Department of Medical Imaging, Jinan Military General Hospital, Jinan, Shangdong Province, China.
Br J Radiol. 2012 Aug;85(1016):e388-94. doi: 10.1259/bjr/92160185. Epub 2012 Feb 28.
To evaluate the effects of heart rate and heart rate variability on image quality, patient dose and diagnostic accuracy of 320-detector row CT.
94 patients were prospectively enrolled. Heart rate was defined as the mean value of different intervals elapsing between two consecutive R waves in an electrocardiogram (R-R intervals) and the heart rate variability was calculated as the standard deviation from the average heart rate. The image quality was evaluated by four grades, according to motion artefacts ("step artefacts" and "blurring artefacts"). The diagnostic accuracy was analysed in 43 patients who were scheduled for invasive coronary angiography (ICA). The coeffects of heart rate and heart rate variability on image quality, radiation dose and diagnostic accuracy were evaluated by multivariate regression.
The mean image quality score was 1.2 ± 0.5 and the mean effective dose was 14.8 ± 9.8 mSv. The results showed that heart rate (74.0 ± 11.2 beats per minute) was the single factor influencing image quality (p<0.001) and radiation dose (p<0.001), while heart rate variability (3.7 ± 4.6) had no significant effect on them (p=0.16 and p=0.47, respectively). For 43 patients who underwent ICA, heart rate and heart rate variability showed no influence on the accuracy (p=0.17 and p=0.12, respectively). Overall sensitivity was 97.4% (37/38), specificity was 99.4% (351/353), positive predictive value was 94.9% (37/39) and negative predictive value was 99.7% (351/352).
320-detector row CT, with improved longitudinal coverage of detector, resolves step artefact and high patient dose caused by irregular heart rate. However, it is still recommended to control heart rate to a lower level to eliminate blurring artefact and radiation dose.
评估心率和心率变异性对 320 排 CT 图像质量、患者剂量和诊断准确性的影响。
前瞻性纳入 94 例患者。心率定义为心电图中两个相邻 R 波之间的平均时间间隔（R-R 间期），心率变异性计算为平均心率的标准差。根据运动伪影（“阶梯伪影”和“模糊伪影”）将图像质量评为 4 级。对 43 例行有创冠状动脉造影（ICA）的患者进行诊断准确性分析。采用多元回归评估心率和心率变异性对图像质量、辐射剂量和诊断准确性的协同影响。
平均图像质量评分为 1.2±0.5，有效剂量为 14.8±9.8 mSv。结果显示，心率（74.0±11.2 次/分钟）是影响图像质量（p＜0.001）和辐射剂量（p＜0.001）的单一因素，而心率变异性（3.7±4.6）对两者均无显著影响（p=0.16 和 p=0.47）。对于 43 例行 ICA 的患者，心率和心率变异性对准确性无影响（p=0.17 和 p=0.12）。总体敏感性为 97.4%（37/38），特异性为 99.4%（351/353），阳性预测值为 94.9%（37/39），阴性预测值为 99.7%（351/352）。
320 排 CT 探测器纵向覆盖范围的改善可解决因不规则心率引起的阶梯伪影和高患者剂量问题。但仍建议控制心率处于较低水平，以消除模糊伪影和辐射剂量。
