RESUMO
Objective To evaluate the image quality of coronary CT angiography (CTA) and the diagnostic accuracy for the assessment of coronary artery stenosis with a 64-slice CT scanner.Methods 120 patients with suspected coronary artery disease were studied by ECG-gated 64-slice spiral CT (120 kV, 850 mAs,0.33 s-rotation time,0.6 mm collimation);60 of them also underwent conventional coronary angiography(CCA).Patients with heart rates above 70 bpm received oral?-blockade before the scan. Enhanced scan was performed with an intravenous injection of 60-70 ml contrast agent (370 mg l/ml) and 50 ml saline chaser bolus at 4 ml/s.Images were retrospectively reconstructed under different reformations multiplanar reconstruse-tion(MPR),maximum intensity projection(MIP)and volume rendering technology (VRT)and reviewed by two observers.Image quality was assessed using a 3-point grading scale(excellent, sufficient and non-diagnostic)and the visibility of coronary branches was evaluated.The left main,left anterior descending,left circumflex and right coronary arteries were screened for the presence of over 50% stenosis.Results Sixty-nine percent of the included patients received?-bloekade.The average heart rate was 61?8 bpm and the scan time was 11.9?1.3 s.In the evaluation of image quality with VRT images, 77% patients′images were excellent,18% sufficient,and 5% non-diagnostic.All of the first,most of the second and third,and parts of the fourth subsegment branches could be shown with MPR,MIP and VRT reconstruction images.MPR and MIP displayed better visualization than VRT in showing small branches. Compared with CCA,the sensitivity,specificity,positive and negative predictive value of CTA to identify over 50% stenosis were 93%,98%,87% and 99%,respectively.Conclusion 64-slice spiral CT coronary angiography is a noninvasive and fast method that allows reliable diagnosis of coronary artery stenosis with high image quality.