B1-insensitive T2 preparation for improved coronary magnetic resonance angiography at 3 T

✍ Scribed by Reza Nezafat; Matthias Stuber; Ronald Ouwerkerk; Ahmed M. Gharib; Milind Y. Desai; Roderic I. Pettigrew

• Book ID: 102956257
• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 740 KB
• Volume: 55
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.20835

✦ Synopsis

Abstract

At 3 T, the effective wavelength of the RF field is comparable to the dimension of the human body, resulting in B~1~ standing wave effects and extra variations in phase. This effect is accompanied by an increase in B~0~ field inhomogeneity compared to 1.5 T. This combination results in nonuniform magnetization preparation by the composite MLEV weighted T~2~ preparation (T~2~ Prep) sequence used for coronary magnetic resonance angiography (MRA). A new adiabatic refocusing T~2~ Prep sequence is presented in which the magnetization is tipped into the transverse plane with a hard RF pulse and refocused using a pair of adiabatic fast‐passage RF pulses. The isochromats are subsequently returned to the longitudinal axis using a hard RF pulse. Numerical simulations predict an excellent suppression of artifacts originating from B~1~ inhomogeneity while achieving good contrast enhancement between coronary arteries and surrounding tissue. This was confirmed by an in vivo study, in which coronary MR angiograms were obtained without a T~2~ Prep, with an MLEV weighted T~2~ Prep and the proposed adiabatic T~2~ Prep. Improved quantitative and qualitative coronary MRA image measurement was achieved using the adiabatic T~2~ Prep at 3 T. Magn Reson Med, 2006. Published 2006 Wiley‐Liss, Inc.