Distribution of 11C-(R)nicotine in human brain measured by positron emission tomography: measurement of cerebral blood flow.

We synthesized 11C-labeled (R)nicotine (11C: a positron-emitting radioisotope with a half-life of 20 min, produced in a cyclotron), and utilized it for blood flow measurement in the human brain. The positron emission tomography was employed for the data acquisition and image reconstruction. The behavior of the isotope was formulated by a mathematical model, consisting of a blood compartment and a tissue compartment, and the time-activity curve in various parts of the brain was analyzed in a computer to obtain a mathematically simulated curve which fell in consistence with both the arterial blood curve and the brain curve. The cerebral blood flow (CBF) value thus determined was compared with the value obtained by the standard C15O2 inhalation method (= H2(15)O method). The nicotine method always gave a higher value than the standard method by 27-34%. It seems that CBF determined by the 11C-(R)nicotine method is more accurate than the value determined by the standard method, because our tracer is superior as a CBF indicator to radiolabeled water.