Live 3D Echocardiography: A Replacement for Traditional 2D Echocardiography?
Robin C. Houck1,2,
Jason E. Cooke1,3 and
Edward A. Gill1
1 Department of Medicine, Division of Cardiology, University of Washington
School of Medicine, Harborview Medical Center, Box 359748, 329 Ninth Ave.,
Seattle, WA 98104-2599.
2 Present address: Medicine Department, University of Vermont, Burlington,
VT.
3 Present address: Medtronic, Inc., Minneapolis, MN.
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Fig. 1 —Diagram shows relationship of transesophageal
echocardiography probe to heart in example of use of rotational sweep to
acquire 2D images for a 3D data set. (Courtesy of Philips Medical Systems
[Andover, MA and Bothell, WA] and TomTec Imaging Systems GmbH [Munich,
Germany])
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Fig. 2 —Mechanical arm, first described by Dekker et al.
[1] in 1974, is shown.
Transducer (arrow) is held on mechanical arm. Location of transducer
is known because it is attached to mechanical arm.
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Fig. 3 —Photograph shows device attached to transducer that emitted
sound. See Past Techniques section for further discussion.
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Fig. 4 —Diagram illustrates freehand technique. Transducer is tracked
via a magnetic field created by magnet enclosed within cube. See Past
Techniques section for further discussion. (Courtesy of TomTec Imaging Systems
GmbH, Munich, Germany)
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Fig. 5 —Rotational device designed to hold a transducer is shown.
Transducer, an older mechanical type, is shown protruding from bottom of
rotator (arrow). (Courtesy of TomTec Imaging Systems GmbH, Munich,
Germany)
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Fig. 6A —Techniques used for 3D image acquisition protocols. Diagrams
show fanning (A) and linear or stepper (B) motor devices used
for transthoracic 3D image acquisition protocol. Fanning device follows fan
motion, and linear device, by definition, follows linear tracking protocol.
(Courtesy of TomTec Imaging Systems GmbH, Munich, Germany)
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Fig. 6B —Techniques used for 3D image acquisition protocols. Diagrams
show fanning (A) and linear or stepper (B) motor devices used
for transthoracic 3D image acquisition protocol. Fanning device follows fan
motion, and linear device, by definition, follows linear tracking protocol.
(Courtesy of TomTec Imaging Systems GmbH, Munich, Germany)
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Fig. 7 —Photograph shows transducer designed with rotation
capabilities contained within housing. End result is similar to
Figure 5, but rather than
having a separate device to hold transducer, transducer itself has electronic
steering that steers in rotational pattern. Design is also similar to
transesophageal echocardiography transducer shown in
Figure 1. (Courtesy of Philips
Medical Systems, Andover, MA and Bothell, WA)
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Fig. 8A —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Three-dimensional image
of stenotic mitral valve (arrows, A) from left ventricular
side of valve (A) and corresponding 2D cut (B) are shown.
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Fig. 8B —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Three-dimensional image
of stenotic mitral valve (arrows, A) from left ventricular
side of valve (A) and corresponding 2D cut (B) are shown.
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Fig. 8C —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Atrial septal
defect—ASD in C and arrow in D—is shown on 3D image
(C) in its entirety as opposed to corresponding 2D cut (D). In
C, AoV refers to aortic valve.
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Fig. 8D —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Atrial septal
defect—ASD in C and arrow in D—is shown on 3D image
(C) in its entirety as opposed to corresponding 2D cut (D). In
C, AoV refers to aortic valve.
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Fig. 8E —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Three-dimensional image
shows aortic valve (arrow) with focal sclerosis of commissure between
the non and right coronary cusp.
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Fig. 8F —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Two-dimensional image
shows flail posterior mitral valve leaflet (arrow).
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Fig. 8G —Three-dimensional images obtained using rotational
transesophageal echocardiography acquisition and subsequent reconstruction.
All are designed to show benefits of en face view of entire structure with
depth as opposed to 2D image showing only single cut. Three-dimensional image
of mitral valve in systole shows middle scallop of posterior leaflet.
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Fig. 9 —Diagram illustrates real-time 3D transthoracic
echocardiography probe with sparse array design. Note comparison with dense
array shown in Figures 11A and
11B. See First-Rendition of
Real-Time 3D Imaging section for discussion. (Courtesy of Philips Medical
Systems, Andover, MA and Bothell, WA)
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Fig. 10 —Standard 2D echocardiography images of left ventricle
(right) and corresponding cross-sectional views (left), or C
scans. Four-chamber (top) and two-chamber (bottom) views are
shown. This figure is from older version of real-time 3D imaging. (Courtesy of
D. Adams, Durham, NC)
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Fig. 11A —Images show schematic and photograph of dense array real-time
3D transducer. (Courtesy of Philips Medical Systems, Andover, MA and Bothell,
WA) Schematic representation of dense array real-time 3D transducer. Each
square represents an element. See First-Rendition of Real-Time 3D Imaging
section for discussion.
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Fig. 11B —Images show schematic and photograph of dense array real-time
3D transducer. (Courtesy of Philips Medical Systems, Andover, MA and Bothell,
WA) Photograph shows live 3D matrix transducer (Matrix X4) manufactured by
Philips Medical Systems.
