Preview method for electron-beam CT scanning of the coronary arteries

Rationale and Objectives. The purpose of this study was to evaluate a method that uses electron-beam computed tomography to obtain the most appropriate starting level for complete imaging of the coronary tree and to compare it with the existing method. A second aim was to evaluate the spatial location of the coronary arteries relative to different anatomic cardiac and chest landmarks. Materials and Methods. Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the traditional preview method. The accuracy of each preview method to encompass the coronary anatomy was compared. Results. All coronary arteries were included in 3-mm scans obtained starting three levels above the origin of the left main coronary artery. The left anterior descending coronary artery extended 3-9 mm above the left main artery in 33 patients (14%). The coronary arteries were encompassed by scans depicting 72-105 mm; thus, with 3-mm sections, up to 35 scans are necessary to cover the entire coronary tree. No stable relationship between the coronary arteries and the pulmonary artery or carina could be found. Conclusion. The six-level preview method that identifies the left main coronary artery and begins 9 mm above this level is the most accurate method for depicting the coronary anatomy. No anatomic landmarks in the heart or chest can be used reliably to identify the position of the coronary arteries in individual patients.