Similar articles

Abstract: A 3D ultrasound thermal model with a 3D finite element representation for modeling the thermal diffusion effects for hepatic ablation induced by spherical-section ultrasound phased array was developed. The model was first validated against available published measured data in rat liver. Using the validated model, effects of blood perfusion and heating schemes on lesion formation were studied for both single focus and split-focus intensity patterns. It was shown that for single focus sonication pattern the short-duration (~2 s) and high-intensity (~1250 W/cm²) heating scheme can completely reduce the cooling effect of the blood perfusion. The lesion shape and size were significantly altered by perfusion for split-focus pattern even with a rapid heating scheme when the focus spacing was larger than 2.4 mm. Underdosed areas might be present between two foci. Prolonging exposure time or shortening focus spacing can reduce the cool region between two foci. In addition, the influences of thermal and acoustic parameters were also studied. When the therapy depth is short (<5 cm), the lesion size monotonically increases with increasing attenuation coefficient that ranges from 5.4 to 11 Np/(m∙MHz).

[1] Chen, L.L., ter Haar, G.R., Hill, C.R., Dworkin, M., Carnochan, P., Young, H., Bensted, J.P.M., 1993. Effect of blood perfusion on the ablation of liver parenchyma with high-intensity focused ultrasound. Phys. Med. Biol., 38(11):1661-1673.

[2] Cheng, K.S., Roemer, R.B., 2005. Blood perfusion and thermal conduction effects in Gaussian beam, minimum time single-pulse thermal therapies. Med. Phys., 32(2):311-317.

[3] Curra, F.P., Mourad, P.D., Khokhlova, V.A., Cleveland, R.O., Crum, L.A., 2000. Numerical simulations of heating patterns and tissue temperature response due to high-intensity focused ultrasound. IEEE Trans. on Ultrason. Ferroelectr. Freq. Control, 47(4):1077-1088.

[4] Ebbini, E.S., Cain, C.A., 1989. Multiple-focused ultrasound phased-array pattern synthesis: optimal driving-signal distributions for hyperthermia. IEEE Trans. on Ultrason. Ferroelectr. Freq. Control, 36(5):540-548.

[5] Fan, X., Hynynen, K., 1992. The effect of wave reflection and refraction at soft tissue interfaces during ultrasound hyperthermia treatments. J. Acoust. Soc. Am., 91(3):1727-1736.

[6] Fan, X., Hynynen, K., 1994. The effects of curved tissue layers on the power deposition patterns of therapeutic ultrasound beams. Med. Phys., 21(1):25-34.

[7] Gertner, M.R., Wilson, B.C., Sherar, M.D., 1997. Ultrasound properties of liver tissue during heating. Ultrasound in Med. & Biol., 23(9):1395-1403.

[8] Graham, S.J., Chen, L., Leitch, M., Peters, R.D., Bronskill, M.J., Foster, F.S., Henkelman, R.M., Plewes, D.B., 1999. Quantifying tissue damage due to focused ultrasound heating observed by MRI. Magn. Reson. Med., 41(2):321-328.

[9] Huang, J.L., Holt, R.G., Cleveland, R.O., Roy, R.A., 2004. Experimental validation of a tractable numerical model for focused ultrasound heating in flow-through tissue phantoms. J. Acoust. Soc. Am., 116(4):2451-2458.

[10] Kolios, M.C., Sherar, M.D., Hunt, J.W., 1996. Blood flow cooling and ultrasonic lesion formation. Med. Phys., 23(7):1287-1298.

[11] Kudo, M., Murakami, T., Hashimoto, K., Hori, M., Kim, T., Nakamura, H., 2004. Comparison of the Hepatic Perfusion Parameters in Patients with Normal and Chronic Liver Disease. 90th Scientific Assembly and Annual Meeting of the RSNA. Chicago.

[12] Li, G.W., 2001. Research of High Intensity Focused Ultrasound Phased Array and Treatment Thermal Field. Ph.D Thesis, Shanghai Jiao Tong University, China (in Chinese).

[13] Li, F., Feng, R., Zhang, Q., Bai, J., Wang, Z., 2006. Estimation of HIFU induced lesions in vitro: numerical simulation and experiment. Ultrasonics, 44(S1):337-340.

[14] Liu, D.L., Saito, M., 1989. A new method for estimating the acoustic attenuation coefficient of tissue from reflected ultrasonic signals. IEEE Trans. on Med. Imaging, 8(1):107-110.

[15] Lu, M., Wan, M., Xu, F., Wang, X., Chang, X., 2006. Design and experiment of 256-element ultrasound phased array for noninvasive focused ultrasound surgery. Ultrasonics, 44(S1):325-330.

[16] Mahoney, K., Fjield, T., McDannold, N., Clement, G., Hynynen, K., 2001. Comparison of modelled and observed in vivo temperature elevations induced by focused ultrasound: implications for treatment planning. Phys. Med. Biol., 46(7):1785-1798.

[17] Meaney, P.M., Clarke, R.L., ter Haar, G.R., Rivens, I.H., 1998. A 3-D finite-element model for computation of temperature profiles and regions of thermal damage during focused ultrasound surgery exposures. Ultrasound in Med. & Biol., 24(9):1489-1499.

[18] Meaney, P.M., Cahill, M.D., ter Haar, G.R., 2000. The intensity-dependence of lesion position shift during focused ultrasound surgery. Ultrasound in Med. & Biol., 26(3):441-450.

[19] Panescu, D., Whayne, J.G., Fleischman, S.D., Mirotznik, M.S., Swanson, D.K., Webster, J.G., 1995. Three-dimensional finite element analysis of current density and temperature distribution during radio-frequency ablation. IEEE Trans. on Biomed. Eng., 42(9):879-890.

[20] Pennes, H.H., 1948. Analysis of tissue and arterial blood temperatures in the resting human forearm. J. Appl. Phys., 1(2):93-122.

[21] Persson, J., Hansen, E., Lidgern, L., McCarthy, I., 2005. Modeling of the heat distribution in the intervertebral disk. Ultrasound in Med. & Biol., 31(5):709-717.

[22] Sapareto, S.A., Dewey, W., 1984. Thermal dose determination in cancer. Int. J. Radiat. Oncol. Biol. Phys., 10(6):787-800.

[23] Sasaki, K., Azuma, T., Kawabata, K.I., Shimoda, M., Kokue, E.I., Umemura, S.I., 2003. Effect of split-focus approach on producing larger coagulation in swine liver. Ultrasound in Med. & Biol., 29(4):591-609.

[24] Valvano, J.W., Cochran, J.R., Diller, K.R., 1985. Thermal conductivity and diffusivity of biomaterials measured with self-heating thermistors. Int. J. Thermophys., 6(3):301-311.

[25] Zderic, V., Keshavarzi, A., Andrew, M.A., Vaezy, S., Martin, R.W., 2004. Attenuation of porcine tissues in vivo after high intensity ultrasound treatment. Ultrasound in Med. & Biol., 30(1):61-66.