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Fig. 12 —Diagram depicts transition from one-dimensional (1D) to 3D
data set. Note single scan line from single crystal 1D or A-mode scan
transitioning to axial and lateral imaging with 2D phased-array scanning and
to axial, lateral, and elevation scanning with 3D matrix scanning. See further
discussion in Live 3D Imaging section. C scan is essentially an axial cut
through 3D data set. (Illustration by Richard Gersony)
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Fig. 13 —Progression from 2D imaging to 3D narrow-angle (NA) to 3D
full-volume (FV) imaging is shown with respective representative images. In 2D
imaging, only single slice of data is acquired with result being 2D image with
no depth. In 3D narrow-angle imaging, entire heart volume is not obtained;
rather, 3D slice of varying width, depending on resolution, is obtained and
simultaneous volume rendering adds depth not seen with 2D slice. Finally, for
3D full-volume imaging, example shows that although entire volume of heart is
captured, exact same volume-rendered slice shown in 3D narrow-angle imaging
can be extracted from larger volume data set resulting in identical image.
(Illustration by Richard Gersony)
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Fig. 14A —Diagrams show concept of full-volume versus narrow-angle
imaging compared with 2D imaging. Note lack of elevation steering for 2D
imaging and that larger volume data set is acquired for full-volume imaging.
(Illustration by Richard Gersony)
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Fig. 14B —Diagrams show concept of full-volume versus narrow-angle
imaging compared with 2D imaging. Concept of acquisition of full volume is
shown. Full volume is acquired from total of four cardiac cycles. Each
individual cardiac cycle contributes one fourth of thickness of entire data
set as illustrated with individual colors. Cardiac gating is required to meld
four cardiac cycles into one. (Illustration by Richard Gersony)
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Fig. 14C —Diagrams show concept of full-volume versus narrow-angle
imaging compared with 2D imaging. When more than one cardiac cycle is used, it
becomes important to match individual frames within a cardiac cycle. As
illustrated, when one cardiac cycle is acquired, each cardiac cycle is divided
into multiple frames; total of 11 frames are shown in this example. Number of
frames used for each acquisition depends on heart rate (R-R interval) as well
as frame rate of acquisition machine. It is desirable (but not always
possible) to have same R-R interval for each cardiac cycle so that each frame
can be matched. (Courtesy of TomTec Imaging Systems GmbH, Munich, Germany)
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Fig. 15 —Narrow-angle versus full-volume imaging is shown as well as
different levels of resolution possible (high, medium, low). In this
particular algorithm for 3D imaging, choice was made to keep number of scan
lines; hence, volume rate is constant and results in change in resolution from
narrow angle to full volume. See Full-Volume Versus Narrow-Angle Acquisition
section for further discussion regarding resolution and zoom. (Illustration by
Richard Gersony)
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Fig. 16 —Versatility of 3D data set is shown with three consecutive
cropping planes (lateral, elevation, and azimuthal [axial]), each
perpendicular to other, used to create 3D images that are perpendicular to one
another. Three-dimensional rendering can be performed in any direction
perpendicular to reference plane. Note that final image (drawing E) represents
equivalent of C scan with cutting plane being perpendicular to axial plane or
depth of ultrasound beam. (Illustration by Richard Gersony)
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Fig. 17A —Graphs show correlation and degree of agreement between 2D
echocardiography and 3D echocardiography compared with currently perceived
gold standard of cardiac MRI. Note considerable improvement in both
correlation and agreement to MRI provided by live 3D imaging compared with 2D
imaging. (Reprinted with permission from Circulation
[47]). Graphs show correlation
and degree of agreement between 2D echocardiography and live 3D
echocardiography (A) and between each echocardiography technique and
cardiac MRI (B) for determining left ventricular (LV) mass.
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Fig. 17B —Graphs show correlation and degree of agreement between 2D
echocardiography and 3D echocardiography compared with currently perceived
gold standard of cardiac MRI. Note considerable improvement in both
correlation and agreement to MRI provided by live 3D imaging compared with 2D
imaging. (Reprinted with permission from Circulation
[47]). Graphs show correlation
and degree of agreement between 2D echocardiography and live 3D
echocardiography (A) and between each echocardiography technique and
cardiac MRI (B) for determining left ventricular (LV) mass.
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Fig. 18A —Live 3D imaging examples of how 3D imaging is better than 2D
imaging for evaluating structures such as septal defects. Atrial septal defect
(ASD) occluder device (Amplatz Occluder Device, AGA Medical Corporation) is
shown on 3D imaging. Note ability to see device en face in B after
tilting image shown in A. In B, AoV indicates aortic valve.
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Fig. 18B —Live 3D imaging examples of how 3D imaging is better than 2D
imaging for evaluating structures such as septal defects. Atrial septal defect
(ASD) occluder device (Amplatz Occluder Device, AGA Medical Corporation) is
shown on 3D imaging. Note ability to see device en face in B after
tilting image shown in A. In B, AoV indicates aortic valve.
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Fig. 19A —Live 3D transthoracic view of mitral valve repair. Images
show annuloplasty ring from parasternal long view (A) and apical view
(B). Arrows point to left atrium (LA, A).
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Fig. 19B —Live 3D transthoracic view of mitral valve repair. Images
show annuloplasty ring from parasternal long view (A) and apical view
(B). Arrows point to left atrium (LA, A).
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Fig. 19C —Live 3D transthoracic view of mitral valve repair. Images
show mitral valve and annuloplasty ring with view from left atrial side of
valve during systole (C) and diastole (D). These images were
obtained via reconstructive transesophageal echocardiography technology.
Arrows depict central orifice (thick arrow) and incoming pulmonary
veins (thin arrow) on periphery.
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Fig. 19D —Live 3D transthoracic view of mitral valve repair. Images
show mitral valve and annuloplasty ring with view from left atrial side of
valve during systole (C) and diastole (D). These images were
obtained via reconstructive transesophageal echocardiography technology.
Arrows depict central orifice (thick arrow) and incoming pulmonary
veins (thin arrow) on periphery.
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Copyright © 2006 by the American Roentgen Ray Society.
