A 13 C/ 31 P surface coil to visualize metabolism and energetics in the rodent brain at 3 Tesla.

Purpose: We constructed a ¹³ C/ ³¹ P surface coil at 3 T for studying cancer metabolism and bioenergetics. In a single scan session, hyperpolarized ¹³ C-pyruvate MRS and ³¹ P MRS was carried out for a healthy rat brain.
Methods: All experiments were carried out at 3 Tesla. The multinuclear surface coil was designed as two coplanar loops each tuned to either the ¹³ C or ³¹ P operating frequency with an LCC trap on the ¹³ C loop. A commercial volume proton coil was used for anatomical localization and B ₀ shimming. Single tuned coils operating at either the ¹³ C or ³¹ P frequency were built to evaluate the relative performance of the multinuclear coil. Coil performance metrics consisted of measuring Q factor ratio, calculating system input power using a single-pulse acquisition, and acquiring SNR and flip angle maps using 2D CSI sequences. To observe in vivo spectra, a bolus of hyperpolarized [1- ¹³ C] pyruvate was administered via tail vein. In vivo ¹³ C and endogenous ³¹ P spectra were obtained in a single scan session using 1D slice selective acquisitions.
Results: When compared with single tuned surface coils, the multinuclear coil performance showed a decrease in Q factor ratio, SNR, and transmit efficiency. Flip angle maps showed adequate flip angles within the phantom when the transmit voltage was set using an external phantom. Results show good detection of ¹³ C labeled lactate, alanine, and bicarbonate in addition to ATP from ³¹ P MRS.
Conclusions: The coil enables obtaining complementary information within a scan session, thus reducing the number of trials and minimizing biological variability for studies of metabolism and bioenergetics.
Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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