a collaborative resource to build consensus for automated left ventricular segmentation of cardiac mr images a collaborative framework was initiated to establish a community resource of ground truth segmentations from cardiac mri multisite multivendor cardiac mri datasets comprising 95 patients 73 men 22 women mean age 62731124years with coronary artery disease and prior myocardial infarction were randomly selected from data made available by the cardiac atlas project fonseca et al 2011 three semi and two fullyautomated raters segmented the left ventricular myocardium from shortaxis cardiac mr images as part of a challenge introduced at the stacom 2011 miccai workshop suinesiaputra et al 2012 consensus myocardium images were generated based on the expectationmaximization principle implemented by the staple algorithm warfield et al 2004 the mean sensitivity specificity positive predictive and negative predictive values ranged between 063 and 085 060 and 098 056 and 094 and 083 and 092 respectively against the staple consensus spatial and temporal agreement varied in different amounts for each rater staple produced high quality consensus images if the region of interest was limited to the area of discrepancy between raters to maintain the quality of the consensus an objective measure based on the candidate automated rater performance distribution is proposed the consensus segmentation based on a combination of manual and automated raters were more consistent than any particular rater even those with manual input the consensus is expected to improve with the addition of new automated contributions this resource is open for future contributions and is available as a test bed for the evaluation of new segmentation algorithms through the cardiac atlas project wwwcardiacatlasorg