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- Möller, Páll H., et al.
(författare)
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Interstitial laser thermotherapy : Comparison between bare fibre and sapphire probe
- 1995
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Ingår i: Lasers in Medical Science. - 0268-8921. ; 10:3, s. 193-200
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Tidskriftsartikel (refereegranskat)abstract
- A sapphire probe and a bare fibre were compared with respect to temperature control and distribution and light fluence in interstitial laser thermotherapy. Experiments were performed in processed liver using an Nd-YAG laser and output power levels of 1-4 W. The temperature was controlled at a distance of 10 mm using a feedback circuit with an automatic thermometry system and thermistor probes. With the sapphire probe, carbonization was rare at power levels of 1-2 W but was observed in half of the experiments at 3 W and in all experiments at 4 W. Using the bare fibre, carbonization was seen in almost all experiments. Absence of carbonization was associated with a moderate decrease in the penetration of light and excellent control of the temperature, whereas carbonization led to rapid impairment of light penetration and temperature control. In addition, the temperature gradient was smaller with the sapphire probe than with the bare fibre or when carbonization was absent. It is concluded that a diffuser tip, such as the sapphire probe, may be preferable to the bare fibre for interstitial laser thermotherapy because it gives a smaller temperature gradient and helps to avoid carbonization which results in preserved light penetration and improved temperature control.
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| 3. |
- Möller, Páll H., et al.
(författare)
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Interstitial laser thermotherapy in pig liver : Effect of inflow occlusion on extent of necrosis and ultrasound image
- 1997
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Ingår i: Hepato-Gastroenterology. - 0172-6390. ; 44:17, s. 1302-1311
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: The aim was to investigate the effect of blood inflow occlusion on lesion size and ultrasonographic findings during interstitial laser thermotherapy of normal liver. Methodology: Pigs were treated with or without hepatic inflow occlusion at a laser power of 3 W or without inflow occlusion at 5 W (target temperature 43°C). The thermotherapy system consisted of an Nd:YAG laser and a temperature feedback circuit. Ultrasonography was performed immediately after treatment. Lesion size was determined using light microscopy including immunohistochemistry with bromodeoxyuridine. Results: Hyperechoic ultrasonographic changes were observed after treatment with inflow occlusion or when there was carbonization. If carbonization did not occur, unoccluded blood flow was associated with hypoechoic lesions. Following inflow occlusion, maximum lesion width 2 and 6 days after thermotherapy averaged 21.9 ± 1.3 and 20.2 ± 0.8 (means ± SEM) mm, respectively. This was larger than the corresponding values of 10.8 ± 0.8 and 11.1 ± 2.0 observed after treatment without inflow occlusion at 3 W (p < 0.01). Increase in laser power from 3 to 5 W in experiments without inflow occlusion produced early carbonization and a slight increase in lesion size that did not match that produced by inflow occlusion. Ultrasound gave a correct prediction of necrosis size after treatment with inflow occlusion but overestimated the necrosis when inflow occlusion was not used. Ultrasound was furthermore unable to predict size of necrosis in individual experiments. Conclusion: Blood flow has a major influence on lesion size in interstitial laser thermotherapy of the liver and affects ultrasonographic images. Also, it appears that intraoperative ultrasonography cannot monitor lesion size with an accuracy that is sufficient for clinical use.
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- Möller, Páll H., et al.
(författare)
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Interstitial laser thermotherapy of adenocarcinoma transplanted into rat liver
- 1997
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Ingår i: European Journal of Surgery. - 1102-4151. ; 163:11, s. 861-870
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To examine the effect of different temperatures and exposure times in interstitial laser thermotherapy. Design: Controlled laboratory study. Setting: University hospital, Sweden. Material: 48 male Wistar FU rats with dimethylhydrazine-induced adenocarcinoma transplanted into the liver. Intervention: Treatment was given with an Nd:YAG laser and a feedback system for temperature regulation. Light was delivered into the centre of the turnout and the feedback thermistor probe was placed 3 mm from the tumour margin. Rats were treated at steady-state temperatures at the feedback thermistor of 43, 46, or 50°C for 30 minutes, and at a steady-state temperature of 46°C at the feedback thermistor also for 10 and 20 minutes. Main outcome measurement: Tumour control as assessed 6 days after treatment using light microscopical examination including immunohistochemical determination of bromodeoxyuridine (BrdU) incorporation into DNA as a measure of cell viability. Results: Complete tumour necrosis was achieved in all rats treated for 30 minutes, in 6/8 rats treated for 10 minutes and in 6/8 rats treated for 20 minutes at 46°C. During steady-state thermotherapy, temperatures at the tumour margin were about 11°higher than at the feedback thermistor (range 54-61°C). The surrounding liver tissue also became necrotic so that the total necrosis volume exceeded the pretreatment tumour volume. Conclusion: Interstitial laser thermotherapy at temperatures ranging from 54-61°C at the tumour margin ensures total necrosis of a transplanted rat liver carcinoma provided that treatment is given for 30 minutes.
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