Volumetric Quantification of Atherosclerotic Plaque in CT Considering Partial Volume Effect

Abstract

Abstract-Coronary artery calcification (CAC) is quantified based on a computed tomography (CT) scan image. A calcified region is identified. Modified expectation maximization (MEM) of a statistical model for the calcified and background material is used to estimate the partial calcium content of the voxels. The algorithm limits the region over which MEM is performed. By using MEM, the statistical properties of the model are iteratively updated based on the calculated resultant calcium distribution from the previous iteration. The estimated statistical properties are used to generate a map of the partial calcium content in the calcified region. The volume of calcium in the calcified region is determined based on the map. The experimental results on a cardiac phantom, scanned 90 times using 15 different protocols, demonstrate that the proposed method is less sensitive to partial volume effect and noise, with average error of 9.5% (standard deviation (SD) of 5-7mm 3 ) compared with 67% (SD of 3-20mm 3 ) for conventional techniques. The high reproducibility of the proposed method for 35 patients, scanned twice using the same protocol at a minimum interval of 10 min, shows that the method provides 2-3 times lower interscan variation than conventional techniques.Index Terms-Coronary artery calcification, expectation-maximization, partial volume effect, proportion map, volume measurement.

ACCURATUM: improved calcium volume scoring using a mesh-based algorithm—a phantom study

“…An average error of 9.5% with a standard deviation of 5-20% was achieved on a cardiac phantom. However, as Dehmeshki et al [28] used a 16-slice CT system and some CT protocols that were not completely defined, a direct comparison with our results was not feasible.…”

“…Dehmeshki et al [28] proposed another approach for the volume measurement of calcified plaques. Their algorithm used a modified expectation maximization of a statistical model for the plaque volume measurement.…”

Segmenting the Femoral Head and Acetabulum in the Hip Joint Automatically Using a Multi-Step Scheme

“…Since the intensity values of bone, especially for cortical bone, are statistically higher than the intensity of the surrounded tissue, an intensity threshold can be detected such that the intensities of most pixels of bone are greater than the threshold value, so global threshold is a commonly used method in the automated segmentation of bone from CT images [4]. However, due to the narrow inter-bone regions as well as weak and diffused boundaries in pelvis and femur, it is seldom possible to find a threshold that is less than values of all bone and greater than values of all other tissues.…”

“…However, clinical complications such as osteoarthritis and congenital deformities, technical limitations of CT imaging like inherent blurring and partial volume effect, and the narrow interbone regions and the presence of blood vessels in the bone tissues often result in textured regions, as well as weak and diffused boundaries in pelvis and femur images. Threshold-based techniques have been widely used in segmentation of the bone from CT images [2]- [4]. This type of segmentation is fairly successful in general since the CT values of bone are greater than those of the surrounding soft tissues.…”

Cardiac CT: Practical approach to integrate appropriate indications in daily practice

“…However, the role seems to be largely underused, especially in Europe. Basically, the historic coronary calcium score (CCS) described by Agatston et al [20] is still the reference despite reported convincing improvements both in the detection and in the quantification processes [21,22]. The use of the CCS is mainly justified by the extensive literature and evaluation of the method during the last decades.…”