Ultrasound interstitial applicator for digestive endoscopy: in vivo destruction of bilary tissues

The frequent late diagnosis and the poor efficiency of systemic therapy such as radiotherapy generate huge difficulties in the treatment of ducts cancers. Palliative techniques of bilary debulking, either surgical or by endoscopic route, are actually performed. A light invasive local treatment would allow to fill up this therapeutic gap. Thus, the authors developed an ultrasound applicator for interstitial thermal therapy compatible with classical techniques of digestive endoscopy. The applicator is fitted with a water-cooled plane transducer, operating at 10 MHz, to produce rapid and deep coagulation necroses in a perfused environment. The rotation of the applicator around its axis is necessary to necrose the tissues surrounding the bilary lumen. A flexible metallic shaft (2 m long and 3.8 mm outer diameter), joining the active head with the transducer to the connecting end, enables the remote rotational motion control from the outside of the endoscope. In vivo experiments were conducted on pigs. An abdominal laparotomy was carried out to perform surgically the sphincterotomy of the bilary ducts. Then, the duodenoscope was slid, through the oesophagus, into the duodenum in front of the opened ampulla of Vater. A guide wire was positioned to drive the applicator through the endoscope operating channel into the bilary ducts. Sharp and repetitive coagulation necroses, 8-10 mm in depth, were generated both in the bilary ducts and the liver. These results demonstrated encouraging possibilities for the bilary ducts cancers treatment thanks to the authors' applicator.