Purpose: To devise a noninvasive imaging method for resolving the relative contribution of splenic and splanchnic blood flow to portal venous flow and derive quantitative estimates for parameters pertaining to splenic and portal hemodynamics.
Methods: Tracer concentration-time curves of the aorta, portal vein, and spleen can be extracted from dynamic contrast-enhanced (DCE) CT or MR images. A combination of two tracer analysis approaches, namely arterial-venous sampling and residual tracer deconvolution, is proposed to model these concentration-time curves and derive hemodynamic parameters pertaining to splenic and portal circulation. Clinical feasibility of the proposed method was explored using DCE CT datasets of eight cirrhotic patients. Monte Carlo simulations were performed to evaluate the confidence of the parameter estimates.
Results: Portal blood flow was estimated to be 763.8 +/- 438.1 ml/min in cirrhotic patients and the splenic contribution was found to be elevated (0.75 +/- 0.22). Estimates of splenic blood flow (582 +/- 420 ml/min) and transit time (15.3 +/- 10.1 s) in cirrhotic patients were consistent with reported values obtained using duplex Doppler ultrasound and dynamic scintigraphy, respectively.
Conclusions: This study shows the feasibility of noninvasive assessment of splenic and portal hemodynamic parameters by DCE imaging using a combination of tracer kinetics modeling techniques.