Dual Contrast Agents: A New Hope for Multimodal Imaging

ABSTRACT No single imaging modality currently achieves the combined requirements of high spatial resolution, molecular sensitivity, and deep tissue penetration. Dual contrast agents offer a better strategy to overcome these limitations by integrating complementary signal mechanisms within a single platform. Here, we establish a structure–property–performance framework that connects material design with imaging output and biological behavior across major modality pairings, including MRI–optical (Magnetic Resonance Imaging), MRI‐PET/SPECT (Magnetic Resonance Imaging‐ F and single photon emission computed tomography), and CT‐optical (Computed Tomography‐Optical) systems. We identify key governing constraints such as signal interference, sensitivity mismatch, and size‐dependent pharmacokinetics and show how these emerge from nanoscale design and surface chemistry. Despite significant progress, translation remains hindered by limited predictability, safety concerns, and manufacturing complexity. This review highlights that quantitatively driven, integrative design strategies are essential to transform dual contrast agents from experimental constructs into clinically reliable tools.