1. A method for automatically detecting pulmonary embolism candidates within medical image data using an image processing device, comprising: administering a contrast agent into a patient; acquiring a plurality of images; automatically determining by the image processing device a level of contrast agent at a pre-determined anatomic location of the patient, wherein the pre-determined location is the pulmonary artery trunk, comprising: automatically identifying by the image processing device the pre-determined anatomic location within an image frame of the plurality of images; locating by the image processing device a point within the automatically identified pre-determined anatomic location; identifying by the image processing device a neighborhood of points around the located point; determining by the image processing device the intensity of each point in the neighborhood of points; selecting by the image processing device a group of the high intensity points within the neighborhood of points; averaging by the image processing device the intensity of the selected group of high intensity points; and determining by the image processing device the level of radiocontrast agent at the pulmonary artery trunk based on the average intensity; and detecting by the image processing device one or more pulmonary embolism candidates based on the determined level of contrast agent at the pulmonary artery trunk.