Monochorionic twin pregnancies with single fetal demise are complex pregnancies with increased risk of acquired brain pathology, although the rate of brain abnormalities in our study is lower than that of other publications. iuMR in such complicated pregnancies is a useful adjuvant imaging technique that appears to detect brain pathologies better than prenatal ultrasonography.

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of the foetal brain using a rapid 3D steady-state sequence. Br J Radiol 2013;86:20130168. FULL PAPER MRI of the foetal brain using a rapid 3D steady-state sequence P D GRIFFITHS, PhD Objective: To evaluate the capacity of a rapid T 2 weighted three-dimensional (3D) sequence to diagnose foetal brain abnormalities by comparing the results with current twodimensional (2D) methods. We have also made assessments of the estimates of energy deposition using those methods. Methods: 50 pregnant females were included in this study under the guidance of the institutional review board. All their foetuses had suspected brain abnormalities on antenatal ultrasonography or were at increased risk of a brain malformation based on the results of an earlier pregnancy. All the foetuses had a routine MR protocol that includes three orthogonal plane single-shot fast-spin echoes and 2D steady-state sequences. In addition, a 3D rapid steady-state sequence of the foetal brain was performed (acquisition time approximately 40 s), and the standard and 3D sequences were reported independently and the results were compared. The specific absorption rate (SAR) predicted by the scanner was recorded in 12 cases in order to estimate the energy deposited by the three sequences. Results: The 3D rapid steady-state sequences produced diagnostic-quality images in 41/50 (82%) cases. All the failures were in second trimester foetuses (9/26-35% failure rate). There was a discrepancy between the standard report and findings using the 3D sequence in 2/41 of the foetuses with good-quality 3D imaging. The predicted SAR deposition of the 3D steady-state sequences was comparable with the single-shot fast-spin echo sequence. Conclusion: Our initial assessments of a 3D rapid steadystate sequence to image the foetus are encouraging in terms of diagnostic information and acceptable energy deposition values. The high failure rate in second trimester foetuses probably relates to the greater mobility of the smaller foetuses, and improvements in the 3D sequence are required in terms of reduced acquisition time and higher resolution. Advances in knowledge:We have shown that 3D T 2 weighted images of the foetal brain can be acquired in a clinical setting and produce diagnostic-quality imaging in a high proportion of cases. The success rate in acquiring diagnostic-quality images is related to gestational age. Good-quality images were obtained in all third trimester foetuses but only in approximately two-thirds of second trimester foetuses. This probably reflects the problem of the greater mobility of second trimester foetuses. 3D T 2 weighted acquisitions have great potential for improving the antenatal diagnosis of foetal brain abnormalities and may reduce the time that a pregnant female needs to spend on the MR scanner.MRI of the foetus while in utero (iuMR) has become a valuable adjunct to antenatal ultrasonography over the past 10-15 years, particularly in cases of suspected brain pathology [1][2][3][4][5][6]. The most common approach to iuMR is to use sectional u...

Objective: Lissencephaly is a rare disorder of cortical developmental, which usually carries increased risk of recurrence in future pregnancies. In this prospective observational study, we wished to test the hypothesis that sulcation patterns can be used to diagnose lissencephaly successfully on in utero MR (iuMR) imaging in the third-trimester but not in the late second-trimester fetus. Methods: Pregnant females were recruited into this study if they had an increased risk of fetal lissencephaly based on a fetus or child with lissencephaly in an earlier pregnancy. All females were offered serial iuMR examinations at one centre and are reported whether they had at least two examinations. The overall recurrence rate of lissencephaly was recorded along with the sulcation patterns of non-affected fetuses. Results: 19 females were recruited with 23 pregnancies. In 3/23 (13%) fetuses, lissencephaly was diagnosed on iuMR and not detected on ultrasonography. In two cases, the diagnosis of lissencephaly was made on second-trimester iuMR imaging-with certainty in one and described as "possible" in the other. Confident diagnoses of lissencephaly were made by 28-week gestation in all three cases. Four fetuses, ultimately shown not to have lissencephaly, were judged to have minor sulcation delay on secondtrimester imaging but became gestational age appropriate in the third trimester. Conclusion: iuMR imaging can identify fetal lissencephaly between 20 and 24 weeks, but false positives should be expected, particularly in the second trimester, and followup imaging later in pregnancy may be required. Advances in knowledge: It is possible to detect fetal lissencephaly between 20-and 24-week gestational age; but, it is considerably easier in the third trimester. As a result, if a fetus has an increased risk of lissencephaly on the basis of family history, it may be necessary to do serial iuMR studies to confirm normality (or abnormality) of the fetal brain.

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