Partial volume averaging
Partial volume artifact occurs when tissues of widely different absorption are encompassed on the same CT voxel producing a beam attenuation proportional to the average value of these tissues.
The latest generation of CT scanners with an associated reduction in the volume of a voxel has substantially reduced the occurrence of this artifact.
Partial volume averaging is particularly problematic in CT angiography (e.g. misdiagnosis of an apparent contrast filling defect caused by the artifact as PE). Therefore the use of thin section reconstructions (1-1.5 mm) are recommended where the impact of this artifact is negligible .