Next Generation MRI Contrast Agents
Dr. Xiao-an Zhang
Department of Chemistry
University of Toronto
Wednesday, February 12, 2014
C2-361 (Reading Room)
Abstract: Magnetic resonance imaging (MRI) is a noninvasive and versatile imaging modality that is increasingly applied in clinical diagnosis and basic biomedical research to obtain anatomic and functional information of living objects. Conventional MRI relies on 1H NMR signal mainly from water, the most abundant molecule in vivo. The contrast and sensitivity of MRI can be improved by administration of paramagnetic MRI contrast agent (CA), which can shorten the nuclear spin relaxation time (T1or T2) of water protons. The current clinical MRI T1 CAs are predominantly based on low molecular weight gadolinium (Gd) complexes, which typically exhibit lower relaxivity at higher magnetic fields. Recently, several Gd CAs have been implicated in nephrogenic systemic fibrosis (NSF), a severe side effect found in related to Gd toxicity. Therefore, safer and more efficient MRI CAs are highly desirable.
I will describe our recent efforts on developing Gd-free contrast agents with high sensitivity, low toxicity and optimized pharmacokinetic properties. In addition, new strategies in developing “smart” molecular probes for MRI and NMR, which are responsive to certain molecular and cellular events, such as enzyme activity or pH changes, will also be discussed. These next generation contrast agents have great potential to be applied to detect diseases at early stage and to monitor the efficacy of treatment with high sensitivity and specificity.