Strategy for the Measurement of Regional Cerebral Blood Flow Using Short-Lived Tracers and Emission Tomography

Abstract

This report describes a strategy for measurement of regional CBF that rigorously accounts for differing tracer partition coefficients and recirculation, and is convenient for use with positron emission tomography. Based on the Kety model, the measured tissue concentration can be expressed in terms of the arterial concentration, the rate constant K, and the blood flow f. The local partition coefficient may be computed as p = f/K. In our approach, maps of K and f are computed from two transverse section reconstructions. The reconstructions are based on weighted sums of projection data measured frequently during the observation period. Theoretical studies of noise propagation in the estimates of K and f were carried out as a function of tomographic count rate, total measurement time, and tracer half-life for varying input functions. These calculations predict that statistical errors in f of between 5 and 10% at a resolution of 1 cm full width at half maximum can be obtained with existing tomographs following i.v. injection. To compare theory and experiment, a series of flow studies were carried out in phantoms using a positron tomograph. These measurements demonstrate close agreement between computed flow and noise estimates and those measured in a controlled situation. This close agreement between theory and experiment as well as the low statistical errors observed suggest that this approach may be a useful tool in clinical investigation.

Use of PET Methods for Measurement of Cerebral Energy Metabolism and Hemodynamics in Cerebrovascular Disease

“…Alpert et al (1984) have proposed a different parameter estimation technique: the weighted integration method. This method is a mul tiple scan extension of the original single-scan inte grated projection method by Huang et a!.…”

Quantification of pulmonary blood flow (PBF): Validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with HO positron emission tomography (PET)

“…For the quantification of pulmonary perfusion based on 15 O-labeled water, a model for freely-diffusible tracers was used, taking into account recirculation and differing tracer partition (35). The model comprised a single tissue and a single plasma compartment.…”

A Study of the Single Compartment Tracer Kinetic Model for the Measurement of Local Cerebral Blood Flow Using 15O-Water and Positron Emission Tomography

“…The single compartment model has been used in PET for various measurement pro tocols, which include in vivo autoradiographic (Ginsberg et al, 1982;Herscovitch et al, 1983), steady-state (Subramanyam et al , 1978;Jones et al , 1976), and dynamic measurement techniques (Yamamoto et al, 1977;Kanno et al, 1979;Huang et al , 1983;Alpert et al, 1984). Most of these methods require the introduction of 150-water through inhalation of 150-C02 or direct intravenous injection.…”