Leonidas Georgiou1,2, Chris James Rose1,2
Tracer kinetic model parameters typically have physiological interpretations, and constraints exist between them. While most fitting routines can impose constraints on parameters individually, this is not so for inter-variable constraints. Irrespective of the accuracy of the model itself, non-physiological parameter estimates will result in erroneous inferences being drawn about tumour microvascular characteristics. We study the frequency with which non-physiological fits occur in clinical data, propose a method with which those constraints can be imposed and, using simulations, compare the proposed solution to the conventional approach. We show that imposing inter-parameter constraints can result in more accurate and precise parameter estimates.