Hoffmann U, Butler J
Department of Radiology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA.
Int J Obes (Lond). 2005 Sep;29 Suppl 2:S46-53. doi: 10.1038/sj.ijo.0803083.
Coronary artery disease continues to be one of the leading causes of death and disability around the globe, challenging the efficacy of currently applied schemes to predict the risk for future coronary events. In fact, algorithms such as the Framingham risk score that are based on traditional risk factors like hypertension and dyslipidemia are not very sensitive, leaving a majority of the population at intermediate risk.
Advances in multidetector computed tomography (MDCT) technology with submillimeter slice collimation (approximately 0.6 mm) and high temporal resolution now permit contrast-enhanced imaging of the coronary artery lumen and wall in a single breath hold. The current generation of MDCT provided in-plane resolution of 0.5 mm and a temporal resolution of 210 ms. The simultaneous acquisition of 16/64 parallel cross-sections reduces image acquisition time to about 10-20s using 60-80 ml of contrast agents to opacify the coronary artery lumen. CT imaging for coronary calcification is an established method with low radiation exposure. The amount of calcification is expressed as an Agatston Score (AS).
The presence and amount of coronary calcification significantly increases the relative risk for future coronary events, independent from traditional risk factors (risk ratio 8.7 [95% Cl, 2.7-28.1]). Especially, individuals with a high AS (>400) who are at intermediate 10-y Framingham event risk may benefit from this additional risk stratification. However, calcification is rarely present in children and adolescents. However, there is a growing body of evidence suggesting that contrast-enhanced MDCT can detect both calcified and noncalcified plaques with high sensitivity and specificity for the detection of plaques > 0.5 mm when compared to intravascular ultrasound. Moreover, initial data suggest that plaque characteristics such as plaque area, volume, quantify and coronary plaque remodeling index can be quantified in good agreement with IVUS. The composition of noncalcified plaque may be further stratified into predominantly fibrous or lipid-rich plaque. Noncalcified plaque may be present already in children and adolescents with multiple risk factors.
The available data indicate that high resolution MDCT can reliably detect, quantify and characterize calcified and noncalcified coronary atherosclerotic plaque. With MDCT, we now have a unique opportunity to study the natural history and response to therapy of noncalcified coronary plaques, which may be already present in obese children or children with multiple risk factors.
冠状动脉疾病仍然是全球死亡和残疾的主要原因之一，这对当前用于预测未来冠状动脉事件风险的方案的有效性提出了挑战。事实上，诸如基于高血压和血脂异常等传统风险因素的弗明汉姆风险评分等算法并不十分敏感，使得大多数人群处于中等风险水平。
具有亚毫米层厚准直（约0.6毫米）和高时间分辨率的多排螺旋计算机断层扫描（MDCT）技术的进步，现在允许在一次屏气中对冠状动脉腔和壁进行对比增强成像。当前一代的MDCT提供了0.5毫米的平面分辨率和210毫秒的时间分辨率。同时采集16/64个平行横截面，使用60 - 80毫升造影剂使冠状动脉腔显影，将图像采集时间减少到约10 - 20秒。用于冠状动脉钙化的CT成像是一种辐射暴露低的成熟方法。钙化量用阿加斯顿评分（AS）表示。
冠状动脉钙化的存在和程度显著增加了未来冠状动脉事件的相对风险，独立于传统风险因素（风险比8.7 [95%可信区间，2.7 - 28.1]）。特别是，10年弗明汉姆事件风险处于中等水平且阿加斯顿评分高（>400）的个体可能会从这种额外的风险分层中受益。然而，钙化在儿童和青少年中很少见。然而，越来越多的证据表明，与血管内超声相比，对比增强MDCT能够以高灵敏度和特异性检测钙化和非钙化斑块，对于检测大于0.5毫米的斑块。此外，初步数据表明，斑块特征如斑块面积、体积、量化和冠状动脉斑块重塑指数可以与血管内超声很好地一致量化。非钙化斑块的成分可以进一步分层为主纤维性或富含脂质的斑块。有多种风险因素的儿童和青少年中可能已经存在非钙化斑块。
现有数据表明，高分辨率MDCT能够可靠地检测、量化和表征钙化和非钙化冠状动脉粥样硬化斑块。借助MDCT，我们现在有一个独特的机会来研究非钙化冠状动脉斑块的自然史和对治疗的反应，这些斑块可能已经存在于肥胖儿童或有多种风险因素的儿童中。
