Fig. 4.

Representative ¹³C MRSI data collected every 9 s following the injection of HP [1-¹³C]pyruvate in a pregnant rat (E20), starting ca. 4 s after completion of the metabolite’s injection. (A) The ¹³C MRSI series recorded on a 10-mm-thick slice with a 1.5 × 1.5 mm² in-plane resolution, overlaid on the corresponding middle slice ¹H NMR image. The upper ¹³C images arise at the chemical shift of [1-¹³C]pyruvate and the lower series at the [1-¹³C]lactate shift. The dashed curves highlight placentas from different fetuses; “A” indicates the strong signal associated to a maternal artery, and “N” indicates a region taken for noise estimation. The top left spot observed in the initial lactate image is centered in one of the maternal kidneys. (B) The ¹³C signal intensities extracted as a function of postinjection time from the voxels highlighted in the ¹³C images. The lines are meant to help visualizing the changes; signals were normalized as indicated, to fit in a common plot.