Figure 3.

H¹MRS artifacts at intermediate TE (135 ms, 1.5T). Spectrum of a 5-year-old child with mild psychomotor retardation in (A) characterized by a noisy fluctuating baseline with an abnormally high Cr₂ peak at 3.93 ppm (red thick arrow, red dotted lines); motion artifacts cause increased linewidths, overall frequency shifts and decreased quality of water suppression: “broadening” the spectrum to the left to examine the 6 to 4 ppm interval (B) reveals bad water suppression (peak at 4.7 ppm labeled in blue) as the cause of Cr₂ overestimation and of substantial loss of information, particularly in the 3.5–4 ppm range. In case (C), gross bulk motion of a 5-month-old infant with epilepsy generates a doubling of all singlet peaks (thin yellow arrows) and an overlap of Cr₁ and tCho resonances. “Spurious” radio frequency signals led to 3 “ghost” peaks in the spectrum of a 2 months preterm infant (dotted yellow arrows in D): ghost signals are partially “out-of-phase” (below the baseline) and don’t have to be mistaken for additional pathologic peaks. In (E) and (F) outer volume Lip contaminations in a 13-year-old autistic boy are shown: Lip signals from the adjacent left parietal scalp are characterized in (E) by a different phase than the signal from within the VOI; this “out-of-phase” Lip signal (thick orange arrow) could be mistaken for an inverted Lac signal looking at the automatic peak assignment. Inspection of the contiguous voxel (F), showing the more classical “in-phase” signal seen at 1.3 (thick yellow arrow) and 0.9 ppm, confirms that selection pulses have excited also the spins outside the targeted VOI. Acronyms and abbreviations are shown in Appendix 1.