Ability of calibration phantom to reduce the interscan variability in electron beam computed tomography

• Published in: Journal of computer assisted tomography Vol. 26; no. 6; pp. 886 - 891
• Main Authors: BUDOFF, Matthew J, SONGSHOU MAO, BIN LU, TAKASU, Junichiro, CHILD, Janis, CARSON, Sivi, FISHER, Hans
• Format: Journal Article
• Language: English
• Published: Hagerstown, MD Lippincott 01-11-2002
• Subjects: Biological and medical sciences; Calcinosis - diagnostic imaging; Calcium - analysis; Calibration; Cardiology. Vascular system; Cardiomyopathies - diagnostic imaging; Cardiovascular system; Coronary heart disease; Coronary Vessels - chemistry; Heart; Humans; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Radiodiagnosis. Nmr imagery. Nmr spectrometry; Reproducibility of Results; Tomography, X-Ray Computed - methods; Tomography, X-Ray Computed - standards; Human; Computed tomography-Electron beam-Coronary artery calcification-Reproducibility-Calibration phantom; Radiodiagnosis; Calcium; Coronary artery; Cardiovascular disease; Coronary arteriography; Vascular disease; Image quality; Reproducibility; Measurement technique; Atherosclerosis; Calipering; Interindividual comparison; Medical imagery; Computerized axial tomography; Test object
• ISSN: 0363-8715; 1532-3145
• DOI: 10.1097/00004728-200211000-00005

To test the hypothesis that a calibration phantom would improve interpatient and interscan variability in coronary artery calcium (CAC) studies.
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.
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.
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.