Planar strain analysis of liver undergoing microwave thermal ablation using x‐ray CT

摘要: Purpose: To study the planar strain effects in liver during microwave (MW) thermal ablation as a means for tracking tissue expansion and contraction method improving monitoring. Methods: 1.4 mm circular metallic markers were inserted into 16 ex-vivo bovine fresh specimens, that subsequently ablated (with inside specimen) by 40 W of energy, 1, 2, 3, 6, 10 min. The tracked using an x-ray CT scanner. Images acquired every 5–10 s enabling determination markers’ coordinates over time. 2D principal strains calculated triangles formed subgroups three markers, their index, Ω, was plotted vs In addition, radial distance from antenna measured at end each ablation. Subsequently, sliced parallel to imaged planes zone traced digitized. average radius then computed compared distance. Results: strain, Ω(t), profile demonstrated ascending pattern until reaching maximum about 180 s, with mean peak value (Ω = 1.31 ± 0.04) indicating expansion. Thereafter, Ω progressively declined remaining duration treatment, contraction. Furthermore, when plotting size time time, it found two curves intercepted corresponding strain. Conclusions: By detecting point maximal tissues MW application, is possible noninvasively identify location front. fact proximal expands first part treatment contracts front reaches it, may serve index monitoring treatment.