Grating interferometry mammography (GIM) is an experimental breast imaging method at the edge of being clinically implemented. Besides attenuation, GIM can measure the refraction and scattering of x-rays resulting in differential phase contrast (DPC) and dark-field (DF) images. In this exploratory study, we assessed the feasibility of using microbubbles as a contrast agent in GIM. Two millilitres of microbubbles and iodine were respectively injected into ex vivo breast phantoms, consisting of fresh chicken breasts. Native and postcontrast images were acquired with a clinically compatible GIM setup, operated at 38 kVp, 14-s acquisition time, and with a dose of 1.3 mGy. The visibility of the contrast agents was analysed in a side-by-side comparison by three radiologists. The contrast-to-noise-ratio (CNR) was calculated for each contrast agent. We found that both contrast agents were judged to be visible by the readers. The mean CNR was 3.1 ± 1.9 for microbubbles in DF and 24.2 ± 6.5 for iodine in attenuation. In conclusion, this is a first proof-of-mechanism study that microbubbles could be used as a contrast agent in clinically compatible GIM, due to their scattering properties, which implies the potential use of a contrast agent with a high safety profile in x-ray-based breast imaging.

中文翻译：

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微气泡作为光栅干涉钼靶检查中的造影剂：离体机理研究。

光栅干涉乳腺摄影（GIM）是一种在临床上尚处于边缘的实验性乳房成像方法。除了衰减之外，GIM还可以测量x射线的折射和散射，从而产生差分相衬（DPC）和暗场（DF）图像。在这项探索性研究中，我们评估了在GIM中使用微泡作为造影剂的可行性。将两毫升微泡和碘分别注入离体体内乳房幻像，由新鲜的鸡胸肉组成。原始和对比度图像是通过临床兼容的GIM设置采集的，以38 kVp的速度运行，采集时间为14秒，剂量为1.3 mGy。三名放射科医生在并排比较中分析了造影剂的可见性。计算每种造影剂的对比噪声比（CNR）。我们发现，两种造影剂均被读者视为可见。DF中微气泡的平均CNR为3.1±1.9，碘衰减的平均CNR为24.2±6.5。总而言之，这是第一个机理证明研究，因为微泡具有散射特性，因此可以在临床上兼容的GIM中用作造影剂，这意味着潜在地使用具有高安全性的造影剂在x-基于射线的乳房成像。