Stability of MRI contrast agents in high-energy radiation of a 1.5T MR-Linac.
BACKGROUND
Gadolinium-based contrast is often used when acquiring MR images for radiation therapy planning for better target delineation. In some situations, patients may still have residual MRI contrast agents in their tissue while being treated with high-energy radiation. This is especially true when MRI contrast agents are administered during adaptive treatment replanning for patients treated on MR-Linac systems.


PURPOSE
The purpose of this study was to analyze the molecular stability of MRI contrast agents when exposed to high energy photons and the associated secondary electrons in a 1.5T MR-Linac system. This was the first step in assessing the safety of administering MRI contrast agents throughout the course of treatment.


MATERIALS AND METHODS
Two common MRI contrast agents were irradiated with 7 MV photons to clinical dose levels. The irradiated samples were analyzed using liquid chromatography-high resolution mass spectrometry to detect degradation products or conformational alterations created by irradiation with high energy photons and associated secondary electrons.


RESULTS
No significant change in chemical composition or displacement of gadolinium ions from their chelates was discovered in samples irradiated with 7 MV photons at relevant clinical doses in a 1.5T MR-Linac. Additionally, no significant correlation between concentrations of irradiated MRI contrast agents and radiation dose was observed.


CONCLUSION
The chemical composition stability of the irradiated contrast agents is promising for future use throughout the course of patient treatment. However, in vivo studies are needed to confirm that unexpected metabolites are not created in biological milieus.
['Wang|Jihong|J|', 'Salzillo|Travis|T|', 'Jiang|Yongying|Y|', 'Mackeyev|Yuri|Y|', 'David Fuller|Clifton|C|', 'Chung|Caroline|C|', 'Choi|Seungtaek|S|', 'Hughes|Neil|N|', 'Ding|Yao|Y|', 'Yang|Jinzhong|J|', 'Vedam|Sastry|S|', 'Krishnan|Sunil|S|']
D003287:Contrast Media D006801:Humans D008279:Magnetic Resonance Imaging D010315:Particle Accelerators D011880:Radiotherapy Planning, Computer-Assisted D011882:Radiotherapy, High-Energy
Mass spectrometry Gadolinium Contrast media Magnetic resonance imaging Radiotherapy