In preparation for an MRI, a patient is usually injected with a gadolinium contrast media, a substance that aids in illuminating certain features in the brain. Although the agent is generally considered safe for most, it can result in serious adverse side effects for young children and people with weak kidneys. A new study published in the journal ACS Central Science has found a way to effectively generate clear MRI images of these patient populations through using an agent consisting of organic nitroxide compounds instead of gadolinium metal.
While experimenting on mice, scientists from the Massachusetts Institute of Technology and the University of Nebraska found that BASP-ORCA1 allowed for “simultaneous MRI and NIRF imaging in vivo over time scales suitable for tumor imaging following systemic injection.” The brush-arm star polymer (BASP) nanostructure inserts a dense layer of chex nitroxides on the interface between the rigid poly (acetal) core and a hydrophilic PEG shell. BASP-ORCA1 results in a bright image, and does not wash away as fast as other alternative agents. These properties make it easy for radiologists to identify tumors and are beneficial for evaluating an anticancer drug’s effectiveness.
“This work suggests that organic radicals can be viable alternatives to metal based MRI contrast agents,” write the researchers. “And sets the stage for the development of theranostic systems that combine organic radical contrast agents with therapeutic payloads to achieve simultaneous tumor imaging and drug delivery without concerns over long-term tissue accumulation of metals.”