Three-dimensional spine reconstruction methods currently used to study scoliosis require manual identification of several anatomical features, which is time-consuming, costly and error-prone

Daniel C. Moura

Hubert Labelle

Jonathan Boisvert

Jorge G. Barbosa

João Manuel R. S. Tavares

Repositório Aberto da Universidade do Porto

Fast 3D Reconstruction of the Spine by Non-expert Users Using a Statistical Articulated Model Daniel C. MOURA a,b; Jonathan BOISVERT e,f; Jorge G. BARBOSA a,b;João Manuel R. S. TAVARES c,d; Hubert LABELLE ga Laboratório de Inteligência Artificial e de Ciência de Computadores, Porto, Portugal b Universidade do Porto, Faculdade de Engenharia, Dep. Eng. Informática, Porto, Portugal c Instituto de Engenharia Mecânica e Gestão Industrial, Porto, Portugal d Universidade do Porto, Faculdade de Engenharia, Dep. de Eng. Mecânica, Porto, Portugal e National Research Council Canada, Ottawa, Ontario, Canada f École Polytechnique de Montréal, Montréal, Quebec, Canada g Sainte-Justine Hospital Research Centre, Montréal, Quebec, Canada Introduction: Three-dimensional spine reconstruction methods currently used to study scoliosis require manual identification of several anatomical features, which is time-consuming, costly and error-prone. Objectives: To provide fast 3D reconstructions of the spine that may be accomplished by non-expert users. More specifically, recovering the 3D position of 6 anatomical landmarks per vertebra based on a pair of radiographs with minimal user interaction.Materials and Methods: Splines approximating the spine midline were identified by end-users using a small number of control points (typically 4 to 7 points on each radiograph). Then, vertebrae location, rotation and 3D anatomical landmarks were recovered by deforming a statistical articulated model that captures inter-vertebrae variability (compiled using 291 prior reconstructions). The deformation optimizes both the fit with the user’s splines and the prior probability given by the statistical model. A set of 14 in vivo exams of scoliotic patients were used for validating the method. 3D reconstructions obtained using a previously validated method were compared with reconstructions using the proposed method performed by 2 volunteers with limited knowledge on spine radiology. Volunteers only had 20 minutes of training with the software tool (figure 1).   Results: The mean reconstruction errors were 3.4mm for the endplates and 4.8mm for the pedicles. Furthermore, the average reconstruction time was 1min28s. Conclusion and Significance: Results show that rough reconstructions of the spine may be rapidly achieved by non-expert users with very little training. This makes the method attractive when fast reconstructions are required, or when dedicated personnel would be too expensive.Research into Spinal Deformities 7C.-E. Aubin et al. (Eds.)IOS Press, 2010© 2010 The authors and IOS Press. All rights reserved.doi:10.3233/978-1-60750-573-0-268268D.C. Moura et al. / Fast 3D Reconstruction of the Spine by Non-Expert Users 269

Fast 3D reconstruction of the spine by non-expert users using a statistical articulated model

Open Repository of the University of Porto

Fast 3D Reconstruction of the Spine by 
Non-expert Users Using a Statistical 
Articulated Model 
Daniel C. MOURA a,b; Jonathan BOISVERT e,f; Jorge G. BARBOSA a,b;
João Manuel R. S. TAVARES c,d; Hubert LABELLE g
a Laboratório de Inteligência Artificial e de Ciência de Computadores, Porto, Portugal 
b Universidade do Porto, Faculdade de Engenharia, Dep. Eng. Informática, Porto, 
Portugal 
c Instituto de Engenharia Mecânica e Gestão Industrial, Porto, Portugal 
d Universidade do Porto, Faculdade de Engenharia, Dep. de Eng. Mecânica, Porto, 
Portugal 
e National Research Council Canada, Ottawa, Ontario, Canada 
f École Polytechnique de Montréal, Montréal, Quebec, Canada 
g Sainte-Justine Hospital Research Centre, Montréal, Quebec, Canada 
Introduction: Three-dimensional spine reconstruction methods currently used to 
study scoliosis require manual identification of several anatomical features, which 
is time-consuming, costly and error-prone. 
Objectives: To provide fast 3D reconstructions of the spine that may be 
accomplished by non-expert users. More specifically, recovering the 3D position 
of 6 anatomical landmarks per vertebra based on a pair of radiographs with 
minimal user interaction.
Materials and Methods: Splines approximating the spine midline were identified 
by end-users using a small number of control points (typically 4 to 7 points on 
each radiograph). Then, vertebrae location, rotation and 3D anatomical landmarks 
were recovered by deforming a statistical articulated model that captures inter-
vertebrae variability (compiled using 291 prior reconstructions). The deformation 
optimizes both the fit with the user’s splines and the prior probability given by the 
statistical model. 
A set of 14 in vivo exams of scoliotic patients were used for validating the method. 
3D reconstructions obtained using a previously validated method were compared 
with reconstructions using the proposed method performed by 2 volunteers with 
limited knowledge on spine radiology. Volunteers only had 20 minutes of training 
with the software tool (figure 1).   
Results: The mean reconstruction errors were 3.4mm for the endplates and 4.8mm 
for the pedicles. Furthermore, the average reconstruction time was 1min28s. 
Conclusion and Significance: Results show that rough reconstructions of the 
spine may be rapidly achieved by non-expert users with very little training. This 
makes the method attractive when fast reconstructions are required, or when 
dedicated personnel would be too expensive.
Research into Spinal Deformities 7
C.-E. Aubin et al. (Eds.)
IOS Press, 2010
© 2010 The authors and IOS Press. All rights reserved.
doi:10.3233/978-1-60750-573-0-268
268
D.C. Moura et al. / Fast 3D Reconstruction of the Spine by Non-Expert Users 269


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https://repositorio-aberto.up.pt/bitstream/10216/24375/2/61364.pdf

Fast 3D reconstruction of the spine by non-expert users using a statistical articulated model

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