Department of Radiology, The University of Chicago, 5841 South Maryland Avenue, Chicago, Illinois 60637, USA.
Med Phys. 2011 Feb;38(2):942-7. doi: 10.1118/1.3537610.
The purpose of this study was to characterize the Hounsfield unit (HU) distributions of mesothelioma and other tissues present in contrast-enhanced thoracic CT scans, to compare the HU distributions of mesothelioma, muscle, and liver by scanner and reconstruction filter/kernel combination, and to assess interpatient HU distribution variability.
The database consisted of 28 contrast-enhanced thoracic CT scans from different patients. For each scan, regions of interest were manually outlined within each of 13 tissues, including mesothelioma. For each tissue, the empirical percentiles in HU values were calculated along with the interpatient variability. The HU distributions of select tissues were compared across three different scanner and reconstruction filter/kernel combinations.
The HU distributions of blood-containing tissues demonstrated substantial overlap, as did the HU distributions of pleural effusion, mesothelioma, muscle, and liver. The HU distribution of fat had the least overlap with the other tissues. Fat and muscle had the lowest interpatient HU variability and the narrowest HU distributions, while blood-containing tissues had the highest interpatient HU variability. A soft-tissue reconstruction filter/kernel yielded the narrowest HU distribution, and fat with artifact had the widest HU distribution.
Characterization of tissues in CT scans enhances the understanding of those tissues' HU distributions. Due to their overlapping HU distributions and close spatial proximity to one another, separating pleural effusion, mesothelioma, muscle, and liver from one another is a difficult task based on HU value thresholding alone. The results illustrate the wide distributions and large variability that exist for tissues present in clinical thoracic CT scans.
本研究旨在描述对比增强胸部 CT 扫描中间皮瘤和其他组织的亨氏单位 (HU) 分布，比较不同扫描仪和重建滤波器/核组合中间皮瘤、肌肉和肝脏的 HU 分布，并评估患者间 HU 分布的可变性。
该数据库包含 28 例来自不同患者的增强胸部 CT 扫描。对于每个扫描，在包括间皮瘤在内的 13 种组织的每个区域内手动勾勒出感兴趣区域。对于每种组织，计算 HU 值的经验百分位数以及患者间的变异性。比较了三种不同的扫描仪和重建滤波器/核组合中选定组织的 HU 分布。
含血液组织的 HU 分布存在很大的重叠，胸腔积液、间皮瘤、肌肉和肝脏的 HU 分布也是如此。脂肪的 HU 分布与其他组织的重叠最小。脂肪和肌肉的患者间 HU 变异性最小，HU 分布最窄，而含血液组织的患者间 HU 变异性最大。软组织重建滤波器/核产生的 HU 分布最窄，带有伪影的脂肪的 HU 分布最宽。
对 CT 扫描中的组织进行特征描述可增强对这些组织 HU 分布的理解。由于它们的 HU 分布重叠且彼此空间接近，仅基于 HU 值阈值来区分胸腔积液、间皮瘤、肌肉和肝脏是一项困难的任务。结果表明，在临床胸部 CT 扫描中存在广泛的分布和较大的变异性。
