Efficiently obtaining a reliable coronary artery centerline from computed tomography angiography data is relevant in clinical practice. Whereas numerous methods have been presented for this purpose, up to now no standardized evaluation methodology has been published to reliably evaluate and compare the performance of the existing or newly developed coronary artery centerline extraction algorithms. This paper describes a standardized evaluation methodology and reference database for the quantitative evaluation of coronary artery centerline extraction algorithms. The contribution of this work is fourfold: 1) a method is described to create a consensus centerline with multiple observers, 2) well-defined measures are presented for the evaluation of coronary artery centerline extraction algorithms, 3) a database containing thirty-two cardiac CTA datasets with corresponding reference standard is described and made available, and 4) thirteen coronary artery centerline extraction algorithms, implemented by different research groups, are quantitatively evaluated and compared. The presented evaluation framework is made available to the medical imaging community for benchmarking existing or newly developed coronary centerline extraction algorithms.

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Purpose: To characterize the extent and distribution of left ventricular myocardial scar in delayed enhancement magnetic resonance imaging (MRI). Materials and Methods:Delayed enhancement images from 18 patients were categorized into three groups based on myocardial scar appearance: discrete myocardial infarction (N ϭ 10), diffuse fibrosis (N ϭ 4), and circumferential endocardial scarring (N ϭ 4). Images were segmented manually by two observers (twice by one observer) to identify nonviable myocardium. Scar was characterized by the following morphologic parameters: the relative area of nonviable myocardium (Percent Scar); a measure of scar cohesion (Patchiness); and the extent to which scar traversed the ventricle wall (TransϾ50). Results:The three scar parameters successfully discriminated between patient groups, although no one parameter was able to differentiate between all groups. The average bias between readers was approximately 3% for each parameter, and the average bias between repeated measurements was 1%. In addition, five patients exhibited regions of nonhyperenhanced nonviable myocardium that were expected to show hyperenhancement based upon their location within the infarct zone and appearance on cine images. Conclusion:Quantitative characterization of myocardial scar showed good interobserver and intraobserver agreement. However, the appearance of nonhyperenhanced scar in chronic ischemia is problematic for segmentation of delayed enhancement images. CHARACTERIZING THE LOCATION and extent of myocardial injury due to infarction or chronic ischemia of the left ventricle (LV) is essential for proper clinical management of affected patients (1,2). It has been shown that patients with regions of hypocontractile yet viable myocardium benefit from reperfusion therapy or revascularization (3-5); furthermore, that the relative contributions of viable and nonviable tissue within a given segment of myocardium are related to the ultimate success of reperfusion (4 -6). However, most noninvasive techniques for assessing myocardial viability lack sufficient spatial resolution or tissue characterization capabilities to discriminate between viable and nonviable tissue within the LV wall (e.g., stress cine MRI, stress echocardiography, nuclear radiographic techniques); the most widely accepted reference standard for identifying viable myocardium remains recovery of function after revascularization (7).Delayed hyperenhancement (DE) of nonviable myocardium in contrast-enhanced magnetic resonance imaging (MRI) has been described in numerous previous studies (4 -6,8 -12), and the close correspondence between the area of hyperenhancement and infarct extent and distribution has been well established (10,13). Furthermore, DE-MRI has sufficient resolution to accurately distinguish viable (normal or ischemic) from nonviable LV myocardium (14).Qualitative or semiquantitative analysis of DE-MRI images can be subjective, which limits direct comparison of results between sequential studies and might limit its clinical application...

Abstract. Delayed Enhancement MR is an imaging technique by which nonviable (dead) myocardial tissues appear with increased signal intensity. The extent of non-viable tissue in the left ventricle (LV) of the heart is a direct indicator of patient survival rate. In this paper we propose a two-stage method for quantifying the extent of non-viable tissue. First, we segment the myocardium in the DEMR images. Then, we classify the myocardial pixels as corresponding to viable or non-viable tissue. Segmentation of the myocardium is challenging because we cannot reliably predict its intensity characteristics. Worse, it may be impossible to distinguish the infracted tissues from the ventricular blood pool. Therefore, we make use of MR Cine images acquired in the same session (in which the myocardium has a more predictable appearance) in order to create a prior model of the myocardial borders. Using image features in the DEMR images and this prior we are able to segment the myocardium consistently. In the second stage of processing, we employ a Support Vector Machine to distinguish viable from non-viable pixels based on training from an expert.

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