We strove to evaluate in-stent restenosis of the coronary artery by measuring the in-stent CT attenuation with using 16-multislice CT.

We analyzed the coronary CT angiography, with using 16-slice CT, in 45 stents of 30 patients. The CT attenuation was measured in the lumen of the stented segments and in the lumen of the segment proximal to the stents, and this attenuation was compared with each other. The CT attenuation difference between them was analyzed in relation to the presence of significant in-stent restenosis. Conventional coronary angiography was used as a standard of reference for in-stent restenosis.

12 stents in 12 patients revealed significant restenosis on the conventional coronary angiography. In 6 (50%) of them, the CT attenuation value of the in-stent lumen was lower than that of the proximal segments (373.8 HU vs. 497.1 HU, respectively, p=0.77). In the other 6 stents, a small stent diameter (n=3) and adjacent severe calcification (n=2) accounted for the higher CT attenuation value of the in-stent lumen. In all the stents without significant restenosis, the CT attenuation values of the in-stent lumens were higher than those of their proximal segments.

The measurement of CT attenuation with using 16-slice CT at the in-stent lumen as compared to the attenuation of the proximal segment provides an objective, confident method for the diagnosis of in-stent restenosis.