Magnetic resonance spectroscopy to detect lecithin in amniotic fluid and fetal lung

BACKGROUND: Proton magnetic resonance spectroscopy is a noninvasive technique that detects molecules within a specified region in vivo. Lecithin, the major component of surfactant, has a characteristic magnetic resonance signal, but to our knowledge, it has never been reported in fetal lung or amniotic fluid (AF). The objective of this study was to characterize the lecithin signal in utero, which could lead to a noninvasive fetal lung maturity test. METHOD: Human fetal lung and AF pockets can be identified and studied with magnetic resonance spectroscopy with the use of a 1.5-tesla Vision whole-body magnetic resonance scanner (Siemens Medical Systems; Erlangen, Germany). Spectroscopy data are collected with a single-voxel-point-resolved spectroscopy sequence. After identification of fetal anatomy with the use of scout magnetic resonance images, magnetic resonance spectroscopy of human fetal lung and AF identifies a lecithin peak. EXPERIENCE: Three healthy gravidas near term were studied and lecithin peaks were identified in all. CONCLUSION: Lecithin can be identified in vivo with the use of volume-selected proton magnetic resonance spectroscopy. Patient comfort and extremely short scan times suggest that refined magnetic resonance spectroscopy might be a safe, quick, and comfortable test of fetal lung maturity.