Purpose: to assess the value of the new high spatial resolution 64-slice CT (0.4 mm collimation) technology for non-invasive visualization of coronary artery stent lumen and the characterization of significant in-stent restenosis.
Materials and methods: a total of 100 stents were visualized in 50 consecutive patients. All CT examinations were performed with a 64-slice CT (sensation 64; Siemens), with a slice thickness of 0.75 mm at 0.5 mm intervals with retrospective gating. Images were evaluated by two readers and the quality of the in-stent lumen was classified on 5-point scale (1 = not visible; 5 = excellent visibility). Fifty-eight stents in 29 patients were also examined by conventional coronary angiography one week after CT examination. Attenuation values were measured in the vessel upstream from the stent and within the stent, using 1 mm2 regions of interest. The intra stent attenuation ratio (ISAR) was calculated as vessel enhancement/intra stent hypodense area. Interobserver agreement was evaluated by kappa statistics,
Results: the interobserver agreement was k= 0.82. The in-stent lumen was visible (score > or =3) in 88 stents (88%), with good visibility (> or = 4) in 54% of stents. Unsatisfactory in-stent lumen visibility was associated with heart rate > 65 beat/min (p < 0.001) and stent size < 3 mm (p < 0.0001). In-stent visibility was also lower in circumflex than other arteries (p= 0.02). Thirteen stenoses or occlusions were detected in 8 patients. In-stent restenosis was associated with hypodense areas within the stent. A ISAR>2 was an accurate criteria (2 false positives, 0 false negative) for detection of significant (> 50%) intra-stent restenosis.
Conclusion: high resolution 64-slice CT allows reliable in-stent visualization for stents of 3 mm or more in diameter, if heart rate is below 65 bpm. Significant restenosis can be detected with a high sensitivity by determining the ISAR. Arch Mal