Finite RF pulse correction on DESPOT2.
Magnetization transfer and finite radiofrequency (RF) pulses affect the steady state of balanced steady state free precession. As quantification of transverse relaxation (T2) with driven equilibrium single pulse observation of T2 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 (TRF/TR≪1) leads to considerable magnetization transfer effects, whereas prolonged RF pulses (TRF/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 T2 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 T2 dependency on the RF pulse duration. A reduction of the variation in obtained T2 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 T2 values using elongated RF pulses.
Department of Medical Radiology, Division of Radiological Physics, University of Basel Hospital, Basel, Switzerland. henk-joost.crooijmans@unibas.ch
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Scheffler
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Bieri
D000465:Algorithms; D016477:Artifacts; D001921:Brain / Q000033:anatomy & histology*; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D019047:Phantoms, Imaging; D011846:Radio Waves; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012815:Signal Processing, Computer-Assisted