Effects of contrast agents on relaxation properties of 31 P metabolites

• Published in: Magnetic resonance in medicine 2020-10
• Main Authors: Valkovič, Ladislav, Lau, Justin Y C, Abdesselam, Ines, Rider, Oliver J, Frollo, Ivan, Tyler, Damian J, Rodgers, Christopher T, Miller, Jack J J
• Format: Article
• Language: English
• ISSN: 1522-2594

Phosphorous MR spectroscopy ( P-MRS) forms a powerful, non-invasive research tool to quantify the energetics of the heart in diverse patient populations. P-MRS is frequently applied alongside other radiological examinations, many of which use various contrast agents that shorten relaxation times of water in conventional proton MR, for a better characterisation of cardiac function, or following prior computed tomography (CT). It is, however, unknown whether these agents confound P-MRS signals, for example, 2,3-diphosphoglycerate (2,3-DPG). In this work, we quantitatively assess the impact of non-ionic, low osmolar iodinated CT contrast agent (iopamidol/Niopam), gadolinium chelates (linear gadopentetic acid dimeglumine/Magnevist and macrocyclic gadoterate meglumine/Dotarem) and superparamagnetic iron oxide nanoparticles (ferumoxytol/Feraheme) on the nuclear T and T of P metabolites (ie, 2,3-DPG), and H in water in live human blood and saline phantoms at 11.7 T. Addition of all contrast agents led to significant shortening of all relaxation times in both H and P saline phantoms. On the contrary, the T relaxation time of 2,3-DPG in blood was significantly shortened only by Magnevist (P = .03). Similarly, the only contrast agent that influenced the T relaxation times of 2,3-DPG in blood samples was ferumoxytol (P = .02). Our results show that, unlike conventional proton MR, phosphorus MRS is unconfounded in patients who have had prior CT with contrast, not all gadolinium-based contrast agents influence P-MRS data in vivo, and that ferumoxytol is a promising contrast agent for the reduction in P-MRS blood-pool signal.