| 1. |
- Yaroshenko, A., et al.
(author)
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Preclinical x-ray dark-field radiography for pulmonary emphysema evaluation
- 2013
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In: ISBI 2013 - 2013 IEEE 10th International Symposium on Biomedical Imaging : From Nano to Macro - From Nano to Macro. - 1945-7928 .- 1945-8452. - 9781467364553 - 9781467364560 ; , s. 370-373
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Conference paper (peer-reviewed)abstract
- Pulmonary emphysema is a widespread disorder characterized by irreversible destruction of alveolar walls. The spatial distribution of the disease, so far, could only be obtained using an x-ray CT scan, implying a high patient dose. X-ray scattering on alveolar structures is measured in the dark-field signal. The signal is dependent on the size of alveoli and therefore, a combination of absorption and dark-field signal is explored for mapping the distribution of emphysema in the lung on x-ray projection images. In this study three excised murine lungs with pulmonary emphysema and three control samples were imaged using a compact, cone-beam, small-animal x-ray dark-field scanner with a polychromatic source. Statistical analysis of the results, based on a combination of transmission and dark-field signals, revealed a distinct difference between emphysematous and control samples. Subsequently, the distribution of emphysema was mapped out per-pixel for the lungs and showed good agreement with histological findings.
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| 2. |
- Velroyen, A, et al.
(author)
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Grating-based X-ray Dark-field Computed Tomography of Living Mice.
- 2015
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In: EBioMedicine. - : Elsevier BV. - 2352-3964. ; 2:10, s. 1500-1506
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Journal article (peer-reviewed)abstract
- Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT). The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT), based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural - and thus indirectly functional - changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU) scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue.
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| 3. |
- Velroyen, A., et al.
(author)
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Microbubbles as a scattering contrast agent for grating-based x-ray dark-field imaging
- 2013
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In: Physics in Medicine and Biology. - 1361-6560. ; 58:4, s. 37-46
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Journal article (peer-reviewed)abstract
- In clinically established-absorption-based-biomedical x-ray imaging, contrast agents with high atomic numbers (e.g. iodine) are commonly used for contrast enhancement. The development of novel x-ray contrast modalities such as phase contrast and dark-field contrast opens up the possible use of alternative contrast media in x-ray imaging. We investigate using ultrasound contrast agents, which unlike iodine-based contrast agents can also be administered to patients with renal impairment and thyroid dysfunction, for application with a recently developed novel x-ray dark-field imaging modality. To produce contrast from these microbubble-based contrast agents, our method exploits ultra-small-angle coherent x-ray scattering. Such scattering dark-field x-ray images can be obtained with a grating-based x-ray imaging setup, together with refraction-based differential phase-contrast and the conventional attenuation contrast images. In this work we specifically show that ultrasound contrast agents based on microbubbles can be used to produce strongly enhanced dark-field contrast, with superior contrast-to-noise ratio compared to the attenuation signal. We also demonstrate that this method works well with an x-ray tube-based setup and that the relative contrast gain even increases when the pixel size is increased from tenths of microns to clinically compatible detector resolutions about up to a millimetre.
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