Brain ablation in the rat cerebral cortex using a tunable-free electron laser.
OBJECTIVE
We used the MARK III free electron laser (FEL) tuned to molecular vibrational absorbance maxima in the infrared (IR) wavelength range of 3.0-6.45 microm to study the effect of these various wavelengths and a power level of 5 mJ/2 microseconds macropulse on photoablation of CNS tissue.


METHODS
Laser lesions were produced in the parietal cortex of anesthetized rats using thermal confined mid-IR (infrared) laser pulses tuned to the -OH, -CH, amide 1, and amide 2 absorbance bands. Histological assessments following recovery periods of 4 hours, 4 days, and 3 weeks were performed to determine the size, shape, and character of the photoablative lesions. Cell density studies were done in adjacent edematous tissue.


RESULTS
Significant differences in lesion size and shape were observed as a function of wavelength. Although maximum ablation and collateral damage seemed to coincide with spectral peaks in the mid-IR, area and depth/width ratios did not.


CONCLUSIONS
It was found in these experiments that wavelengths in the mid-IR could be selected for optimal ablative properties. Using tunable, high-peak-power pulsed lasers, it will be possible to produce well-defined photoablative lesions that conform to small, irregularly shaped neurosurgical targets.
Ovelmen-Levitt
Janice
J
Department of Surgery, Division of Neurosurgery, Duke University Medical Center, Durham, North Carolina 27710, USA.
Straub
Karl D
KD
Hauger
Suzanne
S
Szarmes
Eric
E
Madey
John
J
Pearlstein
Robert D
RD
Nashold
Blaine S
BS
D000818:Animals; D001929:Brain Edema / Q000209:etiology; D002540:Cerebral Cortex / Q000293:injuries* / Q000503:physiopathology / Q000528:radiation effects*; D007259:Infrared Rays / Q000009:adverse effects*; D020300:Intracranial Hemorrhages / Q000209:etiology; D053685:Laser Therapy / Q000009:adverse effects / Q000295:instrumentation; D019635:Neurosurgical Procedures / Q000009:adverse effects*; D010789:Phototherapy / Q000009:adverse effects* / Q000295:instrumentation; D051381:Rats