MULTISLICE CT CORONARY ANGIOGRAPHY IN THE CLINICAL PRACTICE

In the last 6 years, there has been an unprecedented development in the multislice CT technology, thus gradually incorporating it to the diagnosis techniques of clinical cardiology.

Due to its capacity of visualizing the light and the coronary arteries wall in a non-invasive way and also obtaining information about the presence, severity and characteristics of the atherosclerotic plaques, it has become an attractive alternative to the previously available diagnosis tools, such as nuclear medicine perfusion images or invasive selective coronary angiography, for the assessment of patients with known or suspected coronary disease.
The current generation of 64-slice CT provides 0.4 mm planar resolution, 0.6 mm slice thickness and temporary 165 mseg resolution. The simultaneous acquisition of 64 parallel axial sections allows the acquisition of images from the coronary tree in approximately 10 seconds (half of the time it used to take with 16-slice machines).

Recent studies have shown that 64-slice CT provides excellent diagnosis accuracy for the detection of significant stenosis, even in small coronary segments (86%-94% sensitivity and 93%-95% specificity, compared to invasive coronariography, such as gold standard). Its high negative predictive value (about 95%-97%) suggests that 64-slice CT angiography can rule out the presence of hemodynamically significant coronary disease. This represents a remarkable improvement regarding multislice CT machines with lower amount of detectors, mainly achieved by a significant decrease in the number of non-assessable segments, which represent a 7% in 64-slice machines, compared to a 20% in 16-slice tomographs.

Below you will find a summary of the main clinical indication for multislice CT coronariography in the current cardiologic practice.

A- Suspected Coronary Disease
A “normal” multislice CT angiography allows the professional to rule out the presence of hemodynamically significant coronary stenosis, with a high rate of accuracy. Within a clinical context, the high negative predictive value of this method can be useful to avoid invasive coronariography in patients in which their symptoms, or the outcomes of functional studies, lead to a more exhaustive assessment in order to rule out the presence of coronary disease.

This is especially suitable for patients whose age, gender or symptoms suggest a low or intermediate probability of suffering from significant coronary disease. Within this group, we can find patients that show atypical thoracic pain or those in which the outcomes of the gamma camera myocardial perfusion show no correlation with the clinical results.

B- Follow-Up Alter Myocardial Revascularization Surgery.
Several studies have shown that multislice CT angiography allows a highly-accurate assessment of the permeability of coronary bridges (near 100% for occlusion detection in most published studies). With 64-slices machines not only excellent vein and artery graft images can be obtained but we can also reduce scanning time and assess the native coronary vasculature, which is highly relevant in the therapeutic decision-making.

C- Coronary Anomalies
Multislice CT coronary angiography has proved to be extremely useful to identify patients with coronary artery anomalies. The presence of a coronary anomaly can be a differential diagnosis in patients with suspected coronary disease, thoracic pain or syncope. The exhaustive assessment of anomalous coronary arteries, in relation to its origin and course, can be tricky to carry out with invasive coronariography. The tridimensional nature of multislice CT coronary angiography, its high resolution and image acquisition speed allow the analysis of even the smallest details of coronary anomalies. That is why it is reasonable to use multislice CT as the selection method in the assessment of known or suspected coronary anomalies.

Undoubtedly, the growth of multislice CT diagnosis in the cardiologic area offers us new diagnosis tools and, at the same time, generates new investigation lines in the assessment of the coronary disease.

This topic will be part of the upcoming SOLACI Congress 2007, where we will have the chance to exchange opinions and clear up doubts with renowned international and Latin American professors.



Fig. 1: Tridimensional view of normal heart and coronary tree.
Fig. 2: Atherosclerotic lesions viewed through a 64-slice CT in anterior descending artery.

Special thanks to Dr. Enrique Gurfinkel and Dr. Carolina Glaser for the contribution.

« Back to News