Stereolithographic biomodeling to create tangible hard copies of cardiac structures from echocardiographic data
In vitro and in vivo validation
Thomas M. Binder, MD*,
Deddo Moertl, MD*,
Gerald Mundigler, MD*,
Gerhard Rehak*,
Manfred Franke*,
Georg Delle-Karth, MD*,
Werner Mohl, MD ,
Helmut Baumgartner, MD, FACC* and
Gerald Maurer, MD, FACC*
* Department of Cardiology, University of Vienna, AKH, Vienna, Austria
Department of Cardiovascular Surgery, University of Vienna, AKH, Vienna, Austria
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Figure 1 Image processing procedure: A rotational TEE scan is performed to acquire a volumetric data set. The images are transferred to a 3D workstation for postprocessing to reconstruct paraplane images. Image segmentation is performed off-line. The segmented images are then exported to the stereolithograph where they serve as a digital 3D pattern to create physical models.
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Figure 2 Stereolithograph: The stereolithographic equipment (right) consists of a computer workstation (A, controller), a laser with an optical system (B) and a processing chamber (C). The processing chamber (left) is filled with a liquid monomer. A laser beam (D) selectively polymerizes ultraviolet sensitive liquid resin (E) on a platform suspended in a vat of the liquid. The laser is steered to corresponding positions on the surface of the liquid polymer according to the echocardiographic image (x, y axis). Successive layers (z axis) are added by lowering the platform on which the model is built to expose a new surface. Each layer fuses to the one below, allowing the creation of complex 3D structures (F).
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Figure 3 Regression analysis (A) and Bland Altman plot (B) comparing the volumes of balloon phantoms and liver specimens to their replicas. Regression analysis (C) and Bland-Altman plot (D) comparing the geometry (maximal height, width and length) of each of the liver phantoms to its corresponding model.
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Figure 4 Balloon phantom (left), its corresponding 3D reconstruction (center) and the actual photograph of the hard-copy model (right).
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Figure 5 Liver specimen (left) and its corresponding model (right).
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Figure 6 Normal MV: Stereolithographic model of a normal MV at systole as seen from the left atrium (A) and from the left ventricle (B). Even details of the MV are clearly visible. Back light photography of the model (C) demonstrates the transparent appearance of the acrylic material.
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Figure 7 Flail posterior leaflet: Flail leaflet (arrow) as seen during transesophageal echocardiography (A) intraoperative inspection of the valve (B) confirmed MV prolapse, chordal rupture and a flail posterior leaflet (medial scallop). The flail segment of the posterior leaflet can be appreciated in the 3D reconstruction (at systole) (C) and is also visible in the stereolithographic model (D).
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Figure 8 Mitral stenosis: Three-dimensional reconstructions and stereolithographic replicas of a MV with moderate to severe mitral stenosis (MVA = 1, 2 cm2) during diastole as seen both from the left atrium (top) and from the left ventricle (bottom). Note the close resemblance of the model to the 3D reconstruction. Even detailed morphologic features such as anterior MV doming or the size and geometry of the MV orifice can be appreciated.
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