MPR

　　MPR is the basic tool used to interpret cardiac CT angiographic studies. With use of retrospective electrocardiographic gating, data from specific phases of the cardiac cycle are retrospectively referenced to the electrocardiogram for reconstruction. Once the reconstruction is complete, the data are transferred directly to the workstation. The radiologist then interfaces with the reonstructed series in real time at the workstation. Because of variations in the orientation of the heart in the thorax, it is often useful to evaluate cardiac structures along the cardiac planes. The multiplanar capabilities of the workstation allow images of the heart and coronary arteries to be manually rotated for optimal evaluation of the cardiac anatomy. Most workstations with cardiac analysis capabilities can automatically orient volumetric image data sets along the cardiac axes and into the traditionally used cardiac planes (ie,short-axis, horizontal long-axis, vertical long-axis)with the click of a button. This feature is especially useful for evaluating the cardiac chambers and left ventricular (LV) function. Selected reformatted images are sent to the picture archiving and communication system (PACS) for review by the referring clinicians and for long-term storage.

　　(a) Axial MPR image displays the origin of the coronary arteries from the aorta. The LCA (black arrow) bifurcates into the left anterior descending (LAD) artery (white arrowhead) and the left circumflex (LCx) artery (black arrowhead). White arrow indicates the right coronary artery (RCA). (b) VR image shows the LCA (black arrow) arising from the aorta and bifurcating into the proximal LCx artery (arrowhead) and the proximalLAD artery (white arrow).