Simultaneous irradiation and imaging of blood vessels during pulsed laser delivery.
OBJECTIVE
Simultaneous irradiation and viewing of 10-120 microm cutaneous blood vessels were performed to investigate the effects of 2-micros 577-nm dye laser pulses.


METHODS
A modified scanning laser confocal microscope recorded vessel response to different radiant exposures (J/cm2). Probit analysis determined the 50% probability ("threshold") radiant exposure necessary to cause embolized or partly occluding coagula, coagula causing complete blood flow stoppage, and hemorrhage.


RESULTS
A statistically significant difference in the threshold radiant exposure existed for each damage category for blood vessels 10-30 microm in diameter, but not for larger vessels. For vessels over 60 microm, complete flow stoppage was unattainable; increasing laser pulse energy produced hemorrhage. In larger vessels, coagula often were attached to the superficial vessel wall while blood flowed underneath. Monte Carlo optical and finite difference thermal modeling confirmed experimental results.


CONCLUSIONS
These results provide insight into the role of pulse duration and vessel diameter in the outcome of pulsed dye laser irradiation.
Barton
J K
JK
Biomedical Engineering Program, University of Arizona, Tucson 85721-0104, USA. barton@u.arizona.edu
Hammer
D X
DX
Pfefer
T J
TJ
Lund
D J
DJ
Stuck
B E
BE
Welch
A J
AJ
D000792:Angiography / Q000379:methods*; D000818:Animals; D001773:Blood Cells / Q000528:radiation effects; D001783:Blood Flow Velocity / Q000528:radiation effects; D001808:Blood Vessels / Q000528:radiation effects*; D006224:Cricetinae; D007834:Lasers; D008647:Mesocricetus; D018613:Microscopy, Confocal; D012235:Rhodamines / Q000008:administration & dosage; D012867:Skin / Q000098:blood supply*
D012235:Rhodamines; C031741:Yellow II