Gut Liver.  2014 Jul;8(4):433-437.

Factors Affecting Tumor Ablation during High Intensity Focused Ultrasound Treatment

• Hassanuddin A
• Choi JH
• Seo DW
• Ryu CH
• Kim SH
• Park DH
• Lee SS
• Lee SK
• Kim MH

Abstract

BACKGROUND/AIMS
High intensity focused ultrasound (HIFU) utilizes a targeted extracorporeal focused ultrasound beam to ablate neoplastic pancreatic tissue. We used an in vitro model to examine the effects of bone, metallic stents, plastic stents, metal plates, and cyst-like lesions on HIFU treatment.
METHODS
HIFU was delivered to the phantom models implanted with foreign bodies, and the location, shape, and size of the ablated zones were evaluated.
RESULTS
Bone and metallic plates reflected the ultrasound beam, shifting the ablation zone from the focal zone to the prefocal area. In the phantoms containing metal stent, plastic stent, and cyst, most of the ablative energy was reflected to the prefocal area by the surface, with the remainder penetrating through the phantom. The area of the ablated margins was significantly larger in size and volume than the intended focal ablation zone.
CONCLUSIONS
During HIFU therapy, artificial or anatomical barriers could affect the direction of the ultrasound beams, shifting the ablation zone from the focal area to a prefocal site with a larger than expected ablation zone. These factors should be considered prior to HIFU treatment for pancreatic tumors because they could limit ablation success, in addition to causing complications.

Keyword

High-intensity focused ultrasound ablation; Cysts; Metal stent; Phantom

MeSH Terms

Adenocarcinoma/*therapy
High-Intensity Focused Ultrasound Ablation/*methods
Humans
Models, Anatomic
Pancreatic Neoplasms/*therapy
Phantoms, Imaging
Stents