Simulating the effect of venous dispersion on distribution volume measurements from the Logan plot

Abstract

Measurement of distribution volume with the Logan plot requires an arterial time activity curve (TAC). The gold standard for measuring arterial activity concentrations is arterial blood sampling. Arterial cannulation carries with it several risks. This work simulated the effects of venous dispersion on measured distribution volumes using the Logan plot with a venous TAC. A representative arterial TAC was selected from a patient study. Simulated tissue TACs were generated from a three compartment kinetic model using the representative arterial TAC. Venous TACs were simulated by convolving the arterial TAC with modified transit time spectra derived from an in vivo dynamic contrast enhanced-CT forearm study. Gaussian noise was added to the tissue TACs. Logan analysis was compared using the arterial and venous TACs for a wide range of kinetic parameters. Bland–Altman analysis was performed to assess agreement between the two methods. Good agreement was observed between values calculated with the arterial and simulated venous TACs for both noiseless and noisy cases. Agreement was slightly dependent on the arterio–venous extraction efficiency of the PET tracer. Results suggest that venous sampling may be a feasible alternative to arterial sampling for analysis with the Logan plot. This technique must be clinically validated in future patient studies.