Novel laser system and laser irradiation method reduced the risk of carbonization during laser interstitial thermotherapy: assessed by MR temperature measurement.
OBJECTIVE
To establish laser interstitial thermotherapy (LITT) for intracranial tumors, the authors investigated a method to regulate localized temperature generated by interstitial laser irradiation using magnetic resonance (MR) temperature mapping.


METHODS
A diode laser system and six different types of optical-fiber system were developed for LITT. The characteristics of temperature profiles produced by each laser-fiber system were investigated with MR temperature measurement (the water proton chemical technique), and differences in the temperature profile induced by two laser-irradiation methods (continuous and intermittent) were observed.


RESULTS
All fiber systems with the exception of the diffuse-projection fiber system, created a spherical temperature profile. Carbonization sometimes occurred around the bare-end fiber tip upon high power laser irradiation. The diffuse-projection fiber system produced a cylindrical temperature distribution, and the temperature profile showed a more gradual temperature elevation than the bare-end fiber. No carbonization occurred at the tip of the diffuse-projection fiber system. In addition, the utilization of the intermittent irradiation method also increased temperature gradually. Fiber-system modification and intermittent irradiation reduced laser-beam intensity and the risk of carbonization.


CONCLUSIONS
The use of a diffuse-projection fiber system which intermittently transmits a reduced intensity laser beam is an effective tool to regulate temperature during LITT using MR temperature measurement.
Atsumi
H
H
Department of Neurosurgery, Tokai University School of Medicine, Bohseidai, Isehara, Kanagawa 259-1193, Japan. h-atsumi@is.icc.u-tokai.ac.jp
Matsumae
M
M
Kaneda
M
M
Muro
I
I
Mamata
Y
Y
Komiya
T
T
Tsugu
A
A
Tsugane
R
R
D000818:Animals; D001921:Brain / Q000473:pathology; D002645:Chickens; D006979:Hyperthermia, Induced; D007834:Lasers; D008279:Magnetic Resonance Imaging; D018482:Muscle, Skeletal; D011817:Rabbits; D013696:Temperature