In vivo (1)H magnetic resonance spectroscopy of amniotic fluid and fetal lung at 1.5 T: technical challenges.

PURPOSE: To identify the major technical challenges associated with in utero single-voxel proton spectroscopy of amniotic fluid and fetal lung and to evaluate the feasibility of performing in utero fetal spectroscopy for fetal lung maturity testing.

MATERIALS AND

METHODS

Fetal magnetic resonance (MR) spectroscopy of amniotic fluid and fetal lung were performed at 1.5 T in 8 near-term pregnant women. Presence/absence of lactate and choline peaks was tabulated. Ex vivo spectra were obtained from amniotic fluid samples to investigate and refine sequence parameters.

RESULTS

Spectroscopy failed in 3 of 8 cases due to maternal discomfort (n = 1) or fetal gastroschisis (n = 2). Both fetal motion and low signal-to-noise ratio were limiting factors for the remaining 5 clinical in vivo studies at 1.5 T. Ex vivo and in vivo studies suggested feasibility for detecting lactate from amniotic fluid within a reasonable clinical scan time (4-5 minutes). Lactate was detected in 3 of 5 patients. Choline detection was limited and was detected in 1 patient.

CONCLUSION

Minor motion effects can be overcome but continuous fetal motion is problematic. Lactate detection seems clinically feasible, but choline detection requires additional technical development and, potentially, further imaging at a higher field strength because of the low signal-to-noise ratio at 1.5 T.