Magnetic resonance imaging: the use of the inversion recovery sequence to display fetal morphology.

A number of reports of the potential use of magnetic resonance imaging (MRI) for the examination of the human fetus have appeared in the literature over the past four years (Smith et al, 1983; Johnson et al, 1984; Smith et al, 1984; McCarthy et al, 1985; Smith, 1985; Smith et al, 1985; Starket al, 1985).Even though the method is considered to be safe for the examination of pregnancies in the second and third trimester (NRPB, 1983), it has not gained wide acceptance as a method for examining abnormal pregnancy. This may be duein part to a reticence in examining the fetus and in part to the fact that spin-echo pulse sequences do not show sufficient morphological detail in the fetus to be more useful than ultrasound (Weinreb et al, 1986). The use of longtime-torepeat(TR), 2–0 s spin-echo sequences has been advocated but these images are often degraded by fetal motion artefacts (McCarthy et al, 1985). The use of calculated T1 images for the display of fetal fat and fetal morphology has been reported (Smith et al, 1983, 1984, 1985) but no detailed exploration ofthe use of inversion recovery sequences has been reported. The purpose of this study was to assess the potential value of different inversion recovery sequences for displaying fetal anatomy. The Joint Ethical Committee of the Grampian Health Board and the University of Aberdeen has approved protocols for the study of human pregnancy in the second and third trimester.