[Topographic mapping of regional cerebral blood flow by xenon-enhanced CT--introducing a simplified method as a routine examination].

Measurement of regional cerebral blood flow (rCBF) has become a routine examinations in the field of clinical neurology and neurosurgery. Therefore, various methods for measuring rCBF have been developed. Among them, xenon-enhanced CT method has many advantages compared with others. An obtainable topographic flow map, high anatomical spatial resolution, and readily available instrument, namely CT scanner, are regarded as the advantages. On the one hand, anesthetic effects of xenon gas on the patients, taking a great expense for a single examination, and a significant dose of radiation delivered to the patients are thought to be the disadvantages. Due to the disadvantages, xenon-enhanced CT is regarded as an unpractical examination. In the paper, we introduce a method with a brief xenon inhalation, named a simplified method, with which the disadvantages can be avoided. Conventional xenon-enhanced CT requires 20 to 25 minute inhalation of xenon gas in order to achieve a saturation of xenon in the cerebral tissue for a calculation of the partition coefficients (L). In the simplified method, instead of using the calculated L, L was given as 1.0 in all the cerebral regions and xenon gas was terminated at 4 minute inhalation. Four minute inhalation of xenon gas did not make any significant anesthetic effects on the patients nor the changes of physiological parameters, such as, PaCO2 and blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)