Evaluation Of Coronary In-Stent Restenosis With 64-Slice Computed Tomography

Objectives:This study sought to evaluate the diagnostic accuracy of coronary in-stent restenosis (ISR) with angiography using 64-slice multislice computed tomography coronary angiography (CTCA) compared with conventional coronary angiography. (CAG) and analyze the influencing factors such as the stent diameter, strut thickness and heart rate during MSCT data acquisition on imaging quality.Methods:From January 2008 to December 2010,64 slice computed tomography coronary angiography was performed on 90 patients with previous coronary stent implantation (75 men,15 women,age ranged from 34 to 78 years old, mean age, 59±10 years old). Exclusion criteria were the following:1) atrial fibrillation,2) renal insufficiency (serum creatinine level> 120 mmol/L) and 3) known allergy to iodinated contrast media.All examinations were performed with the 64-slice Philips Brilliance CT scanner with dedicated cardiac reconstruction software. The scan volume was determined from the carina to the diaphragmatic surface of the heart.Intravenous non-ionic contrast agent (Ultravist 370),70ml, was injected at a rate of 5 ml/sec followed by saline flush to the antecubital vein using a dualhead automatic injector. Two experienced CT radiologists, both blinded to angiographic and clinical findings but aware of previous cardiac history, evaluated the MSCT examinations using axial slices and multiplanar and curved reconstructions.Conventional selective coronary angiography was performed with standard techniques and evaluated by two reviewers blinded to the MSCT results. An in-stent luminal diameter that was narrowed by 50% or more (up to in-stent occlusion) was defined as significant restenosis. Sensitivity, specificity, positive and negative predictive values for the detection of in-stent restenosis≥50% using conventional angiography in combination with quantitative coronary angiography as the gold standard, were calculated. A value of p<0.05 was considered statistically significant.Results:A total of 11 (7.5%) stented segments were excluded because of poor image quality. In the interpretable stents,13 of the 142 (9.2%) evaluated stents were significantly diseased, of which 12 were correctly detected by 64-slice MSCT. Accordingly, sensitivity, specificity, and positive and negative predictive value to identify in-stent restenosis in interpretable stents were 92.3%,93.8%,60.0%,99.2%, respectively. The mean diameter of interpretable stents was 3.1±0.4 mm, whereas the mean diameter of uninterpretable stents was 2.8±0.3 mm(P=0.023). In interpretable stents, average heart rate during MSCT data acquisition was 61.5±5.6 beats/min, but the average heart rate was 66.3±3.9 beats/min in uninterpretable stents (P=0.002) There were 37(26%) stents with struts with 0.14mm thick or thicker in interpretable stents however 7(63.6%) stents in uninterpretable stents (P=0.021).Conclusion:In-stent restenosis can be evaluated with 64-slice MSCT with good diagnostic accuracy. In particular, a high negative predictive value of 99.2% was observed, indicating that 64-slice MSCT may be most valuable as a noninvasive method of excluding in-stent restenosis. The stent diameter strut thickness and heart rate during MSCT data acquisition influence interpretability concerning in-stent restenosis by MSCT.