Transverse relaxation in the rotating frame induced by chemical exchange

The time-dependence of exchange-induced relaxation during modulated radio frequency pulses

“…Preliminary work in this regard has already appeared in print [2]. Since the formalism developed is quite general, the resulting method of development should be of use for a wide class of ''shaped pulses'' [9].…”

“…This also entailed the total neglect of relaxation processes during the pulse. In more recent applications, the duration of pulses has increased to the millisecond order of magnitude, and the use of long trains of such pulses is now commonplace [1,2]. This means that current experimental protocols now demand that relaxation during pulses cannot be neglected.…”

“…Here, it has been found that the introduction of time-dependent relaxation functions can be successfully used to simulate adiabatic pulses of the hyperbolic secant HSn family [2,3]. The concept of time-dependent relaxation functions is not new and had been developed by many investigators from the very beginning of the NMR formalism [4][5][6].…”

About the origins of NMR diffusion-weighting induced by frequency-swept pulses

“…This property has for example been exploited to perform slice or volume selection, such as in the LASER spectroscopy sequence [2], in the Pseudo-LASER spectroscopic imaging sequence [3] or in various imaging sequences [4][5][6][7]. Furthermore, trains of adiabatic pulses may be used to generate contrasts based on relaxation in the rotating frame [8,9].…”

Experimental validation of a T2ρ transverse relaxation model using LASER and CPMG acquisitions

“…Using an adiabatic CP-type sequence, Kavec et al [19] observed unique DA contrast in post-stroke brain tissue. In addition to dynamic averaging, the generation of rotating frame transverse relaxation contrast (T 2q ) was demonstrated by Michaeli et al [11,20] in a CP spin-echo sequence consisting of a series of hyperbolic secant (HSn) adiabatic full passage pulses, with no delay between pulses.…”