International Circulation: What are the prospects for imaging technologies such as OCT in CTO intervention? What is the value of these imaging technologies?
　　Dr Katoh: The imaging guidance is very important. I think there is no future for OCT for CTO intervention. I have studied OCT for the CTO procedure for almost ten years in China， Indonesia and Japan. In order to get a better image in OCT， we have to flush the plaque. This is very difficult in CTO. Dr Simpson’s OCT-guided CTO device for the peripheral system is useful because the vessel size is larger and there is a bigger space even in CTO. Originally I believed there was no blood in the occlusion and that there was no need to flush in the periphery， but that is wrong. You have to flush even in occlusion. There is so much blood. It required a very special catheter to flush inside the occlusion. The Tornus catheter was originally developed as a tool to make a hole in the occlusion for the OCT wire. After that， the company wanted to market the device for PCI procedures but originally it was for the OCT. I had to make this catheter capable of flushing. It is a very tiny catheter but the flushed water would come back proximally. The surface of the catheter has a small trough-like indentation through which the water can be flushed and the retrieved proximally. On completion of the development of the catheter system， we performed a clinical study on about twenty cases but the overall procedure is very complex. It requires an automatic flushing system and a pressure safety cut-off when flushing pressures get too high. So we had to stop that project but I learned a lot. Even when we flushed the occlusion with the special catheter， it is very difficult to get a clear image and also penetration is very limited. At the time， penetration was maybe only less than 2mm. That is the limitation in using OCT for CTO recanalization. My opinion is that IVUS is much better than OCT for CTO recanalization. There is a company now working with the new IVUS system using optical fiber. In the near future， we will have a CTO device using optic fiber but it will not be OCT.
　　《国际循环》：OCT等影像学技术在CTO介入中 的应用前景如何？这些影像学技术有何价值？
　　Dr Katoh: 影像学的引导非常重要。但我认为OCT对CTO介入并无应用价值。我已经花了10余年时间，在中国、印度尼西亚和日本研究OCT在CTO术中的应用。为获得较好的OCT图像，我们必须不断冲洗斑块，在CTO病变中这非常困难。Simpson博士报告的用于外周血管的OCT引导的CTO装置非常有帮助，因为外周血管较粗大，即使是CTO病变仍有很大的空间。最初时我认为闭塞病变中没有斑块，不需要进行冲洗，但事实证明这种观点是错误的。你必须进行冲洗，局部存在如此多的斑块，需要使用一种非常特殊的导管在闭塞病变内进行冲洗。最初设计Tornus导管的目的是将Tornus导管作为一种工具为OCT导丝在闭塞处开一个孔。此后，生产商希望将此装置上市用于PCI手术，但其最初是用于OCT的器材。我必须使这种导管能够进行冲洗操作。该导管非常细，冲洗液体可从近端返流回来。导管的表面有一小的凹槽，可通过凹槽冲洗和回收冲洗液体。在完成这种导管系统的改进后，我们在近20例患者中进行了临床研究，但总体上操作非常复杂。它需要一个自动冲洗系统，并且在冲洗压力过高时需要能够安全地关闭。因此我们不得不中止了这一计划，但这个过程的确教给我们很多东西。即使使用特殊导管冲洗闭塞处，仍然难以获得清晰的成像，OCT只能穿透2 mm，这也是CTO再通过程中使用OCT的局限性。我的观点是，在CTO开通术中，IVUS比OCT更好。有一家公司正在研发使用光纤的新型IVUS系统。在不远的将来，我们将拥有使用光纤的CTO装置，但不会是OCT。
　　International Circulation: Will that be imaging during the procedure?
　　Dr Katoh: In the CTO procedure， we don’t need a forward-looking imaging system. When we have a forward-looking system， we can get some image but we don’t know in which direction we are looking. It is a big problem in the forward-looking system. If we don’t know which way we are looking， we can’t control the wire. To control the wire we need fluoroscopy because the imaging system can only provide information from immediately around the catheter. On the fluoroscopy， we are aiming upwards but on a forward-looking system， upward is which way? This is the big limitation in the forward-looking system. For the CTO crossing， we don’t need a forward-looking system but just put in the imaging wire and create a channel and the wire goes into a false channel adjacent to the true lumen. Then we make the channel and put in the imaging wire and get a cross-sectional image.
　　《国际循环》：那将是术中的影像学技术吗？
　　Dr Katoh: 在CTO介入术中，我们不需要一个前向的成像系统。因为对于前向的图像，我们不知道看到的是哪个方向。这是一个很大的问题。如果我们不知道正在看的是哪个方向，就无法控制导丝。由于成像系统只能提供当时导管周围的信息，我们需要荧光屏透视成像以控制导丝。在荧光屏上我们可以有目标地操作，而在前向成像系统中，我们不知为何方向，这是其主要局限性。在开通CTO的过程中，我们不需要一个前向的成像系统，而是需要将导丝显示在图像中，建立一个通道，操作导丝进入真腔附近的假腔内。如此我们可以建立一个通道并将导丝显示在图像中，从而得到一个横断面成像。

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