Ultrafast magnetic resonance imaging of central nervous system abnormalities in utero in the second and third trimester of pregnancy: comparison with ultrasound

doi:10.1016/S0306-5456(00)00115-7

British Journal of Obstetrics and Gynaecology

Volume 108, Issue 5, May 2001, Pages 519-526

British Journal of O...

https://doi.org/10.1016/S0306-5456(00)00115-7 Get rights and content

Abstract

Objective To assess the ability of ultrafast magnetic resonance imaging to visualise abnormalities in the central nervous system of third trimester fetuses in utero and to compare the results with the current ‘reference standard’ of ultrasound and postnatal imaging or post-mortem data.

Design A prospective, observational study comparing the diagnostic accuracy of two imaging methods: antenatal ultrasound and antenatal magnetic resonance with each other and postnatal or post mortem data.

Population Twenty-one pregnant women of 19–36 weeks of gestation whose fetus were thought to have a central nervous system abnormality on the basis of antenatal ultrasound. The women had either not been offered or had refused a termination and were willing to have a magnetic resonance scan.

Methods A 1.5T magnetic resonance scanner used a single shot fast spin echo sequence, in three image planes. The results were compared with the ultrasound results obtained by an experienced investigator independently. A series of 21 patients, with a range of pathologies of central nervous system, were imaged. Postnatal ultrasound and/or magnetic resonance imaging, or post-mortem data were used for additional confirmation of the pathology in all cases.

Results The magnetic resonance report was different to the ultrasound in 10/21 (47.6%), magnetic resonance provided information additional to the ultrasound in 5/21 (23.8%), ultrasound and magnetic resonance results agreed in 6/21 cases (28.6%).

Conclusion Magnetic resonance in the third trimester provides a useful adjuvant to ultrasound imaging of the fetus when assessing abnormalities of the central nervous system after 19 weeks of gestation particularly if the abnormality involves the posterior fossa.

Section snippets

Introduction.

Approximately 2% of newborn children have congenital abnormalities severe enough to produce significant medical or social problems. Developmental abnormalities of the central nervous system are among the most common congenital abnormalities that produce significant morbidity and mortality. Antenatal diagnosis of central nervous system anomalies is essential for counselling during pregnancy and making decisions about termination of pregnancy. Nationwide screening programmes have been in place

methods

The study was established with the assistance and approval of the South Sheffield ethics committee and written informed consent was obtained from each patient. Women were referred for magnetic resonance imaging in cases where a CNS abnormality had been detected on antenatal ultrasound but further anatomical clarification was required. The 21 cases in this study were imaged over a 12-month period and did not include women who opted for a termination of the pregnancy based on the ultrasound

Results

Twenty-three women were referred for magnetic resonance imaging but it was not possible to carry out in two cases. The reasons for failure were: one woman had claustrophobia, and one would not fit in the scanner. Therefore 21 women were scanned successfully, with an age range of 16–34 years (mean 24.4 years), and gestational age range of 19–36 weeks mean (27+6 weeks). All fetuses had brain imaging, and this was supplemented by spinal imaging in 10 cases. The first fetus was imaged using the

Discussion

At present the reference standard in prenatal diagnosis is ultrasound. However there are numerous limitations, including the non-specific appearances of some abnormalities and subtle parenchymal changes that are difficult to detect on ultrasound. In addition there are technical limitations including operator variability, positional problems with the fetus, and problems when there is associated oligohydramnios. The later the gestation, the harder visualisation of the fetal brain becomes. This is

Conclusion

Magnetic resonance shows a great potential for imaging congenital abnormalities, and requires further investigation for its role in organ regions other than the CNS and at earlier gestational ages. There will be greater fetal mobility in the second trimester compared with the third, due to the amount of available space but this should not be a problem with these fast imaging techniques. In addition fetal movement can still degrade the images, but only the image taken at the time of the movement

Acknowledgments

The authors would like to thank the radiographic staff at the University of Sheffield for helping image the women and the office staff for dealing with the appointments; Dr I Wilkinson for additional input on magnetic resonance physics; SPARKS charity for financial support for the imaging; and Schering Health Care Limited for some financial support of E.H.W.

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Ultrafast magnetic resonance imaging of central nervous system abnormalities in utero in the second and third trimester of pregnancy: comparison with ultrasound

Abstract

Section snippets

Introduction.

methods

Results

Discussion

Conclusion

Acknowledgments

Am J Obstet Gynecol.

Lancet

Brain Dev

Seminars in perinatology

Congenital malformations etiological factors and their role in prevention

N Engl J Med

A six year study of the antenatal detection of fetal abnormality in six Scottish health boards

Br J Obstet Gynaecol

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AJR

Magnetic Resonance imaging of the Fetus

Pediatr Radiol

In vivo MRI of the fetal brain

Neuroradiology

Fetal fast MR imaging: reproducibility, technical quality and conspicuity of anatomy

Radiology

MR imaging of the fetus by a HASTE sequence

AJR