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

Rationale and Objectives. The purpose of this study was to evaluate a metho d that uses electron-beam computed tomography to obtain the most appropriat e starting level for complete imaging of the coronary tree and to compare i t with the existing method. A second aim was to evaluate the spatial locati on of the coronary arteries relative to different anatomic cardiac and ches t landmarks. Materials and Methods. Two hundred forty consecutive patients were randomly assigned to imaging with either a six-level preview (new) method or the tr aditional 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 startin g 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 art ery in 33 patients (14%). The coronary arteries were encompassed by scans d epicting 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 coron ary arteries and the pulmonary artery or carina could be found. Conclusion. The six-level preview method that identifies the left main coro nary artery and begins 9 mm above this level is the most accurate method fo r depicting the coronary anatomy. No anatomic landmarks in the heart or che st can be used reliably to identify the position of the coronary arteries i n individual patients.