title: Gel phantom study with high-intensity focused ultrasound: influence of metallic stent containing either air or fluid.
abstract: We aimed to investigate whether a cylindrical structure containing either air or fluid and with or without a metallic stent affects the volume and density of cavitation produced by high-intensity focused ultrasound via a gel phantom study. Sixteen tissue-mimicking phantoms based on a polyacrylamide gel mixed with bovine serum albumin with a cylindrical hole 1 cm in diameter and 7.5 cm in length were divided into four groups of four phantoms with air in the holes (group 1), four phantoms with fluid in the holes (group 2), four phantoms with air-containing metallic stents (group 3) and four phantoms with fluid-containing metallic stents (group 4). A pulsed high-intensity focused ultrasound beam (50% duty cycle, 40-Hz pulse repetition frequency) at 75 W of acoustic power was directed perpendicularly to the longitudinal axis of the hole, with its focus at the posterior wall of the hole. The size of the cavitation on the x-, y-, and z-axes was measured, and the volumes of cavitation and coagulation were calculated using the formula for the volume of an elliptical cone. The density of cavitation was measured in the tissue phantom anterior to the hole with a 1 × 1-cm square region of interest. For statistical analysis, the Kruskal-Wallis test and Mann-Whitney U-test were used. The phantoms with air-containing holes (groups 1 and 3) developed larger and denser cavitations anterior to the focus, without unnecessary coagulation posterior to the focus, compared with the phantoms with fluid-containing holes (groups 2 and 4), regardless of the presence of stents. All of the axes and volumes of the anterior cavitations were significantly larger than those of the posterior cavitations in groups 1 and 3 (all p-values <0.05). The results of this study might be applied to maximize cavitation to enhance drug delivery into tumors.
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Koung Mi
authors.initials: KM
authors.lastname: Kang
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea; Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea. Electronic address: leejy4u@gmail.com.
authors.forename: Jae Young
authors.initials: JY
authors.lastname: Lee
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Haeri
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea; Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Joon Koo
authors.initials: JK
authors.lastname: Han
authors.affiliation: Department of Radiology and the Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea; Institute of Radiation Medicine, Seoul National University Hospital, Seoul, Korea.
authors.forename: Byung-Ihn
authors.initials: BI
authors.lastname: Choi
mesh_terms: D000388:Air; D040761:Biomimetic Materials / Q000737:chemistry* / Q000528:radiation effects*; D005782:Gels / Q000737:chemistry / Q000528:radiation effects; D019220:High-Energy Shock Waves; D057086:High-Intensity Focused Ultrasound Ablation; D008670:Metals / Q000737:chemistry* / Q000528:radiation effects; D019047:Phantoms, Imaging; D011829:Radiation Dosage; D012542:Scattering, Radiation; D012710:Serum Albumin, Bovine / Q000737:chemistry / Q000528:radiation effects; D015607:Stents
chemical_list: D005782:Gels; D008670:Metals; D012710:Serum Albumin, Bovine
keywords: Air; Cavitation; Fluid; High-intensity focused ultrasound; Pancreatic neoplasms; Phantom study; Stent