In MRI, the received signal can be spatially encoded by the application of magnetic field gradients that are superimposed on the uniform, main magnetic field. A number of pulse sequences have been invented to highlight differences in signal of various soft tissues. The feasibility of applying 19 Fluorine nuclear magnetic resonance (NMR) techniques in humans was demonstrated after an earlier in vivo animal study. NMR is extensively used in medicine in the form of magnetic resonance imaging. The most basic forms of MR sequences include: T1-weighted (T1W) imaging, on which fluid appears dark and fat appears bright. Oral MRI contrast agents are typically nonspecific in nature. Johnson MA, Bydder GM. The first nuclear magnetic resonance (NMR) experiments were performed about thirty-five years ago (1–3). Effect of internal motion on NMRD profiles simulated for order parameters S2 = 0.4 and S2 = 0.8 and different ZFS energies. T1-weighted sequences have traditionally been considered good for evaluation of anatomic structures. Therefore, ultrasmall lanthanide oxide nanoparticles are promising nanoparticles for use as MRI contrast agents [17]. Therefore, tissues with short T2 are dark, and those with long T2 are bright. The concept of generating images with NMR arose from Paul Lauterbur's 1972 idea of applying field gradients in all three dimensions, using back-projection methods borrowed from CT scanning to generate images. Additional external time-varying magnetic fields are applied to spatially encode the MR signal. É. Tóth, ... A.E. The phenomenon of NMR was first discovered in the 1940s and was primarily the domain of physicists ( Bloch et al. Since MRI does not use any ionizing radiation its use is recommended in preference to CT when either modality could yield the same information. Effect of the increased rotational correlation time on the proton relaxivity of MP2269, a GdIII chelate capable of noncovalent protein binding (Scheme 2). Proton excitation with an externally applied RF field is repeated at short intervals to obtain signals. Ultrasmall lanthanide metal oxide nanoparticles (Ln = Dy, Ho, Tb, Er, etc.) Their magnetic moments do not drop very far with decreasing particle diameter and by surface coating with ligand. Intra-articular contrast agents may also be administered, producing an MR arthrogram effect to enhance the evaluation of intra-articular structures such as articular cartilage, fibrocartilage, and ligaments. In musculoskeletal imaging, MR arthrography is a technique available to augment the depiction of internal derangements of joints.1 Arthrography can be either indirect (intravenous gadolinium is administered and allowed to diffuse into the joint) or direct (a dilute gadolinium solution is percutaneously injected into the joint) to provide distention of a joint, assisting in the evaluation of ligaments, cartilage, synovial proliferation, or intraarticular bodies. For example, in CE-MRA, the central contrast-defining portion of k-space may be acquired early in the scan (centric acquisition) during peak intraarterial contrast concentration to maximize arterial contrast. Proton nuclear magnetic resonance (NMR) imaging has provided a major breakthrough in diagnostic medical imaging and biomedical research. 2007), which has increased cortical volume and thickness. From both M-H and M-T curves, magnetism (superparamagnetism, paramagnetism, ferromagnetism, antiferromagnetism, and nonmagnetism), saturation magnetization (Ms), coercivity (Hc), remanence (Mr), and phase transition temperature such as Curie (TC), Niel (TN), and blocking (TB) temperatures can be determined. When the spins are tipped to the transverse plane, they all precess in phase. Developing gadolinium-free T1-weighted MRI contrast agent has been longed for. They are coated with carboxyl dextran to form spheres of 18–65-nm diameter, which are uptaken by Kupffer cells in livers. 4.10 and 4.11 is given, showing that the point of zero intensity falls together with the point where the phase shift drops from 180° to zero. The human body is primarily fat and water, both of which have many hydrogen atoms, making the human body approximately 63% hydrogen atoms. Such pattern of contrast enhancement can be obtained over a wide range of systemic doses (Lee et al. MRI is therefore safer than a CAT scan (no X-rays or other damaging radiation is used). In 2003, Lauterbur and Mansfield shared the Nobel Prize in Medicine for MRI. During 1.5-T brain and lumbar MRI scans, there were no clinically significant ventricular arrhythmias, pacemaker inhibition, or changes in threshold.29 Bailey and associates demonstrated the feasibility and safety of thoracic or cardiac MRI in an MRI conditional pacemaker.30 MRI may pose serious risks if preexisting leads are in place even if a pacemaker generator designed for MRI use is in place.