Quantitative evaluation of graded hindlimb ischemia based on pharmacokinetic modelling and hemodynamic analysis of indocyanine green.

OBJECTIVE: Accurate evaluation of the degree of hindlimb ischemia is challenging but essential for the diagnosis and treatment of peripheral vascular insufficiency. The aim of the study is to apply a multiparametric method for the quantitative estimation of mouse models with different degrees of hindlimb ischemia based on a dynamic fluorescence imaging-based strategy.

APPROACH: An adjustable hydraulic occluder was placed around the thigh root of one hindlimb to induce six different degrees of hindlimb ischemia. Five parameters were extracted to quantitatively evaluate the degree of ischemia, including perfusion rate (PR) and perfusion vascular density (PVD) from a mathematical model of indocyanine green (ICG) pharmacokinetics, rising time (T rise ), blood flow index (BFI) and mean fluorescence intensity (MFI) from time-series analysis of ICG hemodynamics.

MAIN RESULTS: The results showed that the normalized PR and BFI decreased while the normalized T rise increased progressively with the degree of ischemia. The normalized PVD and MFI first increased and then decreased with the degree of ischemia. High correlation was observed between the degree of ischemia and the arterial oxygen saturation which was measured by an oximeter.

SIGNIFICANCE: The results of this work demonstrated that PR, BFI and T rise can be used for the quantitative and comprehensive evaluation of graded hindlimb ischemia.