Molecular imaging has become a rapidly evolving field used in various applications to target macromolecules and biological process [1,2]. Various imaging systems, such as single photon emission computed tomography (SPECT), positron emission tomography (PET), computerized tomography (CT), and magnetic resonance imaging (MRI), use non-invasive techniques that provide disease-specific information through diagnostic imaging. Early detection of disease demonstrates the potential benefit of these systems. MRI, specifically, has evolved into one of the most powerful imaging techniques in diagnostic clinical medicine and biomedical research [1-3]. MRI provides excellent soft tissue and functional information as well as high resolution (< 1 mm) and good depth penetration (> 10 cm). However, the primary disadvantage of MRI is its low sensitivity and detection of targeted process compared to other molecular imaging modes. In order to overcome this disadvantage, signal amplification strategies, such as development of ultra-sensitive MR contrast agents, are employed in order to induce a different signal intensity that generates a higher contrast from the surrounding non-targeted tissue.
展开▼
