Streak artifact reduction in cardiac cone beam CT

摘要

Cone beam reconstructed cardiac CT images suffer from characteristic streak artifacts that affect the quality ofcoronary artery imaging. These artifacts arise from inhomogeneous distribution of noise. While in non-taggedreconstruction inhomogeneity of noise distribution is mainly due to anisotropy of the attenuation of the scannedobject (e.g. shoulders), in cardiac imaging it is largely influenced by the non-uniform distribution of the acquireddata used for reconstructing the heart at a given phase. We use a cardiac adaptive filter to reduce these streaks. Indifference to previous methods of adaptive filtering that locally smooth data points on the basis of their attenuationvalues, our filter is applied as a function of the noise distribution of the data as it is used in the phase selectivereconstruction. We have reconstructed trans-axial images without adaptive filtering, with a regular adaptive filterand with the cardiac adaptive filter. With the cardiac adaptive filter significant reduction of streaks is achieved, andthus image quality is improved. The coronary vessel is much more pronounced in the cardiac adaptive filteredimages, in slab MIP the main coronary artery branches are more visible, and non-calcified plaque is betterdifferentiated from vessel wall. This improvement is accomplished without altering significantly the borderdefinition of calcified plaques.