**1.1 Development history**

Magnetic resonance imaging (MRI) is a powerful cross-sectional diagnostic imaging modality. Its technical principle developed by Bloch and Purcell was advanced for clinical application since 1973 by Lauterbur and Mansfield [1]. MRI allows a generation of noninvasive images and a determination of detailed internal morphology and function of organs and tissues, rendering it particularly useful for detection and characterization of diseased soft tissue including solid tumors. MRI has many advantages such as the absence of ionizing radiation exposure and provides three-dimensional images with high spatial resolution and contrast. The quality of MR images, including spatial resolution, signal-to-noise ratio, and contrast-to-noise ratio (CNR), has been markedly improved in the past decades. In addition, the use of contrast agents (CAs) has been playing a crucial role in improving the detection of tumor lesions, especially brain tumors, due to a rupture of blood-brain barrier by enhancing the image contrast between normal and abnormal tissues [2, 3].
