A sensitive PARACEST contrast agent for temperature MRI: Eu3+-DOTAM-glycine (Gly)-phenylalanine (Phe)
✍ Scribed by Alex X. Li; Filip Wojciechowski; Mojmir Suchy; Craig K. Jones; Robert H.E. Hudson; Ravi S. Menon; Robert Bartha
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 437 KB
- Volume
- 59
- Category
- Article
- ISSN
- 0740-3194
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✦ Synopsis
Abstract
Tissue temperature is a fundamental physiological parameter that can provide insight into pathological processes. The purpose of this study was to develop and characterize a novel paramagnetic chemical exchange saturation transfer (CEST) agent suitable for in vivo temperature mapping at 9.4T. The CEST properties of the europium (Eu^3+^) complex of the DOTAM‐Glycine (Gly)‐Phenylalanine (Phe) ligand were studied in vitro at 9.4T as a function of temperature, pH, and agent concentration. The transfer of magnetization (CEST effect) from the bound water to bulk water pools was ∼75% greater for Eu^3+^‐DOTAM‐Gly‐Phe compared to Eu^3+^‐DOTAM‐Gly at physiologic temperature (38°C) and pH (7.0 pH units) when using power level sufficiently low for in vivo imaging. Unlike Eu^3+^‐DOTAM‐Gly, whose CEST effect decreased with increasing temperature in the physiologic range, the CEST effect of Eu^3+^‐DOTAM‐Gly‐Phe was optimal at body temperature. A strong linear dependence of the chemical shift of the bound water pool on temperature was observed (0.3 ppm/°C), which was insensitive to pH and agent concentration. Temperature maps with SDs < 1°C were acquired at 9.4T in phantoms containing: 1) phantom A, an aqueous solution of 10 mM Eu^3+^‐DOTAM‐Gly‐Phe; 2) phantom B, 5% bovine serum albumin (BSA) with 15 mM Eu^3+^‐DOTAM‐Gly‐Phe; and 3) phantom C, mouse brain tissue with 4 mM Eu^3+^‐DOTAM‐Gly‐Phe. The temperature sensitivity combined with the high CEST effect observed at low concentration using low saturation power (B~1~) suggests this compound may be a good choice for in vivo temperature mapping at 9.4T. Magn Reson Med 59:374–381, 2008. © 2008 Wiley‐Liss, Inc.