Complementary use of x-ray dark-field and attenuation computed tomography in quantifying pulmonary fibrosis in a mouse model

Brandon J. Nelson; Shuai Leng; Thomas Koenig; Cynthia H. McCollough

doi:10.1117/12.2612877

4 April 2022 Complementary use of x-ray dark-field and attenuation computed tomography in quantifying pulmonary fibrosis in a mouse model

Brandon J. Nelson, Shuai Leng, Thomas Koenig, Cynthia H. McCollough

Author Affiliations +

Proceedings Volume 12036, Medical Imaging 2022: Biomedical Applications in Molecular, Structural, and Functional Imaging; 120360W (2022) https://doi.org/10.1117/12.2612877
Event: SPIE Medical Imaging, 2022, San Diego, California, United States

Abstract

X-ray dark-field measured on laboratory sources with large focal spots and detector apertures is sensitive to intra-pixel phase gradients abundant in the lungs due to its hierarchical structure of subdividing airways terminating in thin-walled alveoli. This work leverages this sensitivity to exploit complementary information from x-ray dark-field and attenuation computed tomography (CT) images to improve quantification of morphology in pulmonary fibrosis. Specifically, a darkfield enhanced attenuation technique is developed to restore edges and small features in the attenuation image lost to blurring by appropriately scaling and subtracting the dark-field image. An intratracheally treated bleomycin mouse model of pulmonary fibrosis was used to evaluate the impact of the proposed dark-field enhanced attenuation technique on quantifying fibrosis extent. The mouse model was fixated ex vivo to be imaged with a Talbot-Lau grating interferometer micro-CT to generate x-ray dark field and attenuation volumes of 60 µm voxels. Then the specimen was imaged with a reference micro-CT scanner at 5 μm voxel resolution to get a ground truth approximation of local structure. The volumes were co-registered for visual and pixelwise comparisons. Qualitative image comparisons were used to assess visual sharpness while Bland-Altman plots were used to assess agreement with the reference scan at quantifying fibrosis in terms of tissue area fraction measured in 80 randomly sampled nonoverlapping 2 mm square patches. Visual comparisons demonstrated enhanced sharpness and retention of small lung structures while BlandAltman analysis revealed an improved agreement ratio of 0.544 compared to 0.374 in the original attenuation image with a reduction in variance. These results demonstrate that dark-field and attenuation images can be used together to improve resolution of small structures and aid in quantification of pulmonary fibrosis in a mouse model.

Conference Presentation

Citation Download Citation

Brandon J. Nelson, Shuai Leng, Thomas Koenig, and Cynthia H. McCollough "Complementary use of x-ray dark-field and attenuation computed tomography in quantifying pulmonary fibrosis in a mouse model", Proc. SPIE 12036, Medical Imaging 2022: Biomedical Applications in Molecular, Structural, and Functional Imaging, 120360W (4 April 2022); https://doi.org/10.1117/12.2612877

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