MRI with Gadolinium-Based Nanoparticles - Nanotechnology for Biomedical Imaging and Diagnostics - page 216

8

MRI wIth GadolInIuM-Based
nanopaRtIcles

François Guérard, Geoffrey L. Ray, and Martin W. Brechbiel
Radioimmune & Inorganic Chemistry Section, Radiation Oncology Branch, NCI,
National Institutes of Health, Bethesda, MD, USA

8.1 IntRoductIon

Magnetic resonance imaging (MRI) is a powerful tool that has provided scientists
and clinicians with the ability to acquire in vivo images of anatomy and physiology
in animals and humans. This imaging tool has become increasingly popular in experi-
mental molecular imaging and clinical radiology because it is noninvasive and capable
of producing three-dimensional representations of opaque organisms with high spatial
and high temporal resolution. Over the past two decades, MRI has become a valuable
technique for medical diagnostics providing excellent soft tissue contrast with submilli-
meter resolution on clinical scanners while not having to employ of ionizing radiation.
MRI, with the help of a contrast agent (CA), can eliminate painful, invasive proce-
dures and provide diagnostic information earlier in the clinical evaluation. Currently,
40-50% of all clinical MR exams utilize contrast media. While instrumentation and tech-
niques continue to improve image quality, CAs can dramatically highlight anatomic and
pathologic features of interest. Over the last 25 years, gadolinium (Gd 3+ )-based MR CAs
have been developed to enhance signal of water in tissues by altering proton relaxation
properties, and the ideal characteristics of Gd 3+ made it the most used CA in MRI exam-
inations. However, improvements of the sensitivity of Gd 3+ -based CA are still required.
A number of Gd 3+ -based nanoparticles under investigation could fulfill the need of more
sensitive and safer agents and could be part of the next generation of CA for MRI.