In vivo proton observed carbon edited (POCE) ¹³ C magnetic resonance spectroscopy of the rat brain using a volumetric transmitter and receive-only surface coil on the proton channel

Purpose: In vivo carbon-13 (¹³ C) MR spectroscopy (MRS) is capable of measuring energy metabolism and neuroenergetics, noninvasively in the brain. Indirect (¹ H-[¹³ C]) MRS provides sensitivity benefits compared with direct ¹³ C methods, and normally includes a ¹ H surface coil for both localization and signal reception. The aim was to develop a coil platform with homogenous B1+ and use short conventional pulses for short echo time proton observed carbon edited (POCE) MRS.

Methods: A ¹ H-[¹³ C] MRS coil platform was designed with a volumetric resonator for ¹ H transmit, and surface coils for ¹ H reception and ¹³ C transmission. The Rx-only ¹ H surface coil nullifies the requirement for a T/R switch before the ¹ H preamplifier; the highpass filter and preamplifier can be placed proximal to the coil, thus minimizing sensitivity losses inherent with POCE-MRS systems described in the literature. The coil platform was evaluated with a PRESS-POCE sequence (TE = 12.6 ms) on a rat model.

Results: The coil provided excellent localization, uniform spin nutation, and sensitivity. ¹³ C labeling of Glu-H4 and Glx-H3 peaks, and the Glx-H2 peaks were observed approximately 13 and 21 min following the infusion of 1-¹³ C glucose, respectively.

Conclusion: A convenient and sensitive platform to study energy metabolism and neurotransmitter cycling is presented. Magn Reson Med 79:628-635, 2018. © 2017 International Society for Magnetic Resonance in Medicine.