MRI Nanoimaging: Part I

Magnetic resonance imaging (MRI) is one of the most commonly used imaging modalities with very high soft tissue contrast, excellent spatial resolution, and good penetration depth. The MRI signal intensities are based on the various water protons and on the relaxation times of T1 and T2 and spin–spin relaxation. MR nanoimaging is one of the newer concepts of imaging, which will further increase the contrast when using the inorganic nanoparticles and complexes. The main basic sequences T1 and T2 will have different relaxation rates, and due to these signal intensities, there will be two major signals, which are hyperintense and hypointense signals. The signal-to-noise ratio will be assessed to improve the accuracy of various imaging analyses. Nano-contrast agents, which provide negative contrast due to iron oxide nanoparticles or ferrites and positive contrast from gadolinium ions in different lanthanide metals, are commonly used in T1-weighted images. These lanthanide components will immobilize various nanostructured materials for the new class of contrast agents, which will have better tissue sensitivity, especially in tumors. The important aspect is to align the contrast agents having the capacity to be used as multimodality imaging. Magnetoliposomes are important multimodality contrast agents. These contrast agents are comprised of various ligands and polyethylene glycol chains, and due to this, there will be more deposition of the contrast agent. These nanoparticles will be used as different MRI contrast agents.