| Objective Catheter ablation is an effective and safe treatment method for the patients with refractory atrial fibrillation. However, variations in left atrium and pulmonary vein anatomy bring challenge to electrophysiologists. MDCT scanner are preferable to evaluate the cardiac anatomy preoperatively because of their improved spatial and temporal resolution and coverage. They offer advantages of reduced scanning time, motion artifacts, contrast medium requirement and radiation dose and improved image quality. Additional, MDCT can be integrated with EAM system and reduce the fluroscopic time and improve outcomes, which is most important for the electrophysiologist. This study was designed to evaluate left atrium anatomical abnormalities and to establish the pulmonary morphology, ostial diameter, ostial orientation and distance from ostium to first bifurcation by 256-slice CT.Material and Methods 102 patients (46 males and 56 females) undergoing 256-slice CT scans (Brilliance iCT, Philips) to exclude coronary artery disease were enrolled. All patients underwent a retrospectively ECG-gated cardiac CT examination using 256-slice CT technology. The scan parameters were as follows:tube voltage, 100 kV; effective tube current-time product,700 mAs; pitch,0.18; detector collimation,128 ×0.625 mm; rotation time,270 ms; slice thickness,0.9 mm; and increment,0.6 mm. Automatic bolus tracking (Bolus Pro, Philips Healthcare) was used. Raw spiral CT data were reconstructed at 75% of the R-R interval, postprocessed, and analyzed on a dedicated workstation (IntelliSpace Portal). Left atrium anatomical abnormalities, pulmonary veins morphology, ostial diameter, ostial orientation, and distance from ostium to first bifurcation were evaluated using 3-dimensional volume-rendering and multiplana reformatting technology. Statistical analysis was performed using commercially available software (SPSS, version 17.0 for Windows).Results (1) The prevalence and mean length and width for diverticula were 20.5%, 7.1 mm, and 7.0 mm and for accessory appendages 6.9%,6.9 mm, and 5.3 mm, respectively. The most common location for a diverticulum or an accessory appendage was the right anterior wall of left atrium.(2) 72.5% of patients had conventional four pulmonary veins. On the right, 22.5% of patients had one accessory pulmonary vein,0.05% had 2 accessory pulmonary veins,0.01% had 1 common pulmonary vein,0.01% had 1 top vein. On the left,27.5% of patients had 1 common pulmonary vein.9.8% of patients had bilateral pulmonary vein variation.(3) The ostial size was larger for superior pulmonary veins than for inferior pulmonary veins, and larger for right pulmonary veins than for left pulmonary veins; pulmonary vein ostia on the right tended to be more circular.(4) There was a rather wide interindividual range of projective angle.(5) There was a rather wide interindividual range of distance from ostium to first bifurcation. The distance from ostium to first bifurcation of left superior pulmonary vein was larger, The distance from ostium to first bifurcation of right inferior pulmonary vein was shorter. Early branching occurred more often in right inferior pulmonary vein..Conclusion 256-slice CT can depict laft atrium and pulmonary vein anatomy and afford substantial data, which may be of great help for electrophysiologists to select proper catheters, adjust proper radiofrequency energy, avoid postoperative complications and fulfil the catheter ablation procedure as soon as possible.Objective Catheter ablation is an effective and safe treatment for patients with paroxysmal and persistent atrial fibrillation. Detailed knowledge of left atrium (LA) and pulmonary veins (PVs) anatomy before catheter ablation is required for the safety and efficacy of this procedure, particularly when using advanced mapping techniques. However, the growing frequency of CT scanning has been associated with greater radiation exposure to patients. This study aims to compare the image quality and effective radiation dose (ED) of prospectively gated transaxial (PGT) with retrospectively gated helical (RGH) CT for LA and PVs imaging using low-dose 256-slice CT, and to evaluate the feasibility of low-dose PGT 256-slice CT technique for LA and PVs imaging.Material and Methods From January,2014 to December,2014,48 patients (34 male,14 female, mean age:55.4 ± 9.0) underwent cardiac CT obtained with 100 kV PGT technique for the exclusion of coronary artery disease on a 256-slice CT scanner. For each PGT patient, we found the paired ones in RGH patient database. The selection criteria for matching were gender (consistent), age (within 2 years), BMI (within 5%), heart rate (within 2%) and heart rate variability (within 3%). The image quality (good, moderate and poor) was evaluated by two reviewers. The CT-attenuation, image noise and contrast to noise ratio of LA and main PVs were evaluated, respectively. Volume CT dose index, dose length product and the effective dose between the two scan groups were evaluated. Statistical analysis was performed using commercially available software (SPSS, version 17.0 for Windows).Results In the PGT group, the image quality was good in 41 cases (85.4%) and moderate in 7 cases (14.6%). In the RGH group, the image quality was good in 46 cases (95.8%) and moderate in 2 cases (4.2%). No poor (non-diagnostic) image quality was found in both groups. There were no significant differences in subjective image quality between the two groups (P=0.161). In the PGT group, the mean absolute CT-attenuation, mean image noise and mean contrast-to-noise ratio of LA was 511.1±84.0 HU,50.0±9.7 HU and 13.6±6.0. In the RGH group, the mean absolute CT-attenuation, mean image noise and mean contrast-to-noise ratio of LA was 486.8±115.8HU,47.5±6.0 HU and 12.6±2.6. There were no statistical differences in the CT-attenuation, image noise and contrast-to-noise ratio for LA and PVs between the two groups (P>0.05). There were significant differences in the Volume CT dose index, dose length product and the effective dose between the two groups (P<0.001). The mean estimated effective radiation dose of the PGT group was 3.3 ± 0.3 mSv, reflecting a reduction of 56.6% compared to the RGT scans (7.6 ±0.8 mSv).Conclusion low-dose PGT 256-slice CT for LA and PVs imaging can provide consistent image quality comparable to the traditional RGH technique while also offering significant reduction in ED. |
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