Anders Katharina, Baum Ulrich, Schmid Michael, Ropers Dieter, Schmid Axel, Pohle Karsten, Daniel Werner G, Bautz Werner, Achenbach Stephan
Department of Radiology, Friedrich-Alexander University of Erlangen-Nuremberg, Germany.
Eur J Radiol. 2006 Mar;57(3):336-44. doi: 10.1016/j.ejrad.2005.12.018. Epub 2006 Jan 30.
To investigate the ability of 16-slice multidetector-row computed tomography (MDCT) to visualize coronary artery bypass graft (CABG) patency and to detect bypass stenoses.
Thirty-two patients with 94 grafts (20 mammary artery grafts, 74 venous grafts) were investigated by 16-slice MDCT using a scan protocol with 12 x 0.75 mm slice collimation (pitch 0.3), 420 ms rotation time and simultaneous electrocardiogram (ECG)-registration. One hundred milliliters iodinated contrast agent were injected with a delay according to the individually determined contrast agent transit time. Patients with heart rates above 60 bpm received oral beta-blockade. Cross-sectional images with a slice width of 1.0 mm (0.5 mm increment) were reconstructed using an ECG-gated half-scan reconstruction or a multisegment reconstruction algorithm depending on the heart rate. Bypass grafts were evaluated concerning patency and presence of stenoses > or = 50% diameter reduction on cross-sectional images, multiplanar reformations and maximum intensity projections by two independent observers. Results were compared to coronary bypass angiography.
Sixteen-slice MDCT results were compared to those of invasive coronary angiography concerning absence or presence of bypass graft occlusion or relevant stenosis > or = 50% lumen reduction. Coronary CT angiography (CTA) permitted detection of bypass occlusion with 100% sensitivity (28/28) and 98% specificity (64/65). Seventy-eight percent (observer 1) and 84% (observer 2) of all patent grafts were found to be evaluable concerning presence or absence of stenosis. In 34 of 40 (observer 1) and 38 of 43 (observer 2) bypass grafts, high-grade stenoses were correctly ruled out (specificity 85% versus 88%, sensitivity 80% and 82%). Yet, if all patients with either unevaluable grafts/graft anastomosis or relevant graft stenosis were excluded, only 8/32 patients (25%) had fully diagnostic "negative" graft-CTA. According to Kappa statistics, agreement between the observers was 1.0 and 0.93 concerning occlusion and relevant stenosis, respectively.
Sixteen-slice coronary CTA with sub-millimeter spatial resolution and premedication with oral beta-blockade permits non-invasive assessment of coronary artery bypass grafts with decreasing numbers of unevaluable graft segments. However, patient-based analysis reveals that only a relatively small number of patients ("negative" and completely evaluable graft-CTA) truly profits from noninvasive work-up and could be spared invasive angiography.
探讨16层多排螺旋计算机断层扫描（MDCT）观察冠状动脉旁路移植术（CABG）血管通畅情况及检测旁路狭窄的能力。
对32例患者的94条移植血管（20条乳内动脉移植血管，74条静脉移植血管）进行16层MDCT检查，扫描方案采用12×0.75mm层厚准直（螺距0.3）、420ms旋转时间并同步记录心电图（ECG）。根据个体确定的造影剂通过时间延迟注入100ml碘化造影剂。心率高于60次/分的患者口服β受体阻滞剂。根据心率，使用ECG门控半扫描重建或多段重建算法重建层厚为1.0mm（增量0.5mm）的横断面图像。由两名独立观察者在横断面图像、多平面重组和最大密度投影上评估旁路移植血管的通畅情况及直径减少≥50%的狭窄情况。将结果与冠状动脉旁路血管造影进行比较。
将16层MDCT结果与有创冠状动脉造影结果进行比较，观察旁路移植血管闭塞或管腔减少≥50%的相关狭窄情况。冠状动脉CT血管造影（CTA）检测旁路闭塞的敏感性为100%（28/28），特异性为98%（64/65）。在所有通畅的移植血管中，观察者1发现78%、观察者2发现84%的血管可评估有无狭窄。观察者1在40条旁路移植血管中的34条、观察者2在43条旁路移植血管中的38条正确排除了高度狭窄（特异性分别为85%和88%，敏感性分别为80%和82%）。然而，如果排除所有移植血管/移植血管吻合不可评估或有相关移植血管狭窄的患者，只有8/32例患者（25%）的移植血管CTA为完全诊断性“阴性”。根据Kappa统计，观察者之间在闭塞和相关狭窄方面的一致性分别为1.0和0.93。
具有亚毫米空间分辨率的16层冠状动脉CTA及口服β受体阻滞剂预处理可对冠状动脉旁路移植血管进行无创评估，不可评估的移植血管段数量减少。然而，基于患者的分析显示，只有相对少数患者（“阴性”且移植血管CTA完全可评估）真正从无创检查中获益，可避免有创血管造影。
