Magnetic susceptibility matching at the air-tissue interface in rat lung by using a superparamagnetic intravascular contrast agent: Influence on transverse relaxation time of hyperpolarized helium-3

• Published in: Magnetic resonance in medicine Vol. 54; no. 1; pp. 28 - 33
• Main Authors: Vignaud, Alexandre, Maître, Xavier, Guillot, Geneviève, Durand, Emmanuel, de Rochefort, Ludovic, Robert, Philippe, Vivès, Véronique, Santus, Robin, Darrasse, Luc
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc., A Wiley Company 01.07.2005
• Subjects: Administration, Inhalation; Air; Algorithms; Animals; Contrast Media; Dextrans; Dose-Response Relationship, Drug; Ferrosoferric Oxide; Helium - administration & dosage; hyperpolarized helium-3; Image Enhancement - methods; Injections, Intravenous; Iron - administration & dosage; Isotopes - administration & dosage; Lung - anatomy & histology; lung MRI; Magnetic Resonance Imaging - methods; magnetic susceptibility match; Magnetite Nanoparticles; Male; Oxides - administration & dosage; rat; Rats; Rats, Sprague-Dawley; Reproducibility of Results; Sensitivity and Specificity; Surface Properties; transverse relaxation time T2cpmg; USPIO
• ISSN: 0740-3194; 1522-2594
• DOI: 10.1002/mrm.20576

Transverse relaxation of hyperpolarized helium‐3 magnetization in respiratory airways highly depends on local magnetic field gradients induced by the magnetic susceptibility difference between gas and pulmonary tissue. Fast transverse relaxation is known to be an important feature that yields information about lung microstructure and function, but it is also an essential limitation in designing efficient strategies for lung imaging. Using intravascular injections of a superparamagnetic contrast agent in rats, it was possible to increase the overall susceptibility of the perfused lung tissues and hence to match it with the gas susceptibility. The transverse decay time constant of inhaled hyperpolarized helium‐3 was measured in multiple‐spin‐echo experiments at 1.5 T as a function of the superparamagnetic contrast agent concentration in the animal blood. The time constant was increased by a factor of 3 when an optimal concentration was reached as predicted for susceptibility matching by combining intrinsic susceptibilities of tissue, blood, and gas. Magn Reson Med 54:28–33, 2005. Published 2005 Wiley‐Liss, Inc.