A method of performing Nuclear Magnetic Resonance (NMR) spectroscopy or Magnetic Resonance Imaging (MRI). The methods may include: a) generating a compound comprising a first nuclear species (I
1
), a second nuclear species (I
2
), a third nuclear species (S), a heteronuclear coupling asymmetry (|J
1S
−J
2S
|) and a nuclear singlet state spin order localized on I
1
and I
2
; b) transferring the nuclear singlet state spin order into heteronuclear magnetization localized on S by applying a single, non-recursive pulse sequence at a low magnetic field in the strong coupling regime of protons; and c) performing NMR spectroscopy or MRI with the compound comprising heteronuclear magnetization localized on S. The |J
1S
−J
2S
| may be non-zero. The pulse sequence may include a plurality of sequential radio frequency pulses separated by independent evolution interval. The pulse sequence may be capable of transferring at least about 75% of the nuclear singlet state spin order into heteronuclear magnetization localized on S at any |J
1S
−J
2S
| when the independent evolution intervals are optimized.
<i>In Situ</i> Detection of PHIP at 48 mT: Demonstration Using a Centrally Controlled Polarizer
作者:Kevin W. Waddell、Aaron M. Coffey、Eduard Y. Chekmenev
DOI:10.1021/ja108529m
日期:2011.1.12
Presented here is a centrally controlled, automated parahydrogen-based polarizer with in situ detection capability. A 20% polarization, corresponding to a 5 000 000-fold signal enhancement at 48 mT, is demonstrated on 2-hydroxyethyl-1-C-13-propionate-d(2,3,3) using a double-tuned antenna and pulsed polarization transfer. In situ detection is a refinement of first-generation devices enabling fast calibration of rf pulses and B-0, quality assurance of hyperpolarized contrast agents, and stand-alone operation without the necessity of high-field MR spectrometers. These features are essential for biomedical applications of parahydrogen-based hyperpolarization and for clinical translation. We demonstrate the flexibility of the device by recording C-13 signal decay due to longitudinal relaxation of a hyperpolarized contrast agent at 48 mT corresponding to 2 MHz proton frequency. This appears to be the longest recorded T-1 (101 +/- 7 s) for a C-13 hyperpolarized contrast agent in water.