ORIGINAL PAPER Comparison of image quality of 64-slice multidetector CT coronary CT angiography using automated and manual multiphase methods for the determination of optimal phases for image reconstruction in patients with various mean heart rates Young Jun Cho • Yeon Hyeon Choe • Moo-Sik Lee Received: 26 October 2009 / Accepted: 1 November 2009 / Published online: 18 December 2009 Ó Springer Science+Business Media, B.V. 2009 Abstract This study aimed to compare the effects of the automated and manual methods for determin- ing the optimal phase of image reconstruction with the use of 64-slice coronary CT angiography (CCTA). In 63 patients, the optimal trigger delay was determined using an automated technique (Phas- eXact) and by manual phase selection from the images reconstructed at a 10 ms and 1% increment of the R–R interval. The image quality was evaluated using four-step grading. The mean heart rate in all the patients was 70 ± 10.1 bpm (range: 52–98 bpm). The frequency of obtaining diagnostic quality images was highest with the manual absolute timing method (97.6% of 753 segments), while it was 94.7% with manual relative timing and 91.9% with an automated method. The mean image quality score (1.3 ± 0.2) based on the manual absolute timing was significantly better (P = 0.002, one-way ANOVA; P \ 0.05, Scheffe’s test) than the scores determined with the use of the other two techniques (manual relative timing, 1.4 ± 0.3; automated method, 1.5 ± 0.4). The best quality coronary CT images were obtained using image reconstruction with manual absolute timing for the ECG-trigger delay, while an automated method and manual relative timing provided diag- nostic quality images in most of the segments. Keywords Cone-beam computed tomography Á Coronary vessels Á Diagnostic techniques Á Cardiovascular Introduction The recent technical developments in noninvasive coronary angiography with using 64-slice multidetec- tor row computed tomography (MDCT) have provided improved temporal resolution and better image quality than 16-slice MDCT. However, image artifacts due to cardiac motion are still the major cause of degraded image quality of the coronary artery [1–3]. The image quality obtained with MDCT coronary angiography strongly depends on the choice of the appropriate reconstruction parameters, such as the reconstruction algorithm, the reconstruction technique and placement of the reconstruction interval [4]. Choosing the optimal time point for the reconstruction is crucial for preserving the image quality [1, 5, 6]. Y. J. Cho Department of Radiology, Konyang University School of Medicine, Daejeon, Korea Y. H. Choe (&) Department of Radiology and Cardiovascular Imaging Center, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710, Korea e-mail: yhchoe@skku.edu M.-S. Lee Department of Preventive Medicine, Konyang University School of Medicine, Daejeon, Korea 123 Int J Cardiovasc Imaging (2010) 26:41–52 DOI 10.1007/s10554-009-9536-0