Development of molecular imaging probe for dual NIR/MR imaging

Imaging utilizing the near-infrared (NIR) light has attracted numerous attention due to the possibility in the deep tissue penetration as it can overcome the light scattering and absorption of tissue components. The ultraviolet (UV) unlikely penetrates the skin, while the visible (VIS) light can be scattered or absorbed by tissue components. This penetration likely improves as the wavelength shifts beyond 1000 nm region (also called NIR-II). Fat tissues are ascribed to the scattering of UV or VIS, while others such as water, melanin, hemoglobin are greatly attributed to absorbing light. Using NIR over 1000 nm (OTN-NIR) is currently considered as a critical approach for real-time dynamical visualization of the structure and functional features of tissues anatomically with refrained effects of fatty scattering and water absorption. However, the attempts to image anatomical structure by OTN-NIR is laborious and time-consuming. Then, for facile human applying, magnetic resonance imaging (MRI) is used as a guiding technique to localize the sites of interest. MRI is considered the most beneficial imaging technique without ionizing radiation which provides images with high resolution, preeminent tissue contrast. MRI also can visualize a large volume such as the human body to the few millimeter objects with great signal-to-noise ratio as well as contrast-to-noise ratio. This review highlights the design of imaging probe for multimodal NIR/MR imaging, including the potential applications.