利用β阻斷劑提昇冠狀動脈電腦斷層影像品質之探討

Advancement of Image Quality with β- Blocker in Coronary Artery Computer Tomography

多列式電腦斷層發展過程都受限於心跳頻率，因此常須透過β阻斷劑來降低心跳頻率。所以本研究探討β阻斷劑使用在64列電腦斷層中影像品質上的效益。從2007年11月到2008年12月總共收集100名接受冠狀動脈電腦斷層攝影的健康檢查的受檢者，檢查時心跳頻率必需低於每分鐘80跳。其全部受檢者掃描過程的平均心跳頻率為67.2±5.6跳。重組一次影像就能診斷的心跳頻率為65.0±4.9跳，而需要藉由重組二次影像才能診斷的心跳頻率為71.6±4.1跳，因此低心跳頻率有助於減少重組次數(P<0.05)。有61位受檢者有服用藥物，其中有服用藥物的人需重組一次的比率為76%；沒有服用藥物的人需重組二次的比率為56%，所以服用藥物只需重組一次的頻率較高。並且在重組二次的受檢者中，有服用藥物(74.1±3.0)較沒有服藥(70.3±4.0)的心跳頻率高(P<0.05)。由於心跳頻率的增加，重組二次的機率相對增加，而降低影像品質。β阻斷劑雖不但具有降低心跳速率的功用，更擁有穩定心跳頻率的效用，使得在掃描過程中減少心跳頻率的波動，將大幅提高冠狀動脈電腦斷層的影像品質。

Heart rate is the main factor in the development of multidetector-row computed tomography (CT), and taking β-blockers decreases average heart rate. The purpose of this study was to explore whether taking β-blockers improves image quality in patients undergoing coronary artery CT. A total of 100 patients with heart rates of less than 80 beats per minute underwent coronary artery CT as part of physical examination. During scanning, the average heart rate was 67.2 ± 5.6 beats per minute. A heart rate of 65.0 ± 4.9 beats per minute was associated with single reconstruction, and a heart rate of 71.6 ± 4.1 beats per minute was associated with double reconstruction. Thus, a lower heart rate is associated with reduced reconstruction frequency (P < 0.05). Of the 100 patients, 61 had taken β-blockers. The rate of single reconstruction of patients receiving β-blockers was 76%; the rate of double reconstruction of patients not receiving β-blockers was 56%. Thus, the frequency of single reconstruction among patients receiving β-blockers was high. Among patients with double reconstruction, the average heart rate of patients receiving β-blockers (74.1 ± 3.0 beats per minute) was higher than that of patients not receiving β-blockers (70.3 ± 4.0 beats per minute) (P < 0.05). The heart rate increased along with the probability of double reconstruction. The receipt of β-blockers reduces average heart rate and heart rate variability and thus improves the image quality of coronary artery CT.