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Noninvasive angiographic evaluation of coronary stents with multi-slice spiral computed tomography
Koen Nieman1, Filippo Cademartiri, Rolf Raaijmakers
1Department of Cardiology, Erasmus Medical Center & Thoraxcenter, Rotterdam, The Netherlands. koennieman@hotmail.com
Insights
Computed tomography (CT) imaging of coronary artery stents is challenging due to artifacts. While CT can detect stent occlusion, subtle in-stent issues remain difficult to assess accurately.
Area of Science:
- Cardiovascular imaging
- Medical device assessment
- Radiology
Background:
- Increasing prevalence of obstructive coronary artery disease necessitates effective stent evaluation.
- ECG-gated multi-slice spiral CT (MSCT) offers noninvasive coronary artery imaging as an alternative to angiography.
- Assessing coronary stents with CT presents significant challenges due to image artifacts.
Purpose of the Study:
- To evaluate the feasibility and image characteristics of coronary stents using CT.
- To understand the nature and impact of CT artifacts on stent visualization.
- To determine the current clinical utility of CT for post-percutaneous coronary intervention assessment.
Main Methods:
- In vitro experiments with varying CT parameters (collimation, contrast, stent size/position).
- In vivo imaging to assess stent characteristics in a clinical setting.
- Analysis of stent-related artifacts, including the blooming effect.
Main Results:
- High-density artifacts ('blooming') expand the apparent size of stent struts.
- The blooming artifact is relatively less pronounced in larger-diameter stents.
- In vivo imaging is further complicated by motion, lower contrast-to-noise ratio, and vessel calcifications.
Conclusions:
- Current CT utility is limited to detecting stent occlusion and non-stented segment disease progression.
- Subtle abnormalities within coronary stents are not reliably visualized by CT.
- Future improvements may involve scanner technology advancements and the use of less radiopaque stent materials.
Background:
The number of patients with obstructive coronary artery disease, who undergo coronary angioplasty with implantation of stents, is ever increasing. As an alternative to catheter-based angiography, ECG-gated multi-slice spiral computed tomography (MSCT) allows noninvasive imaging of the coronary arteries. However, coronary stents have been notoriously difficult to assess by CT.
Methods And Results:
In vitro experiments were performed, using varying detector collimations, contrast concentrations, stent positions and stent diameters, to evaluate the feasibility and image characteristics of stents. The stent-related high-density artifacts expand the apparent size of the stent struts. This blooming effect is a fairly constant phenomenon, and therefore relatively less evident in larger-diameter stents. The in vivo images show the same artifacts, but assessment is further complicated by motion, lower contrast-to-noise, and vessel wall calcifications.
Conclusions:
The clinical value of CT after percutaneous coronary intervention currently remains largely limited to the detection of stent occlusion, and the progression of coronary artery disease in the remaining nonstented segments. Subtle in-stent abnormalities cannot be reliably imaged. Some relief will be offered by improvements in scanner technology, but the use of less radiopaque stent material would be more effective.