Measurement of regional cerebral blood flow using ultrafast computed tomography. Theoretical aspects.

Theoretical and practical limitations have prevented the measurement of regional cerebral blood flow using dynamic x-ray computed tomography. Development of the ultrafast computed tomography scanner has made it possible to overcome the practical limitations and measure changes in contrast concentration in the brain with excellent time and spatial resolution. By applying modifications of indicator dilution theory, we have derived a method to use these changes in contrast concentration determined using ultrafast computed tomography to measure the fractional vascular volume, mean transit time of blood, and blood flow within specific regions of the brain in a relatively simple and practical manner. This method could theoretically be used in the evaluation of physiological and pathophysiological alterations in cerebral blood flow.