Magnetic resonance in medicine : official journal of the Society of Magnetic Resonance in Medicine
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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 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.
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Split-blade diffusion-weighted periodically rotated overlapping parallel lines with enhanced reconstruction (DW-PROPELLER) was proposed to address the issues associated with diffusion-weighted echo planar imaging such as geometric distortion and difficulty in high-resolution imaging. The major drawbacks with DW-PROPELLER are its high SAR (especially at 3T) and violation of the Carr-Purcell-Meiboom-Gill condition, which leads to a long scan time and narrow blade. ⋯ In this work, a new calibration scheme is proposed for k-space-based parallel imaging method without the need of additional calibration data, which results in a wider, more stable blade. The in vivo results show that this technique is very promising.