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Chapter 38
Three-Dimensional Doppler Ultrasound in Gynecology
Ivica Zalud, Lawrence D. Platt
Three-dimensional (3D) reconstruction of ultrasound
images was first demonstrated nearly 15 years ago
but only now is becoming a clinical reality. In the
meantime, methods for 3D reconstruction of computed
tomography (CT) and magnetic resonance
imaging (MRI) have achieved an advanced state of
development, and 3D imaging with these modalities
has been applied widely in clinical practice. Three-dimensional
applications in ultrasound have lagged behind
CT and MRI, because ultrasound data is much
more difficult to render in 3D, for a variety of technical
reasons, than either CT or MRI data. Only in the
past few years has the computing power of ultrasound
equipment reached a level adequate enough for
the complex signal processing tasks needed to render
ultrasound data in three dimensions. Within the past
years several new ultrasound techniques have appeared.
Three-dimensional ultrasound scanning, in
which there has been great interest, is one of them
[1]. Especially within obstetrics and gynecology several
papers on that topic describe promising results.
Gynecologic diagnostics relying on morphologic
signs and accurate distance and volume measurements
is one of the areas believed to benefit from 3D
ultrasound; however, until now only few prospective
works have been published, most of them counted as
preliminary. One of the main reasons might be the
huge technologic challenge. It is proposed that technologic
progress over the next few years will allow
feasible real-time 3D scanning. Gynecologic ultrasound
scanning will thereby undoubtedly take another
giant leap forward.
Why do we need 3D ultrasound in gynecology?
Great strides have been made in gynecology secondary
to the development of high-performance transvaginal
ultrasound (TVS) instruments; however, even
this advanced technology can provide only two-dimensional
(2D) views of three-dimensional (3D)
structures. Although an experienced examiner can
easily piece together sequential 2D planes for creating
a mental 3D image, individual sectional planes cannot
be achieved in a 2D image because of various difficulties.
Presently, 3D TVS can portray not only individual
image planes, it can also store complex tissue
volumes which can be digitally manipulated to display
a multiplanar view, allowing a systematic tomographic
survey of any particular field of interest. The
same technology can also display surface rendering
and transparency views to provide a more realistic
3D portrayal of various structures and anomalies.
Technique
Since the end of the 1980s, 3D ultrasound has become
a major field of research in gynecology. The
technique of acquiring 3D data involves making a set
of consecutive 2D ultrasound slices by moving the
transducer and continuously storing the images.
These ultrasound data must be converted into a regular
cubic representation before presentation in different
3D visualization modes. The creation of new ultrasound
sections from the 3D block, and also the
surface shading of a structure of interest, promise improvement
in the diagnosis of congenital uterine
anomalies and pelvic masses. In addition, the possibility
of volume calculation by 3D ultrasound has to
be considered as a clear innovation. At present, almost
all of the diagnoses illustrated by 3D ultrasound
can be made by 2D ultrasound, and this will continue
to be so in the foreseeable future. Recently, computerassisted
treatment of sonographic images has permitted
3D reconstruction in gynecology. This is
achieved by scanning a given volume containing the
organ of interest. Two practical options exist. Some
ultrasound probes are equipped with an automatic
scanning device while others use manual scanning,
electronically normalized or not. Both approaches
make use of an electronic matrix, i.e., a pile of 2D sonographic
images. Secondary cuts are possible
through the electronic matrix, including plans not
normally accessible to ultrasound scanning because
of anatomical limitations. One of the secondary cuts
most clinically useful is the frontal plane of the
uterus. This enables one to visualize the organ lying
flat as it is commonly drawn on medical sketches.
Studying the frontal plane of the uterus acquired
electronically from a 3D matrix improves the visualization
of possible interactions between structures
such as uterine fibroids and the endometrium. The