ABSTRACT
A very large number of methods have been used in an attempt to quantify blood flow in organs and vessels in the intact body. This chapter examines the basic techniques and describe briefly the different applications, before moving on to methods for measuring blood velocity. The indicator could be a dye, an isotope, a gas—anything in fact which is transported by the blood, which is acceptable to the body, and the concentration of which can be measured. Blood is an inhomogeneous suspension, in which the cells travel faster than the plasma. A small quantity of dye is injected into the venous bloodstream close to the heart through a catheter. Positron emitters have been used for the study of regional cerebral blood flow, using positron-emission tomography. The chapter looks at the principles of some of these techniques, but only examine the measurement of tissue blood flow in any detail.
