Regional cerebral perfusion measurements: a comparative study of xenon-enhanced CT and C15O2 build-up using dynamic PET

Regional cerebral perfusion can be determined by monitoring the uptake of a diffusable tracer concurrently in cerebral tissue and arterial blood. Two techniques based on this methodology are xenon-enhanced computed tomography (Xe CT) and C15O2 build-up using dynamic positron emission tomography (C15O2 PET). Serial images are used by both Xe CT and C15O2 PET to characterize the uptake of the tracer in cerebral tissue. The noise present in these images will reduce the precision of the perfusion measurements obtained by either technique. Using Monte Carlo type computer simulations, the precision of the two techniques as a function of image noise has been examined. It is concluded that the precision of the Xe CT technique is comparable to the precision of C15O2 PET when realistic clinical protocols are employed for both.