Framework for Computer-aided Detection of Pulmonary Embolism

In this paper, we present a framework for computer-aided diagnosis of pulmonary embolism (PE) in contrast-enhanced computed tomography (CT) images. It consists of a combination of a method for segmenting the pulmonary arteries (PA), emboli detection methods as well as a scheme for the evaluation of the performance. The segmentation of the PA serves one of the clot detection methods, and is carried out through a region growing method that makes use of a priori knowledge of vessels topology. Two different approaches for clot detection are introduced: the first one performs clot detection by analysing the concavities in the segmentation of the pulmonary arterial tree. It works in a semi-automatic way and enables the detection of thrombi in the larger sections of the PA. The second method does not make use of the segmentation and is thus fully automatic, enabling detection of the clots farther in the vessels. The combination of these methods provides a robust detection of clots that can be used as a safeguard by radiologists, or even as preliminary computer-aided detection (CAD) toolset. The evaluation of the method is also discussed, and a scheme for measuring its performance in terms of sensitivity and specificity is proposed, including a practical approach to making reference detection data, or ground truths, by radiologists. Results are presented and discussed.