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Research Papers

# A Study on Mechanical Damage of Tumor Microvasculature Induced by Alternate Cooling and Heating

[+] Author and Article Information
Yuanyuan Shen

School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, P.R.China

Aili Zhang1

School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, 800 Dong Chuan Road, Shanghai 200240, P.R.Chinazhangaili@sjtu.edu.cn

Lisa X. Xu1

Med-X Research Institute and School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, P.R.Chinalisaxu@sjtu.edu.cn

1

Corresponding author.

J. Thermal Sci. Eng. Appl 1(3), 031002 (Dec 03, 2009) (9 pages) doi:10.1115/1.4000582 History: Received April 20, 2009; Revised October 29, 2009; Published December 03, 2009; Online December 03, 2009

## Abstract

Tumor microvascular damage caused by the alternate cooling and heating treatment was found much more severe than that of cooling or heating alone from our previous experimental studies. The induced stresses on the vessel wall are expected to play an important role in vascular damage. Both thermal and mechanical stresses are involved due to the rapid changes in temperature and blood reperfusion during the treatment. To investigate the stress effect, theoretical modeling and numerical simulations have been performed in the present study. Thermal stresses on the tumor microvessel wall during the freezing process are analyzed using the elastic models through the coupled field method. To simulate mechanical stresses induced by blood reperfusion, the fluid and structural mechanics are coupled on the interface between the blood flow domain and the vessel wall. Numerical results show that the thermal stress on the vessel wall is negative in the tumor center, indicating the compression effect during the freezing process. The magnitude of the radial stress reaches $2.5×107 dyn/cm2$. During the postheating process, the nonuniform stress distribution exists in the tortuous periphery vessel wall owing to the irregular structures, and higher stresses normally appear at the vessel bifurcations. Synergy of the thermal and mechanical stresses on the vessel wall play critical roles in damaging of the heterogeneous tumor vasculature during the alternate cooling and heating treatment. Results obtained in the present study are expected to help better understand the vascular injury process, and to develop a more effective thermal treatment protocol for tumor therapy.

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## Figures

Figure 1

Temperature histories of the different thermal treatments: (a) single cooling at −10°C for 1 h; (b) single heating at 42°C for 1 h; and (c) cooling at −10°C for 1/2 h followed by heating at 42°C for 1/2 h

Figure 2

Geometric models used for simulations: (a) the tumor region; (b) the center vessel; and (c) the peripheral vessel

Figure 3

Flow chart for the thermal stress analysis (a) and the blood flow induced vessel wall stress analysis (b)

Figure 4

Comparisons between the numerical results (symbols) and the analytical solutions (lines) for model validation: (a) thermal; and (b) stress

Figure 5

Comparisons between the numerical results (symbols) and the analytical solutions (lines) for the vessel wall stress model validation

Figure 6

Temperature histories of one point selected in the tumor center during the alternate treatment and the single cooling processes, respectively

Figure 7

Histories of the radial, axial, and circumferential stresses on the inner wall of the vessel in the tumor center during the alternate treatment

Figure 8

Equivalent stress histories of the vessel wall in the center and periphery during the alternate and the single cooling treatment processes, respectively

Figure 9

Equivalent stress distribution of tumor vessels in the center (a) and the periphery (b) of a frozen tumor

Figure 10

Wall shear stress distribution on the vessel wall in the center (a) and periphery (b)

Figure 11

The Von Mises stress distribution on the vessel wall in the tumor center (a) and the periphery (b)

Figure 12

Simulated stress history on the vessel wall in the tumor periphery during the heating or the natural thawing processes until hemorrhage occurs (symbols × illustrate the rupture time)

Figure 13

The von Mises stress distribution of the y-branch vessel in the tumor center when the outlet pressure is 11.4 mm Hg (a) and increased to 23.8 mm Hg (b)

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