CAAS. II: A second generation system for off-line and on-line quantitative coronary angiography.

The Cardiovascular Angiography Analysis System (CAAS) has been completely redesigned and transferred to a modern platform. The user-friendly environment together with a number of image processing techniques and tools allow easy and fast analysis of cardiovascular angiographic images. These images are obtained either on-line by means of a frame grabber hooked on the video output of the X-ray equipment or off-line by digitising 35-mm cine film frames. In addition, images can be acquired more directly by means of a network link. Images stored on disk in different formats, including MS-DOS, can also be analysed. Accurate and reliable quantitative analysis of coronary stenoses and assessment of their related functional significance may offer the clinician a tool in a stratification of patients at risk. The semireal-time environment will make it possible for the cardiologist to quickly respond to the results of recanalisation procedures while the patient is still in the catheterisation laboratory. The addition of a video front end makes the system available to all clinically relevant X-ray imaging equipment. A detailed comparison with the former CAAS on the basis of analysis of 40 arterial segments in routinely acquired cineangiograms demonstrated no statistically significant differences between the two analysis systems. Repeated analysis of the same segments yielded inter- and intraobserver variabilities for the obstruction diameter of 0.096 and 0.108 mm, respectively. For the computed reference diameter the values are 0.099 and 0.096 mm, respectively, and for the percentage diameter stenosis 4.67 and 5.37%, respectively.