Welland Spencer H, Kim Grace Hyun J, Yadav Anil, Hoffman John M, Hsu William, Brown Matthew S, Tavakkol Elham, Nael Kambiz, McNitt-Gray Michael F
Center for Computer Vision and Imaging Biomarkers, Department of Radiological Sciences, David Geffen School of Medicine at UCLA, 924 Westwood Blvd. Ste 650, Los Angeles, USA.
Medical & Imaging Informatics, Department of Radiological Sciences, David Geffen School of Medicine at UCLA, 924 Westwood Blvd. Ste 420, Los Angeles, USA.
Proc SPIE Int Soc Opt Eng. 2024 Feb;12927. doi: 10.1117/12.3006582. Epub 2024 Apr 3.
To rule out hemorrhage, non-contrast CT (NCCT) scans are used for early evaluation of patients with suspected stroke. Recently, artificial intelligence tools have been developed to assist with determining eligibility for reperfusion therapies by automating measurement of the Alberta Stroke Program Early CT Score (ASPECTS), a 10-point scale with > 7 or ≤ 7 being a threshold for change in functional outcome prediction and higher chance of symptomatic hemorrhage, and hypodense volume. The purpose of this work was to investigate the effects of CT reconstruction kernel and slice thickness on ASPECTS and hypodense volume.
The NCCT series image data of 87 patients imaged with a CT stroke protocol at our institution were reconstructed with 3 kernels (H10s-smooth, H40s-medium, H70h-sharp) and 2 slice thicknesses (1.5mm and 5mm) to create a reference condition (H40s/5mm) and 5 non-reference conditions. Each reconstruction for each patient was analyzed with the Brainomix e-Stroke software (Brainomix, Oxford, England) which yields an ASPECTS value and measure of total hypodense volume (mL).
An ASPECTS value was returned for 74 of 87 cases in the reference condition (13 failures). ASPECTS in non-reference conditions changed from that measured in the reference condition for 59 cases, 7 of which changed above or below the clinical threshold of 7 for 3 non-reference conditions. ANOVA tests were performed to compare the differences in protocols, Dunnett's post-hoc tests were performed after ANOVA, and a significance level of < 0.05 was defined. There was no significant effect of kernel ( = 0.91), a significant effect of slice thickness ( < 0.01) and no significant interaction between these factors ( = 0.91). Post-hoc tests indicated no significant difference between ASPECTS estimated in the reference and any non-reference conditions. There was a significant effect of kernel ( < 0.01) and slice thickness ( < 0.01) on hypodense volume, however there was no significant interaction between these factors ( = 0.79). Post-hoc tests indicated significantly different hypodense volume measurements for H10s/1.5mm ( = 0.03), H40s/1.5mm ( < 0.01), H70h/5mm ( < 0.01). No significant difference was found in hypodense volume measured in the H10s/5mm condition ( = 0.96).
Automated ASPECTS and hypodense volume measurements can be significantly impacted by reconstruction kernel and slice thickness.
为排除出血情况，非增强CT（NCCT）扫描用于疑似中风患者的早期评估。最近，已开发出人工智能工具，通过自动测量阿尔伯塔中风项目早期CT评分（ASPECTS）来协助确定再灌注治疗的适用性。ASPECTS是一个10分制量表，评分>7或≤7是功能预后预测变化及出现症状性出血几率更高的阈值，同时还用于测量低密度体积。本研究的目的是调查CT重建核和层厚对ASPECTS及低密度体积的影响。
对我院采用CT中风协议成像的87例患者的NCCT系列图像数据，用3种核（H10s - 平滑、H40s - 中等、H70h - 锐利）和2种层厚（1.5mm和5mm）进行重建，以创建一个参考条件（H40s/5mm）和5种非参考条件。使用Brainomix e - 中风软件（Brainomix，英国牛津）对每位患者的每次重建进行分析，该软件可得出ASPECTS值及总低密度体积（mL）的测量值。
在参考条件下，87例中有74例返回了ASPECTS值（13例失败）。59例非参考条件下的ASPECTS值与参考条件下测量的值有所不同，其中7例在3种非参考条件下的变化高于或低于临床阈值7。进行方差分析以比较不同方案之间的差异，方差分析后进行Dunnett事后检验，并定义显著性水平<0.05。核（P = 0.91）无显著影响，层厚（P < 0.01）有显著影响，且这些因素之间无显著交互作用（P = 0.91）。事后检验表明，参考条件下估计的ASPECTS值与任何非参考条件下的ASPECTS值之间无显著差异。核（P < 0.01）和层厚（P < 0.01）对低密度体积有显著影响，然而这些因素之间无显著交互作用（P = 0.79）。事后检验表明，H10s/1.5mm（P = 0.03）、H40s/1.5mm（P < 0.01）、H70h/5mm（P < 0.01）的低密度体积测量值有显著差异。在H10s/5mm条件下测量的低密度体积未发现显著差异（P = 0.96）。
重建核和层厚可对自动ASPECTS及低密度体积测量产生显著影响。
