Microbubbles as a scattering contrast agent for grating-based x-ray dark-field imaging.
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.
Department of Physics and Institute of Medical Engineering, Technische Universität München, James-Franck-Straße, D-85748 Garching, Germany. astrid.velroyen@tum.de
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Velroyen
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Bech
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Malecki
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Tapfer
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Yaroshenko
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Ingrisch
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Cyran
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Auweter
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Nikolaou
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Reiser
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Pfeiffer
D000042:Absorption; D003198:Computer Simulation; D003287:Contrast Media / Q000494:pharmacology*; D003952:Diagnostic Imaging / Q000379:methods*; D004867:Equipment Design; D006801:Humans; D007368:Interferometry / Q000379:methods; D007674:Kidney Diseases / Q000473:pathology; D045423:Microbubbles; D012542:Scattering, Radiation; D014463:Ultrasonography / Q000379:methods; D014965:X-Rays
D003287:Contrast Media