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Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging.

Publication ,  Journal Article
Kim, E; Bowsher, J; Thomas, AS; Sakhalkar, H; Dewhirst, M; Oldham, M
Published in: Phys Med Biol
October 7, 2008

Optical computed tomography (optical-CT) and optical-emission computed tomography (optical-ECT) are new techniques for imaging the 3D structure and function (including gene expression) of whole unsectioned tissue samples. This work presents a method of improving the quantitative accuracy of optical-ECT by correcting for the 'self'-attenuation of photons emitted within the sample. The correction is analogous to a method commonly applied in single-photon-emission computed tomography reconstruction. The performance of the correction method was investigated by application to a transparent cylindrical gelatin phantom, containing a known distribution of attenuation (a central ink-doped gelatine core) and a known distribution of fluorescing fibres. Attenuation corrected and uncorrected optical-ECT images were reconstructed on the phantom to enable an evaluation of the effectiveness of the correction. Significant attenuation artefacts were observed in the uncorrected images where the central fibre appeared approximately 24% less intense due to greater attenuation from the surrounding ink-doped gelatin. This artefact was almost completely removed in the attenuation-corrected image, where the central fibre was within approximately 4% of the others. The successful phantom test enabled application of attenuation correction to optical-ECT images of an unsectioned human breast xenograft tumour grown subcutaneously on the hind leg of a nude mouse. This tumour cell line had been genetically labelled (pre-implantation) with fluorescent reporter genes such that all viable tumour cells expressed constitutive red fluorescent protein and hypoxia-inducible factor 1 transcription-produced green fluorescent protein. In addition to the fluorescent reporter labelling of gene expression, the tumour microvasculature was labelled by a light-absorbing vasculature contrast agent delivered in vivo by tail-vein injection. Optical-CT transmission images yielded high-resolution 3D images of the absorbing contrast agent, and revealed highly inhomogeneous vasculature perfusion within the tumour. Optical-ECT emission images yielded high-resolution 3D images of the fluorescent protein distribution in the tumour. Attenuation-uncorrected optical-ECT images showed clear loss of signal in regions of high attenuation, including regions of high perfusion, where attenuation is increased by increased vascular ink stain. Application of attenuation correction showed significant changes in an apparent expression of fluorescent proteins, confirming the importance of the attenuation correction. In conclusion, this work presents the first development and application of an attenuation correction for optical-ECT imaging. The results suggest that successful attenuation correction for optical-ECT is feasible and is essential for quantitatively accurate optical-ECT imaging.

Duke Scholars

Published In

Phys Med Biol

DOI

ISSN

0031-9155

Publication Date

October 7, 2008

Volume

53

Issue

19

Start / End Page

5371 / 5383

Location

England

Related Subject Headings

  • Transplantation, Heterologous
  • Tomography, Optical
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Probability
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Neoplasms
  • Image Enhancement
  • Hypoxia-Inducible Factor 1
 

Citation

APA
Chicago
ICMJE
MLA
NLM
Kim, E., Bowsher, J., Thomas, A. S., Sakhalkar, H., Dewhirst, M., & Oldham, M. (2008). Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging. Phys Med Biol, 53(19), 5371–5383. https://doi.org/10.1088/0031-9155/53/19/007
Kim, E., J. Bowsher, A. S. Thomas, H. Sakhalkar, M. Dewhirst, and M. Oldham. “Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging.Phys Med Biol 53, no. 19 (October 7, 2008): 5371–83. https://doi.org/10.1088/0031-9155/53/19/007.
Kim E, Bowsher J, Thomas AS, Sakhalkar H, Dewhirst M, Oldham M. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging. Phys Med Biol. 2008 Oct 7;53(19):5371–83.
Kim, E., et al. “Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging.Phys Med Biol, vol. 53, no. 19, Oct. 2008, pp. 5371–83. Pubmed, doi:10.1088/0031-9155/53/19/007.
Kim E, Bowsher J, Thomas AS, Sakhalkar H, Dewhirst M, Oldham M. Improving the quantitative accuracy of optical-emission computed tomography by incorporating an attenuation correction: application to HIF1 imaging. Phys Med Biol. 2008 Oct 7;53(19):5371–5383.
Journal cover image

Published In

Phys Med Biol

DOI

ISSN

0031-9155

Publication Date

October 7, 2008

Volume

53

Issue

19

Start / End Page

5371 / 5383

Location

England

Related Subject Headings

  • Transplantation, Heterologous
  • Tomography, Optical
  • Sensitivity and Specificity
  • Reproducibility of Results
  • Probability
  • Phantoms, Imaging
  • Nuclear Medicine & Medical Imaging
  • Neoplasms
  • Image Enhancement
  • Hypoxia-Inducible Factor 1