Rationale and Objectives
To evaluate reconstruction image quality at the systolic and diastolic cardiac phases and determine the optimal phase for reconstruction according to heart rate when using dual-source computed tomography (CT) with 75 ms temporal resolution.
Materials and Methods
We retrospectively reviewed the CT datasets of 35 patients with regular heartbeats who underwent coronary CT angiography. Images were reconstructed in 2% steps between 32 and 78% of the beat-to-beat interval. Two experienced radiologists determined the reconstruction interval with the fewest motion artifacts and the motion score of each vessel for the systolic and diastolic phases. Subgroup analysis was performed in patients having heart rates of <70, 70–80, and >80 beats per minute (bpm).
Results
In the subgroup with heart rates of <70 bpm, the diastolic phase reconstruction image quality was significantly better than for the systolic phase ( P < .01). In the 70–80 bpm and >80 bpm subgroups, no significant difference was observed. In the diastolic phase, the image quality of the <70 bpm subgroup was significantly better than for the >80 bpm subgroup ( P < .05). In all systolic phase subgroups and other diastolic phase subgroups, no significant difference was observed.
Conclusions
Using a DSCT scanner with 75 ms temporal resolution, reconstruction at the diastolic phases should be used for patients with heart rates <70 bpm. For heart rates >70 bpm, larger studies are necessary to determine whether reconstruction at the systolic, diastolic, or both phases should be used.
Recently, cardiac computed tomography (CT) has found widespread acceptance as a noninvasive imaging tool for the evaluation of coronary heart disease. In the past, the retrospective electrocardiogram (ECG)-gated helical scanning technique was usually used for coronary CT angiography (CTA) . However, in recent years the prospective ECG-gated scanning technique has found increased use thanks to developments in CT technology, leading to a reduction in radiation exposure . Furthermore, motion artifacts have been reduced through improved reconstruction techniques and improved temporal resolution made possible by faster gantry rotation speeds.
The recently introduced dual-source CT (DSCT) scanner is fitted with two sets of image acquisition systems (consisting of an x-ray tube and detector) arranged relative to each other at an angle of approximately 90°. Thus, if data from both detectors are combined, an almost 90° rotation of the gantry is sufficient to acquire the 180° projection data needed for image reconstruction. Moreover, the effective gantry rotation speed is increased. With these developments, the achievable temporal resolution using a half-scan reconstruction technique is as low as 75 ms in currently available systems and remains constant at all heart rates.
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Materials and methods
Patients, Scan Protocol, Image Reconstruction
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Image Analysis
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Estimation of Radiation Dose
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Statistical Analysis
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Results
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Table 1
The Position of the Optimal Reconstruction Window for Each Segment in Both the Systolic and Diastolic Phases
Coronary Vessel Vessel Number Systolic Phase (%) Diastolic Phase (%) Mean ± SD Mean ± SD RCA #1 39.9 ± 4.6 72.6 ± 2.5 #2 39.7 ± 5.2 73.3 ± 3.0 LAD #7 34.9 ± 2.5 70.7 ± 2.1 #8 34.9 ± 3.0 70.7 ± 2.1 LCx #11 36.3 ± 3.1 71.3 ± 2.8 #13 35.6 ± 3.2 71.4 ± 2.3
LAD, left anterior descending; LCx, left anterior circumflex artery; RCA, right coronary artery; SD, standard deviation.
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Differences in Image Quality between the Systolic and the Diastolic Phases for Each Subgroup
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Table 2
Differences in Image Quality between the Systolic and the Diastolic Phase by Subgroup
Systolic Phase Diastolic Phase Motion Score Motion Score RCA HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 2 16 1 1 15 5 0 0P < .01 70–80 ( n = 9) 2 6 1 0 4 4 0 1 NS >80 ( n = 5) 0 5 0 0 0 2 1 2 NS LAD HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 4 15 1 1 17 3 0 0P < .01 70–80 ( n = 9) 2 6 1 0 4 5 0 0 NS >80 ( n = 6) 1 5 0 0 2 4 0 0 NS LCx HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 9 10 1 0 19 1 0 0P < .01 70–80 ( n = 9) 4 5 0 0 6 2 1 0 NS >80 ( n = 6) 0 6 0 0 2 3 1 0 NS
HR, heart rate; LAD, left anterior descending; LCx, left anterior circumflex artery; NS, not significant; RCA, right coronary artery.
