[1-13C]lactate Signal Derived from Hyperpolarized [1-13C]pyruvate Originates from the Brain, Not from the Blood.

Isabelle Iltis¹, Dinesh Kumar Deelchand¹, Malgorzata Marjanska¹, Gregor Adriany¹, Manda Vollmers¹, Kamil Ugurbil¹, Pierre-Gilles Henry¹

Recently, we have shown detection of [1-¹³C]lactate in the normal brain in vivo after injection of hyperpolarized [1-¹³C]pyruvate. However, the spatial origin of the detected [1-¹³C]lactate signal has been a matter of debate. In the present work, a coil specifically designed to detect ¹³C resonances in the carotid of anesthetized, living rats was used to detect signals from the blood. We show that no lactate signal is detected in the carotid after injection of hyperpolarized [1-¹³C]pyruvate, hereby demonstrating that the lactate signal observed in the brain originates from tissue metabolism.