Optimization of Image Quality in Retrospective Respiratory-Gated Micro-CT for Quantitative Measurements of Lung Function in Free-Breathing Rats

Nancy L. Ford, Andrew Jeklin, Karen Yip, Darren Yohan, David W. Holdsworth, Maria Drangova

Department of Oral Biological and Medical Sciences, The University of British Columbia, Vancouver, Canada.
Department of Physics, Ryerson University, Toronto, Canada.
Schulich School of Medicine & Dentistry, The University of Western Ontario, London, Canada.

DOI: 10.4236/jbise.2014.74020                

Abstract

Objective: To optimize scan time and X-ray dose with no loss of image quality for retrospectively gated micro-CT scans of free-breathing rats. Methods: Five free-breathing rats were scanned using a dynamic micro-CT scanner over 10 continuous gantry rotations (50 seconds and entrance dose of 0.28 Gy). The in-phase projection views were selected and reconstructed, representing peak inspiration and end expiration from all 10 rotations and progressively fewer rotations. A least error method was also used to ensure that all angular positions were filled. Image quality and reproducibility for physiological measurements were compared for the two techniques. Results: The least error approach underestimated the lung volume, air content in the lung at peak inspiration, and tidal volume. Other measurements showed no differences between the projection-sorting techniques. Conclusions: Seven gantry rotations (35 seconds and 0.2 Gy dose) proved to be the optimal protocol for both the in-phase images and the least error images.

Keywords

Respiratory-Gating; Micro-CT; Lung Imaging; Free-Breathing Rats; Tidal Volume

Conflicts of Interest

The authors declare no conflicts of interest.

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