Abstract
SUMMARY: In the foreseeable future, the MI field could greatly assist neuroradiologists. Reporter molecules provide information on specific molecular or cellular events that could not only aid diagnosis but potentially differentiate stages of disorders and treatments. To accomplish this, reporter molecules literally need to pass a barrier, the BBB, which is designed to repel nonessential molecules from the brain. Although this is not a trivial task, several transport systems could be tricked into guiding molecules into the brain. The noninvasive nature in conjunction with a wide availability makes MR imaging particularly suitable for longitudinal neurologic imaging studies. This review explains the principles of MR imaging contrast, delineates different types of reporter molecules, and describes strategies to transport reporters into the brain. It also discusses recent advances in MR imaging hardware, pulse sequences, the development of targeted reporter probes, and future directions of the MR neuroimaging field.
Abbreviations
- AD
- Alzheimer disease
- BBB
- blood-brain barrier
- CA
- contrast agent
- CEST
- chemical exchange saturation transfer
- CLIO
- cross-linked iron oxide
- CNS
- central nervous system
- DMSO
- dimethyl sulfoxide
- Eu-DOTA
- europium tetra-azacyclododecane tetraacetic acid
- 18F
- fluorine-18
- 19F
- fluorine-19
- FDG
- fluorodeoxyglucose
- Gd
- gadolinium
- Gd3+
- gadolinium 3+
- 1H-MR imaging
- proton MR imaging
- LRP
- lysine rich protein
- MI
- molecular imaging
- MION
- monocrystalline iron oxide nanoparticle
- Mn2+
- manganese 2+
- MRS
- magnetic resonance spectroscopy
- MW
- molecular weight
- 31P
- phosphorus-31
- PARACEST
- chemical exchange saturation transfer using paramagnetic ions
- PEG
- polyethylene glycol
- PET
- positron-emission tomography
- RNA
- ribonucleic acid
- SPIO
- superparamagnetic iron oxide
- T1
- longitudinal relaxation time
- T2
- transverse relaxation time due to spin-spin interactions (irreversible effect)
- T2*
- transverse relaxation time due to spin-spin interactions and local inhomogeneities (partly reversible)
- USPIO
- ultrasmall superparamagnetic iron oxide
- Copyright © American Society of Neuroradiology
Indicates open access to non-subscribers at www.ajnr.org