Lecithin can be detected by volume-selected proton MR spectroscopy using a 1.5 T whole body scanner: a potentially non-invasive method for the prenatal assessment of fetal lung maturity.

The prenatal determination of fetal lung maturity is currently assessed by chemical analysis of surfactant associated lipids from aminotic fluid obtained by amniocentesis. This is an invasive procedure with rare but occasionally serious morbidity. Magnetic resonance spectroscopy (MRS) is a non-invasive method for the in vivo localization and identification of molecules with known resonance peaks at specified chemical shifts. In this report we examine the in vitro MRS of a lecithin/saline solution as well as term and preterm amniotic fluid samples with the use of a 1.5 T whole body scanner and a flexible surface coil. We found that amniotic fluid at term demonstrates a resonance peak at 3.2 ppm which was the same as the chemical shift of lecithin in saline. The lecithin peak is not observed in preterm amniotic fluid. This demonstrates the feasibility of using MRS with a whole body scanner to detect lecithin, one of the markers for fetal lung maturity.