医学考博英语阅读 | 诊断皮肤癌的更好方法

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Science and technology 科学技术

Medical technology 医学技术

Skin deep

肌肤之下

A better way to diagnose skin cancers

诊断皮肤癌的更好方法

DERMATOLOGISTS are good at spotting unusual bits of skin that might or might not be cancers. Testing whether they actually are, though, is quite literally a bloody pain. For a piece of skin to be identified as malignant or benign it must be cut out and sent to a laboratory for examination under a microscope.

皮肤病医学家擅长发现一小块异常皮肤是否有患癌症的可能性。但是，要检查出是否真患癌症的确会让人感到出血之痛。因为要鉴定一块皮肤是恶性还是良性，就必须切下来，然后送到实验室的显微镜下检验。

But a team of researchers led by Rainer Leitgeb, a physicist at the Medical University of Vienna, hope to change that. As they describe in Biomedical Optics Express, Dr Leitgeb and his colleagues are exploring a technique called optical coherence tomography, which they think will allow skin cancer to be diagnosed in situ.

但是，由维也纳医科大学物理学家 Rainer Leitgeb 带领的研究小组希望改变这个现状。正如他们在《生物医学快报》上所描述的那样，Leitgeb 博士和他的同事正在探寻光学相干断层成像术。在他们看来，使用这种技术能在原皮肤上进行皮肤癌诊断。

OCT is a form of optical echolocation. It works by sending infra-red light into tissues and analysing what bounces back. The behaviour of the reflected rays yields information on the structures that they collided with. That, Dr Leitgeb hoped, could be used to generate a map of features just beneath the surface of the skin.

OCT 的原理是光学回声定位，先向身体组织发射红外线，然后再分析反射回来的红外线。Leitgeb 博士希望，这能用来绘制显示皮肤表面下特征的地图。

Similar technology has been employed for nearly two decades by eye doctors and Dr Leitgeb felt that, with a bit of tinkering, it should work for skin as well. The OCT systems operated by ophthalmologists use low-power lasers which produce light with a wavelength of 850 nanometres.

相似的技术应用于眼科已有将近二十年的历史。Leitgeb 博士认为，经过小小的改进，也能用于皮肤科。眼科医生操作的 OCT 系统使用的是低功率激光器，能够发出 850 纳米波长的光线，这刚好超出了眼睛视杆视锥层可感光的范围。

That is just beyond the range detectable by the rods and cones of the eye, and is thus ideal for probing that organ without discomforting the patient. Skin, however, is insufficiently transparent at this wavelength, so one thing Dr Leitgeb had to do was change it.

因此，既能够完成眼睛检查而又不给病人带来不适感，用这种激光再合适不过了。但是，皮肤在这种波长下还不够透明，因此 Leitgeb 博士所要做的就是进行改变。

Another thing which had to change was the speed at which the laser operates. In the ophthalmological system, images are built up from a series of pulses. The more of these the laser sends in, the more light returns to the device and the higher the resolution of the resulting image.

除此之外，还需要改变激光器发射的速度。眼科用的是脉冲成像的方法。激光器发射进去的激光越多，反射出来的光线也就越多，所成像的分辨率也就越高。

However, that image must be built up quickly, otherwise movement of the tissue being illuminated will blur it. For eyes, between 20,000 and 60,000 bursts a second is enough. But to photograph blood vessels inside skin Dr Leitgeb knew more would be needed.

但是，必须迅速建构图像，否则受到照射的组织就会运动，使图像变得模糊不清。用于眼镜检查的脉冲每秒 2 万至 6 万就足够了。但是 Leitgeb 博士知道，要拍到隐藏在皮肤之下的血管，这个数值远远不够。

In the end, he commissioned a group of researchers at Ludwig-Maximilians University in Germany to design an instrument which produces light with a wavelength of 1,300 nanometres and has the ability to fire 440,000 pulses a second.

最后，Leitgeb 博士委托德国慕尼黑大学的一个研究小组设计了能够每秒产生1300 纳米波长、44 万脉冲的激光器。

With their new laser in hand, Dr Leitgeb and his colleagues set up an experiment that let them test the system on a range of skin conditions, including a healthy human palm, allergy-induced eczema on the forearm, inflammation of the forehead, and two previously diagnosed cases of basal-cell carcinoma.

有了新的激光器，Leitgeb 博士和他的同事就开始进行实验，在不同状况的皮肤上测试人的器官系统，包括无任何疾病的手掌，前臂上过敏引起的湿疹皮肤，前额上有炎症的皮肤以及之前诊断过的两例基底细胞癌。

They expected to see normal blood vessels in the healthy palm, increased perfusion caused by dilated and altered vessels in the eczema and the inflammation, and a chaotic jumble of vessels feeding the cancers.

他们期待看到的结果是：无疾病手掌下的血管是正常的；前臂上的湿疹和有炎症的前额下的血管由于扩张和形变造成了灌注量的增加；而为癌细胞供血的血管乱七八糟扭成一团。

And that is exactly what they did see. Moreover, the images of the vessels supplying blood to the tumours were good enough to allow them to calculate blood-flow rates.

他们所看到的结果也正是如此。此外，供血给肿瘤的血管的图像十分清晰，他们还能计算出血流流速。

That, Dr Leitgeb suggests, could also help treatment by allowing doctors to identify the times during their development when tumours are most vulnerable to starvation by having their blood supply cut off.

博士认为，这对治疗也有帮助：医生能通过该方式鉴定肿瘤发展中最易因切断血液供给而饿死的阶段。