Detection of in-stent restenosis of coronary stents using 40-detector row computed tomography in vitro

To evaluate the performance of 40-detector row computed tomography (CT) in the detection of in-stent stenosis of coronary stents.

Seven patent vascular models, 7 stenotic models, and 7 obstructed models were scanned with a 40-detector CT. We made the vascular models using 3 types of stent (Bx-Velocity, Express2, Driver) with an inner diameter of about 2.5, 3.0, or 3.5 mm. We measured the stent lumen diameter and evaluated the in-stent stenosis visually for the 21 vascular models. We evaluated attenuation values of the stent lumen of the 9 patent models of 2.5-mm diameter.

The inner diameters of the vascular models were underestimated by CT with mean measurement errors of -1.19 to -1.49 mm. The absolute mean overall measurement error decreased as the inner diameter increased. The direct visualization of in-stent stenosis was possible for the 3.0- and 3.5-mm diameter models, but impossible for the 2.5-mm diameter models. For patent vascular models of 2.5-mm diameter, the CT attenuation inside the stent was significantly higher than that of the unstented portion (P < 0.0001). For obstructed vascular models of 2.5-mm diameter, the CT attenuation inside the stent was significantly lower than that of the unstented portion (P < 0.0001). Also for stenotic vascular models of 2.5-mm diameter, the CT attenuation inside the stent was lower than that of the unstented portion.

Visualization of stent lumen on CT is affected by the stent diameter. Measurement of stent lumen is useful for detection of in-stent stenosis, when the direct visualization of in-stent stenosis is impossible.