Unborn twins's different lives
They might share the same DNA and cramped living space, but as these images reveal, life is anything but identical for unborn twins.这对蜷缩在子宫里的孪生宝宝或许享有同一套基因，而上面的画面显示，孪生宝宝即使尚未出生，就已经各自过着截然不同的生活。
This unprecedented glimpse into their inner world is afforded through a recently developed form of magnetic resonance imaging (MRI), which is being turned on twins for the first time.
通过近年发展成熟的磁共振成像（MRI,Magnetic Resonance Imaging）可以清晰瞥见孪生宝宝在母体内的活动情况。这种在胎儿身上的应用，可以说是一次首创。
Whereas conventional MRI takes snapshots of thin slices of the body as it penetrates through it, so-called cinematic-MRI takes repeated images of the same slice, then stitches them together to create a video. This means that a moving structure such as a fetus – or several fetuses – can be visualised in unprecedented detail.
然而传统的MRI图像画面是单张人体切片，而这个动态的MRI录像则是通过对单个固定切面进行连续多次成像，整合汇集成一个动态的录像。这意味着子宫里的胎儿（一个或多个）都能通过这个动态记录获知其宫内活动情况，而且是十分详细的。
"A lot of the so-called videos in the womb are very processed, so they do a lot of reconstructing and computer work afterwards. These are the raw images that are acquired immediately, " says Marisa Taylor-Clarke of the Robert Steiner MR Unit at Imperial College London, who recorded the images.
“大多声称是拍摄宫内胎儿活动的录像都是经过处理的，即图像需经大量的后期重组和计算工作才整合成录像形式。”来自伦敦帝国学院的罗伯特·施泰纳核磁共振影象部门的玛丽莎·泰勒·克拉克表示：“这些原始图像都必须现场截取。”
She has been using the technique to study twin-to-twin transfusion syndrome, a relatively common complication in which the blood supplies of twins sharing the same placenta become connected. As the twin receiving its sibling's blood grows larger, the growth of the donor twin becomes stunted. In the worst cases it can prove fatal to both twins. Fortunately, an operation that involves blocking the shared blood vessels usually saves them, but its impact on brain development is relatively unknown.
利用这种技术可以研究双胞胎输血综合征，这是双胎妊娠中一种比较常见而严重的并发症，双胞胎因共享同一个胎盘，血液供应之间会有交联。接受血液的一方会长得大一点，供给血液的另一方的生长则受阻滞。最糟糕的情形就是这种综合征能导致两个生命的死亡。幸运的是，实施手术阻滞共通血管，通常能救活胎儿，但这种手术会否对脑部发育造成影响则是未知的。
Different brain sizes
脑部大小不一
Taylor-Clarke is using cine-MRI to explore this process in more detail. "Using this technique we can begin to say something about the impact of these two separate environments within a shared environment and how this affects the supposedly genetically identical brain, " she says.
泰勒·克拉克正在应用动态影像MRI详细探讨这种未知的影响。克拉克表示，“通过这项技术，我们逐渐明晰，在同一母体子宫环境下，这两个胎儿所处相对独立环境里产生的各种作用，以及了解这种作用是如何影响理应拥有相同遗传的脑部的。”
Although they have only scanned 24 pairs of twins so far, they are already getting new insights that could help predict future developmental problems. For example, some twins who had undergone the operation and had apparently normal brains when screened using ultrasound showed differences in brain volume when screened using the more sensitive MRI technique.
尽管迄今为止，尽管只有24对胎儿（12位准母亲）参与研究进行扫描，但研究人员表示他们对预测诸如胎儿未来发育问题有了新的认识。比如，对于一些应用超声检查胎儿，显示他们脑部体积相差无几，而应用更灵敏的MRI技术检查时，会发现他们的脑部体积甚至存在较大的差异。
"These donor twins had smaller brains than their co-twins, " says Taylor-Clarke. What's more, those twins with near-identical brain volumes in the uterus seem to do better in terms of their neurodevelopment once they are born than those with a larger difference in brain size.
“比起接受血液的兄弟姐妹，这些供给血液的胎儿，其脑部体积小一点，”泰勒·克拉克表示。再者，相比脑部体积差异较大的孪生胎儿，子宫里脑部体相近的胎儿在出生后有更为完善的神经系统发育。
Ultimately the team hopes to develop a tool that could accurately predict developmental problems in advance of birth, meaning parents could be given extra support once the twins are born.
最后，该研究团队希望研发出这么一项技术：精确预测胎儿出生前的发育问题，这日后或许也意味着准父母们在孩子出生后能拥有额外的技术支持。
But this kind of imaging also holds more general lessons for twin development. Although one might assume that identical twins share the same environment until birth, it's clear that they may have had quite different experiences, which may already have left lasting impressions on their development.
然而这种成像技术检查对胎儿的发育亦存在较为普遍的不良问题。尽管有人会提出，同卵双胞胎在子宫内一直到出生前都共用相同环境，但显而易见的是，胎儿们在子宫里的生命体验是大有差异的，而这种差异可能对胎儿的发育已经留下了终身的影响。
Imperial College London is currently recruiting pregnant women who are carrying twins for further imaging studies. If you are interested in being scanned, contact m.taylor-clarke@imperial.ac.uk
伦敦帝国学院为进一步研究影像，目前正招募怀有双胞胎的孕妇。如果您有兴趣参与研究，请联系与m.taylor-clarke@imperial.ac.
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