THE REQUIREMENT FOR CONSTANT ARTERIAL RADIOACTIVITY IN THE (CO2)-O-15 STEADY-STATE BLOOD-FLOW MODEL

  • 1 January 1984
    • journal article
    • research article
    • Vol. 25  (4) , 455-460
Abstract
The discrepancy was evaluated between the true CBF [cerebral blood flow] value and the CBF value calculated according to the C15O2 steady-state model; this was done to investigate situations in which the arterial input function, Ca(t), deviates considerably from its steady-state value, Ca [where Ca is the arterial 15O2 concentration]. The fact that arterial input function and tissue 15O concentration are not independent variables is taken into account. In constant or viarable arterial input functions are simulated and the corresponding tissue 15O concentrations calculated. The steady-state CBF values are evaluated for several temporal variations of Ca over the period of imaging, all derived fromf Ca(t) by simulation of various blood-sampling schemes, and are compared with the ture CBF value. Reliable CBF values can be obtained by the C15O2 steady-state method even under severely impaired unsteady-state conditions, previded that either the ture average arterial concentration over the entire scan, or the average concentration from multiple arterial samples, is used. [15O2 is used as diagnostic agent for brain studies.].