CT blurring induced bias of quantitative in-stent restenosis analyses

Rational and Objective: In CT systems, blurring is the main limiting factor for imaging in-stent restenosis. The aim of this study is to systematically analyze the effect of blurring related biases on the quantitative assessment of in-stent restenosis and to evaluate potential correction methods. Methods: 3D analytical models of a blurred, stented vessel are presented to quantify blurring related artifacts in the stent diameter measurement. Two correction methods are presented for an improved stent diameter measurement. We also examine the suitability of deconvolution techniques for correcting blurring artifacts. Results: Blurring results in a shift of the maximum of the signal intensity towards the center position of the stent, resulting in an underestimation of the stent diameter. This shift can be expressed as a function of the stent radius and width of the point spread function. The correction for this phenomenon reduces the error with 75 percent. Deconvolution reduces the blurring artifacts but introduces a ringing artifact. Conclusion: The analytical vessel models are well suited to study the influence of various parameters on blurring-induced artifacts. The blurring-related underestimation of the stent diameter can significantly be reduced using the presented corrections. Care should be taken into choosing suitable deconvolution filters since they may introduce new artifacts.