipped to understand even the highest resolution 2D images. Three-dimensional
ultrasounds produce more recognizable images, improving the maternal-fetal bonding process.
Conclusion
As medicine continues to evolve, imaging techniques will concurrently improve to
address the challenges of modern science. The advent of 3D ultrasound technology represents
one giant leap for medical imaging. Three-dimensional ultrasound provides accurate
representation of internal structures and improved visualization capacity. By integrating
traditional 2D imaging techniques with 3D ultrasound, clinicians improve the statistical
probability of accurate diagnoses. Detection of congenital anomalies affords parents and
physicians substantial latitude in formulating and implementing prenatal care regiments, thereby
improving public health.
The prevalence of 3D ultrasound in obstetric exams is increasing as the technology
becomes more cost-effective. As this trend continues, it offers the potential for safe, non-
invasive monitoring of fetal development. Drawing attention to 3D ultrasound and its medical
Page 9 of 11

10. Lindsay Meyer
(Dianna Zosche)
applications helps perpetuate awareness of its inherent diagnostic value. Assessing the value of
3D ultrasound encourages economic investment in improved medical technologies and propels
continued innovation, raising standards of care.
Page 10 of 11

11. Lindsay Meyer
(Dianna Zosche)
References
Dyson, R., Pretorius, D., Budorick, N., Johnson, D., Sklansky, M., Cantrell, C., et al. (2000).
Three-dimensional ultrasound in the evaluation of fetal anomalies. Ultrasound in
Obstetrics and Gynecology, 16, 321-28.
Fenster, A., Downey, D., Cardinal, H. (2001). Three-dimensional ultrasound imaging. Physics
in Medicine and Biology, 46, R67-99.
Ji, E., Pretorius, D., Newton, R., Uyan, K., Hull, A., Hollenbach, K. et al. (2005). Effects of
ultrasound on maternal-fetal bonding: a comparison of two- and three-dimensional
imaging. Ultrasound in Obstetrics and Gynecology, 25, 473-77.
Kurjak, A., Pooh, R., Merce, L., Carrera, J., Salihagic-Kadic, A. & Andonotopo, W. (2005).
Structural and functional early human development assessed by three-dimensional and
four-dimensional sonography. Fertility and Sterility, 84(5), 1285-1299.
Medical ultrasonography. (2007, December 7). In Wikipedia, The Free Encyclopedia.
Retrieved December 9, 2007, from http://en.wikipedia.org/w/index.php?
title=Medical_ultrasonography&oldid=176296551
Woo, Joseph (2002). A short history of the development of ultrasound in obstetrics and
gynecology. http://www.ob-ultrasound.net/history1.html
Xu, H., Zhang, Q., Lu, M., Xiao, X. (2002). Comparison of two-dimensional and three-
dimensional sonography in evaluating fetal malformations. Journal of Clinical
Ultrasound, 30, 515-25.
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