In-utero MRI more accurate than ultrasound for diagnosing fetal brain abnormalities
This finding suggests that any fetus with a suspected brain abnormality on ultrasound should have iuMRI to better inform counseling and management decisions.
In-utero MRI (iuMRI) improves diagnostic accuracy and confidence for fetal brain anomalies better than ultrasound alone, according to a study published in the Lancet.
Paul D Griffiths, FRCR, and colleagues identified 570 women between July 29, 2011, and August 31, 2014, whose fetus had a brain abnormality detected by ultrasound at a gestational age of 18 weeks or more, had no contraindications to iuMRI, and consented to enter the study. Recruitment was from 16 fetal medicine units in the UK, primarily conducted at the University of Sheffield's MRI facility. Women were recruited by being offered an iuMRI scan after having had a detailed ultrasound scan suggesting a brain abnormality in the fetus.
The prognostic information given to participants after the ultrasound was categorized as: normal (no worse than the risk to a fetus without a demonstrable brain abnormality), favorable (normal neurological outcome expected in >90% of cases), intermediate (normal neurological outcome expected in 50 to 90% of cases), poor (normal neurological outcome expected in <50% of cases), or unknown. Clinicians also ranked their certainty of diagnosis as: “Very unsure,” “Unsure,” “Equivocal,” “Confident,” and “Highly Confident.”
Women carrying a fetus suspected of having a brain anomaly on ultrasound underwent iuMRI within 14 days of ultrasound. To reduce potential bias to show improvements in the diagnostic accuracy of iuMRI, the time between ultrasound and iuMRI should be as short as reasonably possible, noted the investigators.
The cohort was subdivided by gestation into the 18 weeks to <24 weeks fetus (369 women) and 24 weeks or older fetus (201 women). Diagnostic accuracy was improved by 23% in the 18 to <24 weeks group and 29% in the 24 weeks and older group. The overall diagnostic accuracy was 68% for ultrasound and 93% for iuMRI. Dominant diagnoses were reported with high confidence on ultrasound in 465 (82%) of 570 cases, compared with 544 (94%) of 570 cases on iuMRI. IuMRI had patient acceptability with at least 95% of women saying that they would have an iuMRI if a future pregnancy were complicated by a fetal brain abnormality.
This finding suggests that any fetus with a suspected brain abnormality on ultrasound should have iuMRI to better inform counseling and management decisions. “We found that adding iuMRI to the diagnostic pathway increased the diagnostic accuracy for 92% for fetuses younger than 24 weeks and 94% thereafter,” said the authors. “This, together with encouraging findings of other studies described later, suggests that iuMRI significantly increases the accuracy of fetal brain diagnoses compared to ultrasound alone in all fetuses 18 weeks and older.”
- Griffiths PD, Bradburn M, Campbell MJ, et al. Use of MRI in the diagnosis of fetal brain abnormalities in utero (MERIDIAN): a multicentre, prospective cohort study. Lancet. 14 December 2016. DOI: http://dx.doi.org/10.1016/S0140-6736(16)31723-8