Department of Medicine, Division of Cardiology, Johns Hopkins University School of Medicine, 1042 Ross Building, Baltimore, MD 21205, USA.
Radiology. 2010 Jul;256(1):111-8. doi: 10.1148/radiol.10091399.
To fully characterize beam-hardening effects caused by iodinated contrast medium in the left ventricular (LV) cavity and aorta in the assessment of myocardial perfusion at computed tomography (CT) and to validate a beam-hardening artifact correction algorithm that considers fluid-filled vessels and chambers important sources of beam hardening.
The Johns Hopkins University animal care and use committee approved all procedures. An anatomically correct LV and myocardial phantom to characterize beam-hardening artifacts was designed. Following validation in the phantom, the beam-hardening correction (BHC) algorithm was applied to 256-detector row dynamic volume CT images in a canine ischemia model (n = 5) during adenosine stress, and the effect of beam hardening was determined by comparing regional dynamic volume CT perfusion metrics (myocardial upslope normalized by maximum LV blood pool attenuation) with microsphere-derived myocardial blood flow (MBF). A paired Student t test was used to compare continuous variables from the same subject but under different conditions, while linear regression analysis was performed to estimate the slope and statistical significance of the relationship between CT-derived perfusion metrics and microsphere-derived MBF.
Beam-hardening artifacts were successfully reproduced in phantom studies and were eliminated with the BHC algorithm. The correlation coefficient of CT-derived perfusion metrics and microsphere-derived MBF improved from 0.60 to 0.74 (P > .05) following correction in the animal model.
Beam-hardening artifacts confound dynamic volume CT assessment of myocardial perfusion. Application of the BHC algorithm is helpful for improving accuracy of myocardial perfusion at dynamic volume CT.
充分描述碘造影剂引起左心室（LV）腔和主动脉中的束硬化效应，用于评估 CT 心肌灌注，并验证一种考虑充满液体的血管和腔室为重要束硬化源的束硬化伪影校正算法。
约翰霍普金斯大学动物护理和使用委员会批准了所有程序。设计了一个解剖学正确的 LV 和心肌体模，用于描述束硬化伪影。在体模中进行验证后，将束硬化校正（BHC）算法应用于犬缺血模型的 256 探测器动态容积 CT 图像（n = 5），在腺苷应激期间，通过比较区域动态容积 CT 灌注指标（心肌上升斜率与最大 LV 血池衰减归一化）与微球衍生的心肌血流（MBF）来确定束硬化的影响。使用配对学生 t 检验比较同一受试者但在不同条件下的连续变量，同时进行线性回归分析以估计 CT 衍生灌注指标与微球衍生 MBF 之间的关系的斜率和统计学意义。
束硬化伪影在体模研究中得到成功再现，并通过 BHC 算法消除。在动物模型中校正后，CT 衍生灌注指标和微球衍生 MBF 的相关系数从 0.60 提高到 0.74（P >.05）。
束硬化伪影混淆了动态容积 CT 评估心肌灌注。应用 BHC 算法有助于提高动态容积 CT 心肌灌注的准确性。
