Automatic segmentation propagation of the aorta in real-time phase contrast MRI using nonrigid registration

Authors

  • Freddy Odille PhD,

    1. Centre for Medical Image Computing, UCL Department of Medical Physics and Bioengineering, United Kingdom
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  • Jennifer A. Steeden MEng,

    1. Centre for Medical Image Computing, UCL Department of Medical Physics and Bioengineering, United Kingdom
    2. Centre for Cardiovascular MR, UCL Institute of Child Health, London, United Kingdom
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  • Vivek Muthurangu MD,

    1. Centre for Cardiovascular MR, UCL Institute of Child Health, London, United Kingdom
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  • David Atkinson PhD

    Corresponding author
    1. Centre for Medical Image Computing, UCL Department of Medical Physics and Bioengineering, United Kingdom
    • Dept. of Medical Physics and Bioengineering, University College London, London WC1E 6BT UK
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Abstract

Purpose

To assess the use of a nonrigid registration technique for semi-automatic segmentation of the aorta from real-time velocity mapping MRI.

Materials and Methods

Real-time phase contrast images were acquired to measure flow and stroke volumes in 10 subjects, during free breathing, at rest, and during exercise. A nonrigid registration algorithm was developed to propagate a manually drawn region of interest in the aorta from one frame to all other frames of the real-time sequence (148 images). Thus the technique provided a semi-automatic segmentation over the whole sequence of images. The accuracy was assessed by comparison with manual segmentations in terms of Dice overlap measures and stroke volumes (SV).

Results

Semi-automatic segmentations were comparable to manual ones (Dice score of 0.89 ± 0.04). Inter-observer reproducibility was similar for manual and semi-automatic segmentations (Dice score of 0.90 ± 0.04 in both cases, the difference was not significant). SV measurements also showed good agreement between manual and semi-automatic segmentations (correlation coefficient r > 0.94), and the differences were not statistically significant.

Conclusion

Although real-time phase contrast images have compromised image quality, a fast and robust segmentation of the aorta was possible using the registration-based technique. J. Magn. Reson. Imaging 2011;33:232–238. © 2010 Wiley-Liss, Inc.

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