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Temporal and spectral imaging with micro-CT.

Publication ,  Journal Article
Johnston, SM; Johnson, GA; Badea, CT
Published in: Med Phys
August 2012

PURPOSE: Micro-CT is widely used for small animal imaging in preclinical studies of cardiopulmonary disease, but further development is needed to improve spatial resolution, temporal resolution, and material contrast. We present a technique for visualizing the changing distribution of iodine in the cardiac cycle with dual source micro-CT. METHODS: The approach entails a retrospectively gated dual energy scan with optimized filters and voltages, and a series of computational operations to reconstruct the data. Projection interpolation and five-dimensional bilateral filtration (three spatial dimensions + time + energy) are used to reduce noise and artifacts associated with retrospective gating. We reconstruct separate volumes corresponding to different cardiac phases and apply a linear transformation to decompose these volumes into components representing concentrations of water and iodine. Since the resulting material images are still compromised by noise, we improve their quality in an iterative process that minimizes the discrepancy between the original acquired projections and the projections predicted by the reconstructed volumes. The values in the voxels of each of the reconstructed volumes represent the coefficients of linear combinations of basis functions over time and energy. We have implemented the reconstruction algorithm on a graphics processing unit (GPU) with CUDA. We tested the utility of the technique in simulations and applied the technique in an in vivo scan of a C57BL∕6 mouse injected with blood pool contrast agent at a dose of 0.01 ml∕g body weight. Postreconstruction, at each cardiac phase in the iodine images, we segmented the left ventricle and computed its volume. Using the maximum and minimum volumes in the left ventricle, we calculated the stroke volume, the ejection fraction, and the cardiac output. RESULTS: Our proposed method produces five-dimensional volumetric images that distinguish different materials at different points in time, and can be used to segment regions containing iodinated blood and compute measures of cardiac function. CONCLUSIONS: We believe this combined spectral and temporal imaging technique will be useful for future studies of cardiopulmonary disease in small animals.

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Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

August 2012

Volume

39

Issue

8

Start / End Page

4943 / 4958

Location

United States

Related Subject Headings

  • X-Ray Microtomography
  • Water
  • Time Factors
  • Retrospective Studies
  • Reproducibility of Results
  • Radiographic Image Interpretation, Computer-Assisted
  • Nuclear Medicine & Medical Imaging
  • Normal Distribution
  • Models, Statistical
  • Mice, Inbred C57BL
 

Citation

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Johnston, S. M., Johnson, G. A., & Badea, C. T. (2012). Temporal and spectral imaging with micro-CT. Med Phys, 39(8), 4943–4958. https://doi.org/10.1118/1.4736809
Johnston, Samuel M., G Allan Johnson, and Cristian T. Badea. “Temporal and spectral imaging with micro-CT.Med Phys 39, no. 8 (August 2012): 4943–58. https://doi.org/10.1118/1.4736809.
Johnston SM, Johnson GA, Badea CT. Temporal and spectral imaging with micro-CT. Med Phys. 2012 Aug;39(8):4943–58.
Johnston, Samuel M., et al. “Temporal and spectral imaging with micro-CT.Med Phys, vol. 39, no. 8, Aug. 2012, pp. 4943–58. Pubmed, doi:10.1118/1.4736809.
Johnston SM, Johnson GA, Badea CT. Temporal and spectral imaging with micro-CT. Med Phys. 2012 Aug;39(8):4943–4958.

Published In

Med Phys

DOI

ISSN

0094-2405

Publication Date

August 2012

Volume

39

Issue

8

Start / End Page

4943 / 4958

Location

United States

Related Subject Headings

  • X-Ray Microtomography
  • Water
  • Time Factors
  • Retrospective Studies
  • Reproducibility of Results
  • Radiographic Image Interpretation, Computer-Assisted
  • Nuclear Medicine & Medical Imaging
  • Normal Distribution
  • Models, Statistical
  • Mice, Inbred C57BL