A Period of Refinement

Quantitative coronary arteriography (QCA) is an important tool for studying the effects of coronary interventions in the catheterisation laboratory in an accurate and reproducible manner. Nowadays, peer-reviewed publications on relevant interventional trials are only accepted if the vascular interpretations are presented in quantitative terms, whereby the degree of restenosis, and the so-called late lumen loss, are the most relevant parameters.

Important technical developments in the catheterisation arena over the past 15 years have included the digitisation of the catheterisation laboratories, whereby the conventional 35mm cinefilm was replaced by the digital CD. Furthermore, the image data is now stored in digitial imaging and communications in medicine (DICOM) format. This greatly simplifies the transfer of the image data on digital copies to other physicians and the imaging core laboratories (ICLs), where they can be analysed without any loss of information.

In the last few years, an increasing number of cardiovascular X-ray imaging systems have been equipped with flat-panel detectors, replacing the conventional vacuum tube image intensifier in combination with a CCD camera. There are a number of major advantages to these flat-panel detectors, which include the ability to preserve significantly more of the original digital signal and the absolute absence of spatial distortions, thereby providing superior image quality and enabling further image enhancement. In clinical practice, this means improved visibility of vessels, lesions, stents and guidewires, even at reduced X-ray dose levels.

The great advantage of a QCA analysis is that the sizes of the selected coronary segments can be determined from the coronary arterial arteriograms in a standardised manner according to standard operating procedures (SOPs) with robust and automated contour detection techniques. A typical example of a QCA analysis in a circumflex artery is given in Figure 1.