Simultaneous and interleaved acquisition of NMR signals from different nuclei with a clinical MRI scanner

Abstract

Purpose: Modification of a clinical MRI scanner to enable simultaneous or rapid interleaved acquisition of signals from two different nuclei. Methods: A device was developed to modify the local oscillator signal fed to the receive channel(s) of an MRI console. This enables external modification of the frequency at which the receiver is sensitive and rapid switching between different frequencies. Use of the device was demonstrated with interleaved and simultaneous 31 P and 1 H spectroscopic acquisitions, and with interleaved 31 P and 1 H imaging. Results: Signal amplitudes and signal-to-noise ratios were found to be unchanged for the modified system, compared with data acquired with the MRI system in the standard configuration. Conclusion: Interleaved and simultaneous 1 H and 31 P signal acquisition was successfully demonstrated with a clinical MRI scanner, with only minor modification of the RF architecture. While demonstrated with 31 P, the modification is applicable to any detectable nucleus without further modification, enabling a wide range of simultaneous and interleaved experiments to be performed within a clinical setting.

Magnetic Resonance Imaging of Phosphocreatine and Determination of BOLD Kinetics in Lower Extremity Muscles using a Dual-Frequency Coil Array

“…We combined the coil with efficient pulse sequences, (i.e., 31 P-FLORET) to measure PCr kinetics following exercise with a 6-s temporal resolution. To the best of our knowledge, this temporal resolution is the highest achieved with a volumetric imaging pulse sequence, and it is comparable to the resolution obtained using unlocalized spectroscopy 11 12 33 .…”

“…Our array additionally provided 1 H imaging and B 0 shimming capabilities with performance that was similar to that of a clinical device. This development enabled us to create comprehensive multinuclear MR protocols that can minimize experimental variability by avoiding subject repositioning, which reduces scan time 36 , as well as enable interleaved or simultaneous multinuclear acquisition using specialized pulse sequences and back-end RF hardware 33 37 38 .…”

X‐nuclei imaging: Current state, technical challenges, and future directions

“…The capability of performing these techniques depends partly on the vendor. For the scanners of one vendor, hardware elements additional to sequence modifications are necessary . For the scanners of another vendor, a software framework enabling interleaved acquisition in combination with double‐resonant coils has been presented .…”

Simultaneous proton magnetic resonance fingerprinting and sodium MRI

“…Normally, all signals are demodulated using the same local oscillator (LO) to obtain an appropriate intermediate frequency (IF) suitable for digitization with our ADCs. To enable simultaneous recording of sodium and proton signals, we externally modified the LO for the sodium receive channels using a frequency generator (Figure ), as described in Meyerspeer et al The appropriate LO frequency was calculated as follows (Equation ):…”

“…Over the years, several simultaneous imaging strategies have been proposed to help reduce total exam time and avoid image misalignment. The idea of simultaneous multinuclear imaging can be traced back to the 1980s, but the first truly simultaneous implementations did not appear until this decade . Despite these exciting developments, simultaneous multinuclear MRI has not yet become mainstream.…”