Coronary In-Stent Restenosis: Assessment with CT Coronary Angiography

Purpose: To compare accuracy and radiation exposure of a new computed tomographic (CT) scanner with improved spatial resolution (scanner A) with those of a CT scanner with standard spatial resolution (scanner B) for evaluation of coronary in-stent restenosis (ISR) by using invasive coronary angiography (ICA) and intravascular ultrasonography (US) as reference methods. Materials and Methods: Written informed consent was obtained and study protocol was approved by institutional ethics committee. A total of 180 consecutive patients (154 men [mean age +/- standard deviation, 66 years +/- 12; range, 51-79 years] and 36 women [mean age, 70 years +/- 12; range, 55-83 years]) scheduled to undergo ICA for suspected ISR were enrolled. Ninety patients were studied with scanner A (group 1: 72 men [mean age, 65 years +/- 11; range, 52-79], 18 women [mean age, 68 years +/- 12; range, 55-83 years]) and 90 with scanner B (group 2: 74 men [mean age, 64 years +/- 10; range, 51-77 years], 16 women [mean age, 68 years +/- 11; range, 55-82 years). Examination with the two scanners was compared with ICA and intravascular US. Radiation dose exposure was estimated. To compare stent evaluability between the two groups, chi(2) test was used. Results: Stent evaluability was higher in group 1 than in group 2 (99% vs 92%, P = .0021). A significantly lower rate of beam-hardening artifact was observed in group 1 (two cases) than group 2 (12 cases, P < .05). For stent-based analysis, sensitivity, specificity, and accuracy of multidetector CT for ISR identification were 96%, 95%, and 96% in group 1 and 90%, 91%, and 91% in group 2, respectively, without statistically significant differences. The correlation between percent ISR evaluated at multidetector CT versus intravascular US was higher in group 1 than in group 2 (r = 0.89 vs r = 0.58; P = .019). The correlations of diameter and area measurements at reference site and stent maximal lumen narrowing site between multidetector CT and intravascular US were higher in group 1 than in group 2. Radiation dose was low in both multidetector CT groups (1.9 mSv +/- 0.2). Conclusion: Scanner A, with improved spatial resolution, allowed reliable detection and quantification of coronary ISR with low radiation exposure.