Quantitative T1ρ and adiabatic Carr–Purcell T2 magnetic resonance imaging of human occipital lobe at 4 T

✍ Scribed by Heidi I. Gröhn; Shalom Michaeli; Michael Garwood; Risto A. Kauppinen; Olli H. J. Gröhn

• Publisher: John Wiley and Sons
• Year: 2005
• Tongue: English
• Weight: 461 KB
• Volume: 54
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.20536

✦ Synopsis

Abstract

The feasibility of performing quantitative T~1ρ~ MRI in human brain at 4 T is shown. T~1ρ~ values obtained from five volunteers were compared with T~2~ and adiabatic Carr–Purcell (CP) T~2~ values. Measured relaxation time constants increased in order from T~2~, CP‐T~2~, T~1ρ~ both in white and gray matter, demonstrating differential sensitivities of these methods to dipolar interactions and/or proton exchange and diffusion in local microscopic field gradients, which are so‐called dynamic averaging (DA) processes. In occipital lobe, all relaxation time constants were found to be higher in white matter than in gray matter, demonstrating contrast denoted as an “inverse transverse relaxation contrast.” This contrast persisted despite changing the delay between refocusing pulses or changing the magnitude of the spin‐lock field strength, which suggests that it does not originate from DA, as might be induced by the presence of Fe, but rather is related to dipolar interactions in the brain tissue. Magn Reson Med 54:14–19, 2005. © 2005 Wiley‐Liss, Inc.