Artifacts Reduction in Temporal Subtraction Images of Thick-Slice CT Images

Abstract

Temporal subtraction is a technique that calculates a subtraction image of a pair of registered images acquired from the same patient at different time points. Past studies have shown that the technique is effective in visualizing pathological changes over time, and therefore, it has been expected to be a supporting tool for medical doctors in radiological interpretation. However, in case of thick-slice images (which are widely used in actual clinical practice), even with an accurate image registration, artifacts caused by partial volume effects have deteriorated quality of the subtraction image. In this study, we proposed a method that reduces such artifacts by considering gaps of discretizing position based on the slice thickness of the two input images in the calculations of the subtraction. In this paper, we evaluated the proposed method in the following two ways: 1) quantitative evaluation using synthetic data and 2) radiologists' subjective evaluation using clinical data. Our results show that, in terms of both quantitative evaluation and radiologists' subjective evaluation, the proposed method was superior to the conventional subtraction method.