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(Continued from page 129)
flow was associated with an increase in the microemboli seen with the bubble oxygenator. Pugsley demonstrated that in-line arterial filters were also associated with a marked reduction in microemboli during CPB. Plark studied 128 patients undergoing CPB for coronary artery bypass grafting. Although only 41 of these patients underwent neuropsychological testing, they found that >60 microemboli during the procedure was associated with decrements in neuropsychological function.
See slides for references
DIFFERENTIATION BETWEEN NORMAL AND TUMOR BRAIN TISSUE USING SPECTROSCOPY
Original work
During the neurosurgical operation it is often difficult to differentiate between normal brain and certain tumor margins. Some tumors contain capsules; some are different in consistency while others may be markedly different in color. Then there is a group of neoplasms such as gliomas and metastases, which may only differ slightly in appearance. Although a complete surgical resection would improve the survival and quality of life, in the areas of significant brain function it would not be prudent to resect large margins to reduce the log kill of the tumor cells. In cases of a highly infiltrative tumor it would not make a significantly different outcome if minimal margins remained. In those instances when tumor cell Identification would increase the log kill without affecting the patient's function, resection would influence survival.
Tumors are often distinguished pre-operatively using CT scanning or MRI. In the operating room these same procedures can assist in the stereotactic marking of the tumor boundaries within several millimeters. These, systems may be cumbersome, costly and may not be available in all centers. The guidance technology has additional limitations due to changes in position after opening the calvarium or dura. Its precision is drastically reduced when brain retraction is used to locate the mass.
Alternate methodology uses tumor specific laser Induced fluorescent spectroscopy. The brain normally autofluorescences between 350 and 650 nm. Brain tumor Interfaces can be identified with or without a vital dye. Without a dye, a laser excites tissue at a wavelength of absorption and in turn the tissue may emit light at another wavelength to aid in identification. In other procedures a vital dye is given, such as, chloro-aluminum phthalocyanine tetrasulfonate, in the rat intracerebral glioma model, which has increased uptake into tumor cells, fluoresces more with laser induction and thus allows for improved tumor resection that may increase survival (1). Another study (2) developed an intra-operative optical imaging technique providing tumor grade and the identification of residual tumor in the resected margins. This work (Continued on page 131)
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