Fig. 2. Comparison of spectra resulting from FID and DEMz acquisition in phantoms.

Phantoms composed of ATP and NADH (A) or ATP and NAD⁺ (B) were measured. α-ATP suppression of 85% with an approximate signal loss of 22.7% for NADH and 22.9% for NAD⁺ were observed. Relative concentrations resulting from DEMz spectra of NADH (C) and NAD⁺ (D) phantoms over actual NADH and NAD⁺ concentrations of phantom compartments in mM are shown. In E and F, a series of editing echo times (TE_j) of 13.75 ms, 25.0 ms, 27.5 ms, and 30.0 ms in double echo modified z-Filter (DEMz) sequence measuring a phantom composed of 5 mM ATP and 3.5 mM NADH (E) and a phantom with 5 mM ATP and 3.5 mM NAD⁺ (F) are shown. NADH resonance intensity remains stable over this range of TE_j. $\mathrm{\alpha }$-ATP residual is smallest at TE_j 27.5 ms. Similarly, results were observed on the NAD⁺ resonance. Source data for C, D are provided as a Source Data file.