Figure 2.

Neonate with nonketotic hyperglycinemia. Proton MRIs (right) and spectra (left) obtained from an infant with nonketotic hyperglycinemia. T1-weighted images with voxel location (white boxes) of the MR spectroscopy showing all three reconstructed planes (top, sagittal; middle, coronal; bottom, axial). The T1-weighted images were acquired with a 3D gradient-echo pulse sequence with TR/TE of 8.2/3.8 ms, FOV 150 × 150 mm, 80 slices, section thickness of 1mm, no gap, and an imaging matrix of 160 × 160. Short (TE 35 ms) and long (TE 144 ms) proton (1H) MR spectra obtained from the parietal show a prominent singlet at 3.55 ppm (arrow), which is assigned to glycine and an elevated peak at 1.28 ppm (arrow), which is assigned to lactate. Lactate is visible at TE 35 as an upright peak, at TE 144 as an inverted peak, and at TE 288 ms as an upright peak. This change in lactate with echo time is a way to identify lactate due to its j-modulation properties as a function of echo time (which causes the inversion of the peak at 1.33ppm at TE 144 ms).