Reusable ultrasonic tissue mimicking hydrogels containing nonionic surface-active agents for visualizing thermal lesions.
The present study aims to identify a new recipe for reusable tissue mimicking phantoms that allows the optical visualization of thermal lesions produced in various applications of therapeutic ultrasound where thermal mechanisms are important. The phantom was made of polyacrylamide hydrogel containing a nonionic surface-active agent (NiSAA) as a temperature-sensitive indicator. Threshold temperature above which a thermal lesion is regarded to be formed in the phantom is controlled by selecting an NiSAA. In the present study, three NiSAAs of polyoxyethylene alkyl ether series with nominal clouding points of 66 ( degrees )C, 70 ( degrees )C, and 80 ( degrees ) C were chosen. Test phantoms were prepared with polyacrylamide hydrogel, corn syrup and NiSAAs [5% (w/v)]. Key acoustic properties of the three NiSAA hydrogels were found to be similar to those of human liver. The phantoms were optically transparent at room temperature (25 ( degrees ) C) and became opaque after exceeding the clouding points. The transparency was recovered on cooling, although the system demonstrated hysteresis. The phantoms were tested both in their ability to provide visualization of thermal lesions produced by high-intensity focused ultrasound and also to examine any characteristic differences in the shape of the lesions formed at different threshold temperatures. The present study suggests that the NiSAA polyacrylamide hydrogel will be of a practical use in quality assurance in various applications of therapeutic ultrasound where thermal mechanisms are important.
Park
Seong Keun
SK
Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul 110-744, Korea. seongkeun.park@hotmail.com
Guntur
S R Anjaneya Reddy
SR
Lee
Kang Il
KI
Paeng
Dong-Guk
DG
Choi
Min Joo
MJ
D000180:Acrylic Resins / Q000737:chemistry; D017743:Equipment Reuse; D057086:High-Intensity Focused Ultrasound Ablation / Q000379:methods*; D006801:Humans; D020100:Hydrogels / Q000737:chemistry*; D008099:Liver / Q000000981:diagnostic imaging; D009994:Osmolar Concentration; D019047:Phantoms, Imaging; D013501:Surface-Active Agents / Q000737:chemistry*; D013696:Temperature; D014463:Ultrasonography
D000180:Acrylic Resins; D020100:Hydrogels; D013501:Surface-Active Agents; C016680:polyacrylamide gels