³¹P transverse relaxation times of ATP in human brain in vivo

Abstract

31P MRS examinations of the brain of 10 healthy volunteers were performed to determine T2 of the coupled ATP signals by use of the localized 90 degrees-TE/2-2662-TE/2-acq frequency selective spin echo sequence for elimination of phase and intensity distortions. The T2 relaxation times obtained are much longer than usually assumed: gamma-ATP: 89 +/- 9 ms; alpha-ATP: 84 +/- 6 ms; beta-ATP: 62 +/- 3 ms.

On the use of two‐dimensional‐J NMR measurements for in Vivo proton MRS: Measurement of homonuclear decoupled spectra without the need for short echo times

“…Thus, the T, relaxation times of these metabolite signals are long enough to perform ZD-J NMR experiments. These surprisingly long T, values of several coupled resonances correspond to similar findings in in vivo 31P NMR (24).…”

PhosphorusJCoupling Constants of ATP in Human Myocardium and Calf Muscle

“…This is necessary, because experiments have shown that Fou-the experimental linewidths are far greater than the natural linewidths (see under Discussion). The chemical shifts of rier artifacts can lead to additions or subtractions of up to about 40% in neighboring voxels (25).…”

Fast imaging of phosphocreatine using a RARE pulse sequence

“…Although the T2 decay of the ATP resonances is considerably shorter than that of either Pi or PCr (4), it is desirable to start acquiring the center lines of k-space as soon as possible after excitation. This technique enhances the decay of these chemical shifts to allow acquisition of central k-space echoes soon after excitation with minimal contamination from the ATP signals.…”

“…Rapid acquisition with relaxation enhancement (RARE) (1) pulse sequences such as fast spin echo (FSE) are well suited to the direct imaging of phosphocreatine (PCr) due to its long TI and T, relaxation times (2)(3)(4). It is well known that when the refocusing pulses of a RARE sequence do not create an exact 180° flip for all spins, the signal decay is not described by the true T, relaxation time of the spins (5,6).…”