Minimally invasive evaluation of coronary stents with electron beam computed tomography: In vivo and in vitro experience

We sought to describe the value of electron beam computed tomography (EBCT) to detect stent restenoses at follow-up and to identify characteristic EBC T features of coronary stents. Six coronary stents (GRII, Jostent, NIR, PS, Micro, Wiktor) were scanned in vitro (10 1.5-mm-thick slices, 15-cm FoV, 1 00-ms AT) before and after inflation with 3.0-, 3.5-, and 4.0 mm balloons t o study intensity values and different stent dimensions in comparison to ca liper measurements, In 44 patients (60 +/- 10 years, 4 females) we prospect ively compared EBCT findings [eight 8-mm-thick slices in the flow mode, 26- cm field of view (FoV), 50 ms acquisition time (AT)] with 6-month angiograp hic outcome after placement of 86 stents in 49 vessels. Far the detection o f significant angiographic luminal narrowing (greater than or equal to 75%) that occurred in 17/49 vessels (35%), we found a sensitivity of 65%, a spe cificity of 84%, and a positive and negative predictive value of 69% and 82 %, respectively. The in vitro data show significant differences in image in tensity between the stents and a significant gradual decrease in image inte nsity with increasing stent diameters, The mean differences between EBCT an d caliper measurements for the length and diameter were 0.17 +/- 0.18 mm an d -0.32 +/- 0.25mm, respectively. EBCT is currently the only noninvasive te chnique that allows the assessment of stent dimensions and stent geometry, which may prove useful in patients when intravascular ultrasound cannot be performed. Contrast-enhanced EBCT is a promising tool for minimally invasiv e stent patency evaluation at follow-up, especially in patients that are un able to exercise. (C) 1999 Wiley-Liss, Inc.