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Evaluation of side effects of radiofrequency capacitive hyperthermia with magnetite on the blood vessel walls of tumor metastatic lesion surrounding the abdominal large vessels: an agar phantom study.

Kawai N, Kobayashi D, Yasui T, Umemoto Y, Mizuno K, Okada A, Tozawa K, Kobayashi T, Kohri K - (2014)

Bottom Line: The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow.The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow.Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.

ABSTRACT

Background: Magnetite used in an 8-MHz radiofrequency (RF) capacitive heating device can increase the temperature of a specific site up to 45°C. When treating a metastatic lesion around large abdominal vessels via hyperthermia with magnetite, heating-induced adverse effects on these vessels need to be considered. Therefore, this study examined hyperthermia-induced damage to blood vessel walls in vitro.

Methods: A large agar phantom with a circulatory system consisting of a swine artery and vein connected to a peristaltic pump was prepared. The blood vessels were placed on the magnetite-containing agar piece. Heating was continued for 30 min at 45°C. After heating, a histological study for injury to the blood vessels was performed.

Results: The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow. In the heated vessels, vascular wall collagen degenerated and smooth muscle cells were narrowed; however, no serious changes were noted in the vascular endothelial cells or vascular wall elastic fibers. The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow.

Conclusions: Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels.

No MeSH data available.


Related in: MedlinePlus

Heating. (A) Explanation of RF-8. a–g: same as Figure 1. h: peristaltic pump, i: silicon tube for inflow, j: silicon tube for outflow, k: saline. (B) Thermography. b’: Temperature display of the cylindrical magnetite piece, approximately 45°C. c’: Temperature display of the control piece, approximately 30°C. g’: Temperature display of the water cooler pad, approximately 8°C. j’: Temperature display of the silicon tube for outflow, approximately 35°C. i’: Temperature display of the silicon tube for inflow, approximately 20°C. (C) Time course of temperature changes in b and c. b: The temperature reached 45°C at 27 min after the initiation of heating and remained at this temperature thereafter. c: The temperature reached 35°C at 23 min and did not exceed 37°C thereafter.
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Figure 2: Heating. (A) Explanation of RF-8. a–g: same as Figure 1. h: peristaltic pump, i: silicon tube for inflow, j: silicon tube for outflow, k: saline. (B) Thermography. b’: Temperature display of the cylindrical magnetite piece, approximately 45°C. c’: Temperature display of the control piece, approximately 30°C. g’: Temperature display of the water cooler pad, approximately 8°C. j’: Temperature display of the silicon tube for outflow, approximately 35°C. i’: Temperature display of the silicon tube for inflow, approximately 20°C. (C) Time course of temperature changes in b and c. b: The temperature reached 45°C at 27 min after the initiation of heating and remained at this temperature thereafter. c: The temperature reached 35°C at 23 min and did not exceed 37°C thereafter.

Mentions: Figure 2 shows the schema for heating of the agar phantom and blood vessel using RF-8. The container shown in (k) of Figure 2A contained physiological saline, and saline was pumped up through the silicon tube (i) connected to the peristaltic pump (h). Saline flowed into the blood vessel (e), passing through the agar phantom (a), and discharged into the silicon tube (j). Probes measured the temperature of the region directly adjoining the blood vessel (b) and the control piece (c). Figure 2B shows temperature measurements observed during heating using thermography (Thermography R300; NEC/Avio Co., Ltd., Tokyo). As shown by the scale on the right, red and blue colors represent 45°C and 8°C, respectively. Since 5°C cooling water was circulated in the water pad while heating, thermography displayed the color blue representing a low temperature. The color red, representing 45°C, is displayed beside the blood vessel (b’) in contact with the cylindrical magnetite piece in the agar phantom, whereas the color green, representing ~30°C, is observed for the control piece (c’). The inflow silicon tube (i) was colored blue-green (i’), showing that the inflow saline temperature was approximately 25°C. The outflow silicon tube (j), into which saline flowing out of the blood vessel passed, was colored yellow (j’), showing that the outflowing saline was heated to ~35°C. Figure 2C shows the time-course temperatures in the blood vessel (b) and control piece (c) from the point of initiation of heating using RF-8. In the blood vessel, the temperature reached 45°C at 28 min after heating initiation, while in the control piece, the temperature reached 37°C after 37 min, but no further increase in temperature was observed. Heating was continued for 30 min after the temperature reached 45°C in the blood vessel and for 30 min after it reached 37°C in the control piece.


Evaluation of side effects of radiofrequency capacitive hyperthermia with magnetite on the blood vessel walls of tumor metastatic lesion surrounding the abdominal large vessels: an agar phantom study.

