BBC医学新闻 | MRI 可定位胎儿脑部缺陷
摘要： 胎儿脑部缺陷是指在妊娠期间胎儿大脑发育异常，可能导致流产、死产或出生后严重神经功能障碍。研究表明，在常规超声检查基础上增加胎儿MRI扫描可显著提高诊断准确性，从68%提升至93%。
- 常规20周超声检查可初步筛查胎儿脑部异常，但准确率有限（约68%）。
- 结合胎儿MRI可将诊断准确率提升至93%，尤其在超声结果不确定的“临界病例”中价值显著。
- 研究建议对超声提示可疑脑部异常的孕妇常规提供胎儿MRI检查。
- 95%的孕妇认为胎儿MRI有帮助，并愿意在必要时再次接受该检查。
- 更准确的诊断使终止妊娠的比例从25%上升至36%，反映出信息充分对家庭决策的重要性。
小白老师说：Detailed MRI scans should be offered to some women in pregnancy to help spot brain defects in the developing baby, say researchers.
Extra baby scan ‘spots brain problems’
Ultrasounds are already used to look inside the womb and check that the baby is growing properly.
However, the study on 570 women published in the Lancet showed doctors were able to make a much better diagnosis using MRI scans.
Experts called for the scans to become routine practice.
Pregnant women are offered an ultrasound scan at about 20 weeks that can spot abnormalities in the brain.
They are detected in three in every 1,000 pregnancies.
An MRI scan of a foetus 27 weeks into the pregnancy
If the brain fails to develop properly it can result in miscarriage or still birth. Couples are generally offered counselling and some choose to have an abortion.
More certainty
The study, carried out across 16 centres in the UK, analysed the impact of using MRI scans - which use magnetic fields and radio waves to image the body - to confirm any diagnoses.
Overall, it showed ultrasound gave the correct diagnosis 68% of the time.
But combining that with MRI increased the accuracy to 93%.
The detailed picture of the developing baby’s brain revealed by MRI
The extra tests were most useful in borderline cases where doctors were uncertain of the outcome.
The number of pregnant women who were given an “unknown” diagnosis was more than halved by the extra scans, increasing the confidence that the developing baby’s brain was healthy or not.
Prof Paul Griffiths, from the University of Sheffield, said: “Based on our findings, we propose that an MRI scan should be given in any pregnancy where the foetus may have a suspect brain abnormality.”
About 95% of mothers-to-be said the scan was helpful and would have it again if there were concerns on the ultrasound.
The number of abortions increased from 25% with just the ultrasound to make the decision to 36% with the extra scan.
Dr Cara Mooney, one of the researchers at the University of Sheffield, told the BBC News website: “There may be some people who think it’s controversial, but this is really about informing pregnant women and their families to ensure they have the correct information when they’re going through what can be a traumatic time.”
Commenting on the findings, Prof Rod Scott, from the University of Vermont, said: "Accurate diagnosis of significant brain abnormalities has important implications.
“This trial strongly supports the view that in utero MRI is an excellent technique and it should be incorporated into clinical practice as soon as possible.”
By James Gallagher
Health and science reporter, BBC News website
15 December 2016
常见问题
胎儿MRI比超声更准确吗？
是的。研究显示，超声单独诊断胎儿脑部异常的准确率为68%，而联合胎儿MRI后准确率提升至93%。
哪些孕妇应该做胎儿MRI？
研究建议，当20周超声检查发现胎儿可能存在脑部异常时，应进行胎儿MRI以确认诊断。
胎儿MRI安全吗？
胎儿MRI使用磁场和无线电波，不涉及电离辐射，目前被认为是安全的，且95%的孕妇反馈体验良好。
为什么更准确的诊断会导致更多终止妊娠？
因为MRI提供了更明确的信息，帮助家庭在充分知情的情况下做出符合自身价值观的决定，包括选择终止妊娠。
参考资料
Lancet研究：胎儿MRI提升脑部异常诊断准确性
该研究发表于《柳叶刀》，纳入英国16个中心共570名孕妇。
BBC News: Extra baby scan 'spots brain problems'
↗原始报道由BBC健康与科学记者James Gallagher于2016年12月15日发布。