Ability of calibration phantom to reduce the interscan variability in electron beam computed tomography.
OBJECTIVE
To test the hypothesis that a calibration phantom would improve interpatient and interscan variability in coronary artery calcium (CAC) studies.


METHODS
We scanned 144 patients twice with or without the calibration phantom and then scanned 93 patients with a single calcific lesion twice and, finally, scanned a cork heart with calcific foci.


RESULTS
There were no linear correlations in computed tomography Hounsfield unit (CT HU) and CT HU interscan variation between blood pool and phantom plugs at any slice level in patient groups (p > 0.05). The CT HU interscan variation in phantom plugs (2.11 HU) was less than that of the blood pool (3.47 HU; p < 0.05) and CAC lesion (20.39; p < 0.001). Comparing images with and without a calibration phantom, there was a significant decrease in CT HU as well as an increase in noise and peak values in patient studies and the cork phantom study.


CONCLUSIONS
The CT HU attenuation variations of the interpatient and interscan blood pool, calibration phantom plug, and cork coronary arteries were not parallel. Therefore, the ability to adjust the CT HU variation of calcific lesions by a calibration phantom is problematic and may worsen the problem.
Budoff
Matthew J
MJ
Department of Medicine, Division of Cardiology, Harbor-UCLA Research and Education Institute, 1124 W. Carson Street RB-2, Torrance, CA 90502, USA. budoff@flash.net
Mao
Songshou
S
Lu
Bin
B
Takasu
Junichiro
J
Child
Janis
J
Carson
Sivi
S
Fisher
Hans
H
D016477:Artifacts; D002114:Calcinosis / Q000000981:diagnostic imaging; D002118:Calcium / Q000032:analysis*; D002138:Calibration; D009202:Cardiomyopathies / Q000000981:diagnostic imaging*; D003331:Coronary Vessels / Q000737:chemistry*; D006801:Humans; D015203:Reproducibility of Results; D014057:Tomography, X-Ray Computed / Q000379:methods* / Q000592:standards
D002118:Calcium