β Scribed by G. S. Karczmar; D. B. Tweig; T. J. Lawry; G. B. Matson; M. W. Weiner
No coin nor oath required. For personal study only.
An NMR method which makes use of a radiofrequency (RF) field gradient to detect diffusion, perfusion, or flow is demonstrated. The technique is analogous to the detection of motion using pulsed Bo gradients. The simplest form of the experiment is as follows: A spatially inhomogeneous RF field generated by a surface coil produces dispersal of magnetization in the Y Z plane. After a delay, the RF field is applied with reversed phase to restore polarization along +Z, which is then sampled using an observe pulse or pulse sequence. If molecular motion occurs during the delay period the amplitude of Z magnetization will be. reduced. The lengths of the RF pulses and the delay period are varied so that the effects of relaxation, flow, and difFusion or perfusion can be distinguished. The present study demonstrates the use of this method to detect slow fluid flow. Advantages of this method include the availability of large RF gradients, and the avoidance of eddy currents. It is suggested that the method may have application to the study of perfusion and flow in vivo.
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## Abstract This work explores a concept for motion detection in brain MR examinations using high channelβcount RF coil arrays. It applies ultrashort (<100 ΞΌsec) free induction decay signals, making use of the knowledge that motion induces variations in these signals when compared to a reference fr
This work presents a new approach toward a fast, simultaneous amplitude of radiofrequency field (B 1 ) and T 1 mapping technique. The new method is based on the ''actual flip angle imaging'' (AFI) sequence. However, the single pulse repetition time (TR) pair used in the standard AFI sequence is repl