Kawai N, Kobayashi D, Yasui T, Umemoto Y, Mizuno K, Okada A, Tozawa K, Kobayashi T, Kohri K - (2014)

Heating. (A) Explanation of RF-8. a–g: same as Figure 1. h: peristaltic pump, i: silicon tube for inflow, j: silicon tube for outflow, k: saline. (B) Thermography. b’: Temperature display of the cylindrical magnetite piece, approximately 45°C. c’: Temperature display of the control piece, approximately 30°C. g’: Temperature display of the water cooler pad, approximately 8°C. j’: Temperature display of the silicon tube for outflow, approximately 35°C. i’: Temperature display of the silicon tube for inflow, approximately 20°C. (C) Time course of temperature changes in b and c. b: The temperature reached 45°C at 27 min after the initiation of heating and remained at this temperature thereafter. c: The temperature reached 35°C at 23 min and did not exceed 37°C thereafter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
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Figure 2: Heating. (A) Explanation of RF-8. a–g: same as Figure 1. h: peristaltic pump, i: silicon tube for inflow, j: silicon tube for outflow, k: saline. (B) Thermography. b’: Temperature display of the cylindrical magnetite piece, approximately 45°C. c’: Temperature display of the control piece, approximately 30°C. g’: Temperature display of the water cooler pad, approximately 8°C. j’: Temperature display of the silicon tube for outflow, approximately 35°C. i’: Temperature display of the silicon tube for inflow, approximately 20°C. (C) Time course of temperature changes in b and c. b: The temperature reached 45°C at 27 min after the initiation of heating and remained at this temperature thereafter. c: The temperature reached 35°C at 23 min and did not exceed 37°C thereafter.
Mentions: Figure 2 shows the schema for heating of the agar phantom and blood vessel using RF-8. The container shown in (k) of Figure 2A contained physiological saline, and saline was pumped up through the silicon tube (i) connected to the peristaltic pump (h). Saline flowed into the blood vessel (e), passing through the agar phantom (a), and discharged into the silicon tube (j). Probes measured the temperature of the region directly adjoining the blood vessel (b) and the control piece (c). Figure 2B shows temperature measurements observed during heating using thermography (Thermography R300; NEC/Avio Co., Ltd., Tokyo). As shown by the scale on the right, red and blue colors represent 45°C and 8°C, respectively. Since 5°C cooling water was circulated in the water pad while heating, thermography displayed the color blue representing a low temperature. The color red, representing 45°C, is displayed beside the blood vessel (b’) in contact with the cylindrical magnetite piece in the agar phantom, whereas the color green, representing ~30°C, is observed for the control piece (c’). The inflow silicon tube (i) was colored blue-green (i’), showing that the inflow saline temperature was approximately 25°C. The outflow silicon tube (j), into which saline flowing out of the blood vessel passed, was colored yellow (j’), showing that the outflowing saline was heated to ~35°C. Figure 2C shows the time-course temperatures in the blood vessel (b) and control piece (c) from the point of initiation of heating using RF-8. In the blood vessel, the temperature reached 45°C at 28 min after heating initiation, while in the control piece, the temperature reached 37°C after 37 min, but no further increase in temperature was observed. Heating was continued for 30 min after the temperature reached 45°C in the blood vessel and for 30 min after it reached 37°C in the control piece.

Bottom Line: The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow.The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow.Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Nephro-urology, Nagoya City University Graduate School of Medical Sciences, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467-8601, Japan.

ABSTRACT

Background: Magnetite used in an 8-MHz radiofrequency (RF) capacitive heating device can increase the temperature of a specific site up to 45°C. When treating a metastatic lesion around large abdominal vessels via hyperthermia with magnetite, heating-induced adverse effects on these vessels need to be considered. Therefore, this study examined hyperthermia-induced damage to blood vessel walls in vitro.

Methods: A large agar phantom with a circulatory system consisting of a swine artery and vein connected to a peristaltic pump was prepared. The blood vessels were placed on the magnetite-containing agar piece. Heating was continued for 30 min at 45°C. After heating, a histological study for injury to the blood vessels was performed.

Results: The inner membrane temperature did not reach 45°C due to the cooling effect of the blood flow. In the heated vessels, vascular wall collagen degenerated and smooth muscle cells were narrowed; however, no serious changes were noted in the vascular endothelial cells or vascular wall elastic fibers. The heated vessel wall was not severely damaged; this was attributed to cooling by the blood flow.

Conclusions: Our findings indicate that RF capacitive heating therapy with magnetite may be used for metastatic lesions without injuring the surrounding large abdominal vessels.

No MeSH data available.


Related in: MedlinePlus