Finite RF pulse correction on DESPOT2

✍ Scribed by H. J. A. Crooijmans; K. Scheffler; O. Bieri

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 424 KB
• Volume: 65
• Category: Article
• ISSN: 0740-3194
• DOI: 10.1002/mrm.22661

✦ Synopsis

Magnetization transfer and finite radiofrequency (RF) pulses affect the steady state of balanced steady state free precession. As quantification of transverse relaxation (T 2 ) with driven equilibrium single pulse observation of T 2 is based on two balanced steady state free precession acquisitions, both effects can influence the outcome of this method: a short RF pulse per repetition time (T RF /TR ( 1) leads to considerable magnetization transfer effects, whereas prolonged RF pulses (T RF /TR > 0.2) minimize magnetization transfer effects, but lead to increased finite pulse effects. A correction for finite pulse effects is thus implemented in the driven equilibrium single pulse observation of T 2 theory to compensate for reduced transverse relaxation effects during excitation. It is shown that the correction successfully removes the driven equilibrium single pulse observation of T 2 dependency on the RF pulse duration. A reduction of the variation in obtained T 2 from over 50% to less than 10% is achieved. We hereby provide a means of acquiring magnetization transfer-free balanced steady state free precession images to yield accurate T 2 values using elongated RF pulses. Magn Reson Med 65:858-862, 2011. V