High-intensity focused ultrasound liver destruction through the gastric wall under endoscopic ultrasound control: first experience in living pigs

Abstract

High-intensity focused ultrasound liver destruction through the gastric wall under endoscopic ultrasound control: first experience in living pigs High-intensity focused ultrasound (HIFU) was first developed to ablate prostatic tissue [1]. The ultrasound beam is focused at the focal point of the transducer and the energy concentration produces tissue necrosis [2]. HIFU has also been used to ablate metastases on the surface of the liver either surgically or via the transcutaneous approach [3,4]. However, beam reflection on gastric gas has produced necrosis of the interposed abdominal wall [5]. An endoscopic device is potentially valuable in treating tumors localized near to the gastric lumen without the difficulties of gas interposition. We developed an endoscopic ultrasound (EUS) HIFU device. We report the first experience of the use of HIFU to treat lesions completely endoscopically under EUS control. We designed a miniaturized HIFU transducer with a 40-mm focal point, a working frequency of 3.8 MHz, and an acoustic power of 35 W. We adapted it to fit onto an Olympus linear echoendoscope (• " Fig. 1). To test this new device, a living pig model was chosen because of its similarity to the human digestive anatomy. The procedure was performed in two pigs that had been given general anesthetics. In each pig, the stomach was initially filled with degassed water. The prototype was then placed on a guide wire in the gastric lumen and focused onto the left lobe of the liver under EUS control (• " Fig. 2). We applied 10 consecutive shots each of 10 seconds and with an effective acoustic power of 35 W. This was repeated five times moving the scope 2 cm between each group of shots. No bleeding or other complications occurred during the procedures. The pigs were sacrificed immediately after the procedures. Examination showed that we had achieved complete necrosis of the liver at the five sites with lesions in the liver 10 mm in length and 8 mm in depth (• " Fig. 3). Only one of the five sites showed evidence of gastric mucosal erythema with whitening of the external gastric wall but with no evidence of perforation or muscle wall damage. The target zone appeared hypoechoic on the EUS endoscopy. We report for the first time the ability to make HIFU lesions on the liver with a completely endoscopic procedure under EUS control with no immediate adverse effects. Other possible targets that could be treated in this way include pancreatic tumors or nodes. This work was supported by a grant from the Agence Nationale de la Recherche (ANR) through the Programme Blanc 2008. Endoscopy_UCTN_Code_TTT_1AS_2AGCompeting interests: None UCTN -Unusual cases and technical notes E376Pioche M et al. HIFU liver destruction through the gastric wall under EUS control … Endoscopy 2012; 44: E376-E377

Integration of deployable fluid lenses and reflectors with endoluminal therapeutic ultrasound applicators: Preliminary investigations of enhanced penetration depth and focal gain

“…The performance in “liver” and “pancreas” can also be generalized as possible in other similar target tissues. Some comparisons can be drawn between the simulations of the proposed applicator assemblies and experimental evaluations of ultrasound applicators developed for endoluminal ablation of liver or pancreatic tissue, as described in literature . Collectively, these applicators had ~12 mm profiles, were placed in the stomach in in vivo porcine studies, and could create thermal lesions of ~1–2 cm maximum penetration into the target liver/pancreatic tissue .…”

Catheter-based ultrasound technology for image-guided thermal therapy: Current technology and applications

“…Simulation and preliminary studies have been reported for phased array devices for such applicators [67-72]. Some of these designs also have integrated MR imaging coils [60, 61] or ultrasound imaging probes [62, 63]. …”

“…A 4-patient pilot study is reported for the ablation of tumors in the esophagus with a transesophageal applicator and feasibility of creating highly-demarcated ablative lesions in the esophagus was indicated [59]. Liver ablation using transgastric ultrasound was also demonstrated in vivo in swine models using an endoscopic device, and it was possible to create small lesions in the liver [58, 62]. Intraductal ablation of tumors in the digestive tract and billiary duct has been studied in swine models where small diameter devices (3.8 – 4 mm) have been deployed within working channels of endoscopes [84, 85].…”

“…Some recent efforts have combined electromagnetic tracking with US imaging to co-register applicator position with anatomy for potential robotic placement [106, 109]. Ultrasound guided endoscopic ultrasound ablation procedures have been reported for clinical esophageal tumor ablation [59] and in liver ablation studies [62]. Similar technology development was conducted for transesophageal cardiac ablation with an imaging transducer centered and integrated within the therapy array for US-guided target localization [63, 86].…”

Endoscopic high-intensity focused US: technical aspects and studies in an in vivo porcine model (with video)

“…It has been long acknowledged that an endoscopic device that would integrate a HIFU transducer and an endoscopic ultrasound (EUS) imaging probe would be a safer and more efficient alternative to extracorporeal HIFU in the ablation of peri-luminal lesions 1,15 . Such an EUS-guided HIFU device would bring many potential benefits including improved targeting, decreased energy requirements, and decreased potential for injury to intervening structures.…”