| Part 1 Coronary angiography with 64-slice spiral computed tomography:effect of average heart rate and heart rate variability on image qualityObjective: To evaluate the effect of average heart rate and heart rate variability on image quality with 64-slice spiral computed tomography coronary angiography.Materials and Methods: One hundred and twenty-one patients (77 men, 44 women; age range 34~83 years, mean age 60.03 years±12.41[standard deviation]) with under suspicion or diagnosed coronary atherosclerotic heart disease underwent 64-slice spiral computed tomography coronary angiography with retrospective electrocardiographic gating. There were 69 patients (heart rate≥80 bpm) receivedβ-blockers (Betaloc 50mg) before the scanning about 45 minutes as the foundation treatment measures. The segment reconstruction algorithms were adopted in patients with heart rate lower than 75 beats per minute and the burst-two or burst-four reconstruction algorithms were adopted in patients with heart rate more than 75 beats per minute, the data sets were reconstructed in 5% steps from 30% ~85% of R-R interval. Heart rate variability was calculated as standard deviation from mean heart rate during scanning. Coronary artery segments were defined according to American Heart Association guidelines. Each segment coronary artery in each patients were reconstructed with the best reconstruction interval. Two observers evaluated image quality of each segment coronary artery with a diameter of at least 1.5mm (1= no motion artifacts, 5=not evaluation). Linear regression correlation analysis was performed to compare image quality in each patient with average heart rate and heart rate variability.Results: Mean heart rate was significantly decreased in patients after receivingβ-blockers than that before receivingβ-blockers. Moreover, heart rate variability was significantly decreased in patients receivingβ-blockers than that not receivingβ-blockers. Diagnostic image quality (score≤3) was attained in 1739 of 1805 segments(96.35%) at the best reconstruction interval. There was correlation between average heart rate and image quality for all segments of coronary artery(r=0.53, P<0.001). Heart rate variability was also correlation with the image quality overall (r=0.33, P<0.001). There was no correlation between average heart rate or heart rate variability and image quality for the left main coroanry artery, but there was correlation for the left anterior descending artery, the left circumflex artery and the right coronary artery, especially for the left circumflex artery and the right coronary artery.Conclusions: Heart rate and heart rate variability have direct influence on the image quality of the 64-slice spiral computed tomography coronary angiography. To obtain the diagnostic image quality of the coronary artery, heart rate and heart rate variability would be reduced.β-blockers medication administered for the patients who the heart rate is more than 80 beats per minute and (or) the fluctuation amplitude of the heart rate is morer before CT scanning which can lower and stabilize the heart rate through the scanning. Part 2 Diagnostic accuracy on coronary atherosclerotic stenosis by applying 64-slice spiral computed tomography coronary angiography:a preliminary studyObjective: To evaluate the diagnostic accuracy of 64-slice spiral computed tomography coronary angiography on the coronary atherosclerotic stenosis.Materials and Methods: Twenty-one patients (men 11, women 10; age range 50~79 years, mean age 65.05 years±9.95[standard deviation]) with under suspicion coronary atherosclerotic heart disease which with atypical chest pain, stable or unstable angina pectoris, or non-ST-segment elevation myocardial infraction underwent 64-slice spiral computed tomography coronary angiography(CTA) and conventional coronary angiography(CAG).CAG were performed during 3-25 days after CTA done. Patients who with initial heart rate more than 80 beats per minute receivedβ-blockers (Betaloc 50mg) to lower and stabilize the heart rate. There were 84 branches of coronary artery in 21 patients with a differentiation of RCA,LM,LAD and LCX. According to the degree of stenosis, these coronary arteries were devided into two groups: lumen narrowing≥50% and lumen narrowing <50%, using the CAG as a"golden standard", the sensitivity, specificity, positive predictive value and negative predictive value of the CTA for diagnosing the stenosis were analyzed respectively. Results: The sensitivity and the specificity with the 64-slice spiral computed tomography coronary angiography in detecting coronary artery stenoses lumen narrowing≥50% were 96.88%(31/32) and 96.15%(50/52) respectively, the positive predictive value and the negative predictive value were 93.94%(31/33) and 98.04% (50/51) respectively. And the sensitivity and the specificity in detecting coronary artery stenoses lumen narrowing <50% were 75.00%(12/16) and 97.06% (66/68) respectively, the positive predictive value and the negative predictive value were 85.71% (12/14) and 94.29% (66/70) respectively.Conclusions: 64-slice computed tomography coronary angiography could provide a very high diagnostic accuracy in assessing coronary artery stenosis. So it can be considered as the first inspection technique of diagnosing or follow-up coronary atherosclerotic heart disease.
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