翻译：接下来我们看个病例患者男性72岁胆总管下段肿瘤在肝内胆管左外支置入PTCD管我们可以看到常规超声无法显示引流管尖端及其具体走形在经引流管注入造影剂后清晰显示了引流管的走形及其尖端位置。

Next, let's take a look at a case. The patient is a 72-year-old male with a tumor in the lower segment of the common bile duct. A PTCD tube was placed in the left external branch of the intrahepatic bile duct for drainage. We can see that conventional ultrasound cannot display the tip and specific shape of the drainage tube, but after injecting contrast agent through the drainage tube, the shape and the tip position of the drainage tube are clearly displayed.