Real Time Visualization of Volume Data: Applications in Computed Tomography Angiography

Abstract

The development of 1-s rotation spiral computed tomography (CT), soon followed by subsecond spiral CT (0.75 s) and, more recently, multislice CT (MSCT), represent far more than the ability to acquire more individual scans in a shorter period of time or the ability to complete a scan of a patient in a single breath hold [1, 2]. Rather, the development of these scanners provides, for the first time, true volume data sets which represent the potential for an entirely new paradigm in medical imaging. That is, the ability to scan a chest or abdomen with narrow collimation, in a single breath hold, optimized for contrast enhancement provides an entirely new possibility of our ability to image the patient. This new paradigm is not simply that the use of film is not ideal and that computer-based viewing (PACS network) with a trackball is needed. Rather, it emphasizes that scrolling through a data set with a trackball is also unsatisfactory as the image data set grows from 60 to 100 to 200 to 500 to 1000 images per patient study. Even if a trackball became easier to use and the PACS system more user friendly, a truth would soon emerge. That is that the information seen on axial CT alone is in fact very limited for some applications and totally unsatisfactory for many other applications. While axial images are fine to detect a tumor in the liver, the axial mode might not be ideal in defining the relationship of the tumor to the portal vein, or whether the tumor is resectable for potential cure Axial images surely are limited for analyzing vascular images, such as a CT angiogram of the aorta, celiac axis, or carotid artery. This limitation is obvious to the radiologist but even more obvious to the referring physician, such as a vascular surgeon, an oncologic surgeon, or a trauma surgeon.