To determine inter-session and intra/inter-individual variations of the attenuations of aortic blood/myocardium with MDCT in the context of calcium scoring. To evaluate whether these variations are dependent on patients' characteristics.Fifty-four volunteers were evaluated with calcium scoring non-enhanced CT. We measured attenuations (inter-individual variation) and standard deviations (SD, intra-individual variation) of the blood in the ascending aorta and of the myocardium of left ventricle. Every volunteer was examined twice to study the inter-session variation. The fat pad thickness at the sternum and noise (SD of air) were measured too. These values were correlated with the measured aortic/ventricular attenuations and their SDs (Pearson). Historically fixed thresholds (90 and 130 HU) were tested against different models based on attenuations of blood/ventricle.The mean attenuation was 46 HU (range, 17-84 HU) with mean SD 23 HU for the blood, and 39 HU (10-82 HU) with mean SD 18 HU for the myocardium. The attenuation/SD of the blood were significantly higher than those of the myocardium (p < 0.01). The inter-session variation was not significant. There was a poor correlation between SD of aortic blood/ventricle with fat thickness/noise. Based on existing models, 90 HU threshold offers a confidence interval of approximately 95% and 130 HU more than 99%.Historical thresholds offer high confidence intervals for exclusion of aortic blood/myocardium and by the way for detecting calcifications. Nevertheless, considering the large variations of blood/myocardium CT values and the influence of patient's characteristics, a better approach might be an adaptive threshold.

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adaptive threshold patients standard deviations sd intraindividual variation mdct sternum and noise sd of air attenuations interindividual variation attenuationsd attenuations of aortic bloodmyocardium intrainterindividual variations attenuation fat pad thickness calcium scoring nonenhanced calcifications bloodmyocardium ct values

Salah D Qanadli,Anne-Marie Jouannic,Jamshid Dehmeshki,Tri-Linh Lu,.CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT.. 10 (4),.

Salah D Qanadli,Anne-Marie Jouannic,Jamshid Dehmeshki,Tri-Linh Lu,"CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT." 10

Salah D Qanadli,Anne-Marie Jouannic,Jamshid Dehmeshki,Tri-Linh Lu,"CT attenuation values of blood and myocardium: rationale for accurate coronary artery calcifications detection with multi-detector CT."