A polyacrylamide gel phantom for radiofrequency ablation

Abstract

A polyacrylamide gel (PAG) containing bovine serum albumin (BSA) is introduced as a new tissue-mimicking phantom for the purpose of visualizing three-dimensional coagulation temperature distribution during radiofrequency ablation (RFA). The coagulation temperature of the phantom can be changed at the same range of biological tissue (50-60 degrees C) by adjusting the pH from 4.3 to 4.7. The phantom is transparent except in thermal coagulation regions which are ivory white. The physical properties of the phantom, such as density, electrical conductivity and specific heat capacity, are very favorable, similar to those of soft tissues. We illustrate the usefulness of the phantom in visualizing RFA lesions. This phantom has magnetic resonance properties which change drastically upon thermal coagulation, enabling its use for the characterization of RFA device, quality assurance, treatment planning and treatment verification. The PAG containing BSA, whose pH was adjusted from 4.3 to 4.7, is an attractive tissue-mimicking phantom suitable for RFA investigations.

Design of an Optically Controlled MR-Compatible Active Needle

“…For these reasons, polyacrylamide gel (PAG) is adopted, which has been used for radio frequency ablation research. According to [31], PAG can resist temperatures up to 100 °C and is optically transparent or translucent even with additional proteins for visualizing the heated area. Davidson and Sherar [29] measured the thermal properties of PAG, compared with human liver tissue properties [30], summarized in Table III.…”

Image-based 3D modeling and validation of radiofrequency interstitial tumor ablation using a tissue-mimicking breast phantom

“…Table 1 shows the recipe for 1 L of phantom gel with a citrate buffer at a concentration of 0.2 M and pH of 4.3. The gel properties at this pH are reported to mimic human soft-tissue properties with a coagulation temperature of 50 • C (gel turns opaque), although the coagulation temperature of the gel can be adjusted in the range 50-60 • C by changing its pH with the addition of the citrate buffer [13]. A plastic breast mold of 400 mL was used to cast the gel breast phantom, and a small irregular-shaped portion of fresh baby potato (maximal dimension of 25 mm) was embedded inside the phantom to simulate cancerous tissue.…”

“…The mixture was subsequently polymerized using a reaction initiator-activator pair [13]. Table 1 shows the recipe for 1 L of phantom gel with a citrate buffer at a concentration of 0.2 M and pH of 4.3.…”

“…As patient data and images were not available for the study, we used a tissue-mimicking gel [13] that was made in-house for the RFA study. MR images of a gel breast phantom were obtained and used to reconstruct an anatomical 3D CAD model for the proposed study.…”

Radio Frequency Heating of Implanted Tissue Engineered Scaffolds: Simulation and Experimental Studies

“…The phantom has several merits such as stability in high temperatures (50-100°C), solid form to avoid convection heat transfer during thermal treatments, high transparency in room temperature, chemically and physically long time stability, three-dimensional visualization of heating area due to BSA coagulation, easy preparation, and similar thermal and electrical properties as human tissues (Mcdonal et al, 2004;Bu-Lin et al, 2008). BSA (1.5% w/v) (Sigma-Aldrich) was dissolved in 0.02 M citrate buffer consisting of citric acid monohydrous (0.154% w/v) and citrate tribasic dehydrate (0.373% w/v).…”