NEW ORLEANS, Feb. 22 -- A team from the Oregon Stroke Center in Portland, Ore., has for the first time used lasers to remove stroke-causing blood clots. At the American Stroke Association's recent international conference, the group discussed preliminary results on five stroke patients treated with an experimental procedure that uses lasers to vaporize clots in the carotid arteries.The study was designed to examine the safety of the technique, which the team said was the first use of laser clot-busting, or thrombolysis, in stroke patients. Scientists emphasized that extensive research will need to be performed before it can be determined whether patients show improvements following laser treatment. It looks very promising, said Wayne M. Clark, leader of the Oregon team. But at this point, we're mainly studying the safety. We have achieved complete vessel re-opening in some patients, while in others, treatment was not possible due to difficulties getting to the clot with the laser-tipped catheter.