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Updated: Jan 30, 2026

Hyperpolarized Xenon for NMR and MRI Applications
Published on: September 6, 2012
Hyperpolarized [15N]nitrate as a potential long lived hyperpolarized contrast agent for MRI
Ayelet Gamliel1, Sivaranjan Uppala1, Gal Sapir1
1Department of Radiology, Hadassah Medical Center, Hebrew University of Jerusalem, The Faculty of Medicine, Jerusalem, Israel.
Abstract:
Reports on gadolinium deposits in the body and brains of adults and children who underwent contrast-enhanced MRI examinations warrant development of new, metal free, contrast agents for MRI. Nitrate is an abundant ion in mammalian biochemistry and sodium nitrate can be safely injected intravenously. We show that hyperpolarized [15N]nitrate can potentially be used as an MR tracer. The 15N site of hyperpolarized [15N]nitrate showed a T1 of more than 100 s in aqueous solutions, which was prolonged to more than 170 s below 20 °C. Capitalizing on this effect for polarization storage we obtained a visibility window of 9 min in blood. Conversion to [15N]nitrite, the bioactive reduced form of nitrate, was not observed in human blood and human saliva in this time frame. Thus, [15N]nitrate may serve as a long-lived hyperpolarized tracer for MR. Due to its ionic nature, the immediate applications appear to be perfusion and tissue retention imaging.
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