Liver, meconium, haemorrhage: the value of T1-weighted images in fetal MRI.
BACKGROUND: Ultrafast T2-weighted (T2-W) MRI sequences are currently considered a routine technique for fetal MR imaging. Limited experience exists with fetal T1-weighted (T1-W) imaging techniques. OBJECTIVE: To determine MRI patterns of some fetal abdominal or haemorrhagic disorders with particular respect to the diagnostic value of T1-W images. MATERIALS AND METHODS: In addition to standard T2-W single-shot sequences, T1-W single-shot and/or multislice sequences were employed in 25 MR examinations performed in 23 fetuses between 20 and 36 weeks of gestation for more detailed assessment of liver, meconium-filled digestive tract, haemorrhage, or further characterization of a fetal abdominal mass. Diagnostic value and presence of motion artefacts on T1-W images was recorded in each case. RESULTS: T1-W images enabled superior delineation of fetal liver and large intestine. They provided additional diagnostic information in 9 (39%) of 23 fetuses. One false-positive and one false-negative MRI diagnosis of malrotation anomaly were encountered. Use of single-shot T1-W sequences reduced the occurrence of motion artefacts in 64%. CONCLUSION: Our results suggest that the specific signal properties of methaemoglobin, meconium and liver are sufficiently important for T1-W sequences to become a routine part of fetal MRI protocols when dealing with digestive tract anomalies, diaphragmatic and abdominal wall defects, intraabdominal masses, and fetal haemorrhage.