Nickoloff E L, Perman W H, Esser P D, Bashist B, Alderson P O
Radiology. 1984 Aug;152(2):511-5. doi: 10.1148/radiology.152.2.6739824.
Absolute left ventricular volume has been calculated from gated blood pool studies by estimating an attenuation correction for left ventricular counts. We studied the physical basis of these corrections by evaluating x-ray photon attenuation from CT scans of the thorax (10 second scans, no gating). CT numbers were converted to linear attenuation coefficients (LACs) at 140 keV, and LACs from the center of the left ventricle or esophagus to the chest wall (40 degrees left anterior oblique position) were determined in 12 patients of various body habitus. The mean LACs were virtually identical (0.13 cm-1 +/- 0.02 cm-1 SD), but were less than the LAC of water (0.15 cm-1). However, the esophagus was 66% further from the chest wall than the center of the left ventricle. These results suggest that conventional methods overestimate attenuation and show that LAC variability between individuals can be large. Better methods of attenuation correction may improve count-based estimates of left ventricular volume.
通过对左心室计数进行衰减校正，从门控血池研究中计算出绝对左心室容积。我们通过评估胸部CT扫描（10秒扫描，无门控）的X射线光子衰减来研究这些校正的物理基础。将CT数值转换为140keV时的线性衰减系数（LAC），并在12名不同体型的患者中确定从左心室中心或食管到胸壁（左前斜40度位置）的LAC。平均LAC实际上是相同的（0.13 cm-1±0.02 cm-1标准差），但低于水的LAC（0.15 cm-1）。然而，食管到胸壁的距离比左心室中心到胸壁的距离远66%。这些结果表明，传统方法高估了衰减，并表明个体之间的LAC变异性可能很大。更好的衰减校正方法可能会改善基于计数的左心室容积估计。
