超高场 (UHF) 磁共振成像 (MRI) 是生物医学成像的关键基石，但错误成像的挑战仍然存在，限制了其全部潜力。尽管双模式造影剂的发展改善了传统 MRI，但由于高磁矩，它们在 UHF 中的效果仍然不理想，导致 T1 弛豫度降低和 T2 弛豫度过度增强。在此，我们报告了一种由 DNA 介导的氧化铁纳米粒子的磁性二聚体组装 (DMA)，它利用 UHF 定制的纳米磁性来实现无故障的 UHF-MRI。 DMA 在 9 T 下表现出双重增强的纵向弛豫率 4.42 mM-1·s-1 和横向弛豫率 26.23 mM-1·s-1，展示了典型的 T1-T2 双模 UHF-MRI 造影剂。重要的是，DMA利用T1-T2双模态图像融合实现无伪影的乳腺癌可视化，以前所未有的精度有效过滤百微米级假阳性信号的干扰。 UHF 定制的 T1-T2 双模式 DMA 造影剂有望提高疾病诊断中 MR 成像的准确性。

Ultra-high-field (UHF) magnetic resonance imaging (MRI) stands as a pivotal cornerstone in biomedical imaging, yet the challenge of false imaging persists, constraining its full potential. Despite the development of dual-mode contrast agents improving conventional MRI, their effectiveness in UHF remains suboptimal due to the high magnetic moment, resulting in diminished T1 relaxivity and excessively enhanced T2 relaxivity. Herein, we report a DNA-mediated magnetic-dimer assembly (DMA) of iron oxide nanoparticles that harnesses UHF-tailored nanomagnetism for fault-free UHF-MRI. DMA exhibits a dually enhanced longitudinal relaxivity of 4.42 mM-1·s-1 and transverse relaxivity of 26.23 mM-1·s-1 at 9 T, demonstrating a typical T1-T2 dual-mode UHF-MRI contrast agent. Importantly, DMA leverages T1-T2 dual-modality image fusion to achieve artifact-free breast cancer visualization, effectively filtering interference from hundred-micrometer-level false-positive signals with unprecedented precision. The UHF-tailored T1-T2 dual-mode DMA contrast agents hold promise for elevating the accuracy of MR imaging in disease diagnosis.