The influence of reconstruction algorithm and heart rate on coronary artery image quality and stenosis detection at 64-detector cardiac CT.
OBJECTIVE
We wanted to evaluate the impact of two reconstruction algorithms (halfscan and multisector) on the image quality and the accuracy of measuring the severity of coronary stenoses by using a pulsating cardiac phantom with different heart rates (HRs).


METHODS
Simulated coronary arteries with different stenotic severities (25, 50, 75%) and different luminal diameters (3, 4, 5 mm) were scanned with a fixed pitch of 0.16 and a 0.35 second gantry rotation time on a 64-slice multidetector CT. Both reconstruction algorithms (halfscan and multisector) were applied to HRs of 40-120 beats per minute (bpm) at 10 bpm intervals. Three experienced radiologists visually assessed the image quality and they manually measured the stenotic severity.


RESULTS
Fewer measurement errors occurred with multisector reconstruction (p = 0.05), a slower HR (p < 0.001) and a larger luminal diameter (p = 0.014); measurement errors were not related with the observers or the stenotic severity. There was no significant difference in measurements as for the reconstruction algorithms below an HR of 70 bpm. More nonassessable segments were visualized with halfscan reconstruction (p = 0.004) and higher HRs (p < 0.001). Halfscan reconstruction had better quality scores when the HR was below 60 bpm, while multisector reconstruction had better quality scores when the HR was above 90 bpm. For the HRs between 60 and 90 bpm, both reconstruction modes had similar quality scores. With excluding the nonassessable segments, both reconstruction algorithms achieved a similar mean measured stenotic severity and similar standard deviations.


CONCLUSIONS
At a higher HR (above 90 bpm), multisector reconstruction had better temporal resolution, fewer nonassessable segments, better quality scores and better accuracy of measuring the stenotic severity in this phantom study.
Department of Medical Imaging, National Taiwan University Hospital, Taipei, Taiwan.
Yi-Ting
YT
Wang
Chung-Yi
CY
Yang
Jong-Kai
JK
Hsiao
Hon-Man
HM
Liu
Wen-Jen
WJ
Lee
Yun
Y
Shen
D000465:Algorithms; D016477:Artifacts; D003198:Computer Simulation; D017023:Coronary Angiography / Q000379:methods*; D023921:Coronary Stenosis / Q000000981:diagnostic imaging*; D004562:Electrocardiography; D006339:Heart Rate; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D008955:Models, Cardiovascular; D015588:Observer Variation; D019047:Phantoms, Imaging; D015203:Reproducibility of Results; D012720:Severity of Illness Index; D036542:Tomography, Spiral Computed / Q000379:methods*