Nanoparticle\nContrast Agents for Dark-Field X‑ray\nImaging

The poor soft tissue contrast of X-ray CT necessitates\ncontrast\nagent use to improve diagnosis across disease applications, yet their\npoor detection sensitivity requires high injected doses, which restrict\nuse in at-risk populations. Dark-field X-ray imaging is emerging as\na more sensitive alternative to traditional attenuation-based imaging,\nleveraging scattered radiation to produce contrast. Yet aside from\nlarge, short-lived microbubbles, the alternate physics of dark-field\ndetection has yet to be exploited for contrast agent development.\nHere we demonstrate that high-Z nanoparticles can provide a new means\nto producing dark-field image contrast, promoting scatter via a higher\nrather than lower electron density compared to microbubbles, increasing\ndetection sensitivity compared to attenuation-based detection of a\nclinical iodine-based agent at an equivalent X-ray dose. As the use\nof dark-field X-ray imaging expands into more common clinical usage,\nthis will support the development of a new class of nanoparticulate\ncontrast agents.