Comparing One-Stage and Two-Stage Model Fitting Approaches in Multi-TE ASL for Blood-Brain Barrier Permeability Assessment

Motivation: This study investigates parameter interdependence in multi-echo-time ASL modeling of blood-brain barrier permeability and related parameters. Goal(s): The goal is to compare one-stage and two-stage fitting approaches for estimating CBF, ATT, Tex, and ITT. Approach: Using simulations, we conducted a comparative analysis, applying a one-stage, two-compartment model versus a two-stage approach where CBF and ATT were first estimated with the Buxton model. Results: Our findings show that Tex estimation remained relatively stable in both approaches, but in two-stage approach CBF underestimation propagated errors into ITT, highlighting the need to consider model assumptions and parameter cross-dependencies in two-stage approaches. Impact: This study shows that two-stage approaches, using different models in each stage, risk error propagation due to parameter cross-dependence. These insights are essential for developing more accurate, clinically applicable BBB imaging models that improve parameter reliability.