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Difference in Image Quality between Subgroups for the Systolic and the Diastolic Phases
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Table 3
Differences in Image Quality between Subgroups in the Systolic and the Diastolic Phase
Systolic Phase Diastolic Phase RCA HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 2 16 1 1
15 5 0 0
70–80 ( n = 9) 2 6 1 0 4 4 0 1 >80 ( n = 5) 0 5 0 0 0 2 1 2 LAD HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 4 15 1 1
17 3 0 0
70–80 ( n = 9) 2 6 1 0 4 5 0 0 >80 ( n = 6) 1 5 0 0 2 4 0 0 LCx HR 4 3 2 1 4 3 2 1 <70 ( n = 20) 9 10 1 0 19 1 0 0 70–80 ( n = 9) 4 5 0 0 6 2 1 0 >80 ( n = 6) 0 6 0 0 2 3 1 0
HR, heart rate; LAD, left anterior descending; LCx, left anterior circumflex artery; NS, not significant; RCA, right coronary artery.
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Discussion
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Limitations
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Conclusion
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References
1. Budoff M.J., Achenbach S., Blumenthal R.S., et. al.: Assessment of coronary artery disease by cardiac computed tomography: a scientific statement from the American Heart Association Committee on Cardiovascular Imaging and Intervention, Council on Cardiovascular Radiology and Intervention, and Committee on Cardiac Imaging, Council on Clinical Cardiology. Circulation 2006; 114: pp. 1761-1791.
2. Bischoff B., Hein F., Meyer T., et. al.: Comparison of sequential and helical scanning for radiation dose and image quality: results of the Prospective Multicenter Study on Radiation Dose Estimates of Cardiac CT Angiography (PROTECTION) I Study. AJR Am J Roentgenol 2010; 194: pp. 1495-1499.
3. Hirai N., Horiguchi J., Fujioka C., et. al.: Prospective versus retrospective ECG-gated 64-detector coronary CT angiography: assessment of image quality, stenosis, and radiation dose. Radiology 2008; 248: pp. 424-430.
4. Shuman W.P., Branch K.R., May J.M., et. al.: Prospective versus retrospective ECG gating for 64-detector CT of the coronary arteries: comparison of image quality and patient radiation dose. Radiology 2008; 248: pp. 431-437.
5. Herzog C., Arning-Erb M., Zangos S., et. al.: Multi-detector row CT coronary angiography: influence of reconstruction technique and heart rate on image quality. Radiology 2006; 238: pp. 75-86.
6. Leschka S., Husmann L., Desbiolles L.M., et. al.: Optimal image reconstruction intervals for non-invasive coronary angiography with 64-slice CT. Eur Radiol 2006; 16: pp. 1964-1972.
7. Seifarth H., Wienbeck S., Püsken M., et. al.: Optimal systolic and diastolic reconstruction windows for coronary CT angiography using dual-source CT. AJR Am J Roentgenol 2007; 189: pp. 1324-1325.
8. International Commission on Radiological Protection (ICRP): 2007 recommendations of the international commission on radiological protection (publication 102). Ann ICRP 2007; 37: pp. 73-79.
9. Araoz P.A., Kirsch J., Primak A.N., et. al.: Optimal image reconstruction phase at low and high heart rates in dual-source CT coronary angiography. Int J Cardiovasc Imaging 2009; 25: pp. 837-845.
10. Weustink A.C., Mollet N.R., Pugliese F., et. al.: Optimal electrocardiographic pulsing windows and heart rate: effect on image quality and radiation exposure at dual-source coronary CT angiography. Radiology 2008; 248: pp. 792-798.
11. Husmann L., Leschka S., Desbiolles L., et. al.: Coronary artery motion and cardiac phases: dependency on heart rate–implications for CT image reconstruction. Radiology 2007; 245: pp. 567-576.
12. Baumüller S., Leschka S., Desbiolles L., et. al.: Dual-source versus 64-section CT coronary angiography at lower heart rates: comparison of accuracy and radiation dose. Radiology 2009; 253: pp. 56-64.
13. Lu B., Mao S.S., Zhuang N., et. al.: Coronary artery motion during the cardiac cycle and optimal ECG triggering for coronary artery imaging. Invest Radiol 2001; 36: pp. 250-256.
14. Braunwald E., Sarnoff S.J., Stainsby W.N.: Determinants of duration and mean rate of ventricular ejection. Circ Res 1958; 6: pp. 319-325.
15. Fridericia L.S.: The duration of systole in an electro cardiogram in normal humans and in patients with heart disease. 1920. Ann Noninvasive Electrocardiol 2003; 8: pp. 343-351.
16. Chung C.S., Karamanoglu M., Kovacs S.J.: Duration of diastole and its phases as a function of heart rate during supine bicycle exercise. Am J Physiol Heart Circ Physiol 2004; 287: pp. H2003-H2008.