Gomolka R S, Chrzan R M, Urbanik A, Kazmierski R, Grzanka A D, Nowinski W L
1 The Faculty of Electronics and Information Technology, Warsaw University of Technology, Warsaw, Poland.
2 Department of Radiology, Jagiellonian University, The Cracow University Hospital, Krakow, Poland.
Neuroradiol J. 2017 Feb;30(1):15-22. doi: 10.1177/1971400916678226. Epub 2017 Jan 6.
Introduction Accurate identification of infarcts in non-contrast computed tomography (NC-CT) scans of the brain is fundamental in the diagnosis and management of patients with stroke. Quantification of image contrast properties at the boundaries of ischemic infarct regions in NC-CT can contribute to a more precise manual or automatic delineation of these regions. Here we explore these properties quantitatively. Methods We retrospectively investigated 519 NC-CT studies of 425 patients with clinically confirmed ischemic strokes. The average and standard deviation (SD) of patients' age was 67.5 ± 12.4 years and the average(median)±SD time from symptoms onset to NC-CT examination was 27.4(12)±35.7 h. For every scan with an ischemic lesion identified by experts, the image contrast of the lesion vs. normal surrounding parenchyma was calculated as a difference of mean Hounsfield Unit (HU) of 1-5 consecutive voxels (the contrast window width) belonging to the lesion and to the parenchyma. This contrast was calculated at each single voxel of ischemic lesion boundaries (previously delineated by the experts) in horizontal and vertical directions in each image. The distributions of obtained horizontal, vertical and both contrasts combined were calculated among all 519 NC-CTs. Results The highest applicative contrast window width was identified as 5 voxels. The ischemic infarcts were found to be characterized by 6.60 HU, 8.28 HU and 7.55 HU mean values for distributions of horizontal, vertical and combined contrasts. Approximately 40-50% of the infarct boundary voxels were found to refer to the image contrast below 5 HU. Conclusion Low image contrast of ischemic lesions prevents accurate delineation of the infarcts in NC-CT.
引言 在脑部非增强计算机断层扫描（NC-CT）中准确识别梗死灶是中风患者诊断和治疗的基础。定量分析NC-CT中缺血性梗死区域边界的图像对比度特性有助于更精确地手动或自动勾勒这些区域。在此，我们对这些特性进行定量研究。
方法 我们回顾性研究了425例临床确诊为缺血性中风患者的519份NC-CT研究。患者的平均年龄和标准差（SD）为67.5±12.4岁，从症状发作到NC-CT检查的平均（中位数）±SD时间为27.4（12）±35.7小时。对于专家确定有缺血性病变的每次扫描，将病变与周围正常实质的图像对比度计算为属于病变和实质的1-5个连续体素（对比度窗口宽度）的平均亨氏单位（HU）之差。在每个图像的水平和垂直方向上，在缺血性病变边界的每个单一体素（先前由专家勾勒）处计算这种对比度。计算所有519份NC-CT中获得的水平、垂直和两者组合对比度的分布。
结果 确定最高适用对比度窗口宽度为5个体素。发现缺血性梗死灶的水平、垂直和组合对比度分布的平均值分别为6.60 HU、8.28 HU和7.55 HU。发现约40-50%的梗死灶边界体素的图像对比度低于5 HU。
结论 缺血性病变的低图像对比度妨碍了在NC-CT中准确勾勒梗死灶。
