THE CHARACTERISTICS OF LASER-DOPPLER FLOWMETRY FOR THE MEASUREMENT OFREGIONAL CEREBRAL BLOOD-FLOW

THE FUNDAMENTAL CHARACTERISTICS of laser-Doppler flowmetry (LDF), espe cially the depth of cerebral blood flow (CBF) measurement, have not be en widely studied in the brain tissue; however, LDF has been widely us ed in recent clinical and experimental studies. We investigated the de pth of CBF measurement and other characteristics related to the use of LDF in the brain. In an animal experimental study, the distribution o f laser light and the depth of CBF measurement of LDF were measured by using modified LDF probes. CBF in various conditions was also measure d by the LDF and hydrogen clearance method. Laser tight of low output lost directivity and was dispersed into a hemispherical form in the br ain tissue. The depth of CBF measurement was approximately 100 to 400 mu m, depending on the intensity of the emitted laser light, and was n ot affected by changes of CBF. In the physiological condition, the clo se correlation between the values of CBF by the LDF and hydrogen clear ance method was obtained. After cardiac arrest, the CBF value of LDF d id not immediately show a 0 value. LDF has several special characteris tics, and the sample volume was very small. It is important to pay att ention to the several special characteristics of LDF.