New dye-based imaging enables intraoperative aneurysm assessment.
Interim results from an ongoing study include 88 patients with 94 saccular aneurysms, about half of which were ruptured. Researchers compared intra-operative indocyanine green (ICG) video angiography with both intraoperative and postoperative digital subtraction angiography (DSA). ICG image quality was considered excellent in 98% of the images and generally showed good concordance with DSA, said Dr. Andreas Raabe of the department of neurosurgery at Johann Wolfgang Goethe University, Frankfurt am Main, Germany.
Intraoperative DSA can, in some cases, change treatment for patients who have undergone surgical clipping of aneurysms, but surgeons can't predict who will need this imaging technique. "Routine use of intraoperative angiography for unselected cases is unrealistic in most centers," Dr. Raabe said. Also, the technique is invasive and adds to the complication rate.
ICG video angiography during surgery appears to provide an attractive alternative. The ICG dye, which is commonly used in ophthalmology, is given intravenously. The microscope used in the procedure is modified to emit a wave-length of light that excites the dye, which then fluoresces a different wavelength of light that is collected in the microscope. Special filters in the microscope remove the light from other sources. The result is an image of the vessels containing the dye.
Patients in the study ranged in age from 21 to 81 years. Overall, 153 ICG images were made. The time required to perform an angiogram is less than 2 minutes, Dr. Raabe said.
In 36 of 38 cases in which ICG images were compared with post-operative DSA images--and in 36 of 41 cases in which ICG images were compared with intraoperative DSA images--the images were in concordance.
The placement of surgical clips used to treat the aneurysms was corrected for 6 of the 88 patients based on ICG images. No corrections were performed for any of the patients based on DSA results.
The disadvantage of ICG video angiography is that "we can only see the blood flow where we can see the [blood vessel] structure with our eyes," Dr. Raabe said. "The advantage is that this is a very simple and quick method. The surgeon does not have to interrupt his surgical workflow."
But the technique allows immediate correction that might improve the quality of aneurysm surgery, he added.
BY KERRI WACHTER
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|Publication:||Internal Medicine News|
|Date:||Sep 15, 2004|
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