Functional Molecular Imaging In Hepatology

The eBook discusses how the special physiology of the liver must be considered when applying functional molecular imaging in hepatology. The main topics of the eBook include the clinical and ...
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Combining Compartmental and Microvascular Models in Interpreting Dynamic PET Data

Pp. 24-31 (8)

Ole Lajord Munk, Susanne Keiding and Ludvik Bass

Abstract

Measurement of hepatic blood perfusion and of the exchange of substances between blood and cells is a challenge. Long before the development of PET, multiple indicator data were analysed using models based on elaborate capillary theories. Today, PET is a unique modality that allows external quantitative measurements of the regional distribution of intravenously injected radiotracers and their metabolites in tissues, but dynamic PET data are analysed using less physiologically based schemes. The standard compartment model is an inlet equilibration model that does not naturally incorporate blood flow, and a single-uptake model that does not allow substances to re-enter the capillaries. These deficiencies lead to paradoxes when modelling fast blood-cell exchange. We have combined compartmental and capillary theory and developed microvascular models that account for blood flow and concentration gradients in capillaries. The microvascular models can be regarded as revisions of the input function which include more physiological realism and provide a superior description and interpretation of dynamic PET data when compared to the standard compartmental scheme.

Keywords:

PET kinetics; Blood flow; Capillaries, Microcirculation.

Affiliation:

PET Centre, Aarhus University Hospital, Aarhus, Denmark