Mamopoulos Apostolos T, Freyhardt Patrick, Touloumtzidis Aristotelis, Zapenko Alexander, Katoh Marcus, Gäbel Gabor
Faculty of Medicine, Saarland University, Kirrbergerstrasse 100, D-66421, Homburg/Saar, Germany.
Department of Vascular Surgery, HELIOS Klinikum Krefeld, Lutherplatz 40, 47805, Krefeld, Germany.
Int J Cardiovasc Imaging. 2022 Jul;38(7):1621-1633. doi: 10.1007/s10554-022-02561-8. Epub 2022 Feb 26.
To examine the feasibility of the quantification of abdominal periaortic fat tissue (PaFT) (tissue within - 45 to - 195 HU) in enhanced CT-angiographies compared to unenhanced CT-scans and identify methodological issues affecting its clinical implementation. Using OsirixMD, PaFT volume and mean HU value were retrospectively measured within a 5 mm periaortic ring in paired unenhanced and enhanced abdominal aortic CT-scans. The correlation between PaFT values was examined in a derivation cohort (n = 101) and linear regression analysis produced correction factors to convert values from enhanced into values from unenhanced CTs. The conversion factors were then applied to enhanced CTs in a different validation cohort (n = 47) and agreement of corrected enhanced values with values from unenhanced scans was evaluated. Correlation between PaFT Volume und Mean HU from enhanced and unenhanced scans was very high (r > 0.99 and r = 0.95, respectively, p < 0.0001 for both). The correction factors for PaFT Volume and Mean HU were 1.1057 and 1.0011. Potential confounding factors (CT-kilovoltage, slice thickness, mean intraluminal contrast density, aortic wall calcification, longitudinal variation of intraluminal contrast density, aortic diameter) showed no significant effect in a multivariate regression analysis (p > 0.05). Bland-Altman analysis of corrected enhanced and unenhanced values showed excellent agreement and Passing-Bablok regression confirmed minimal/no residual bias. PaFT can be quantified in enhanced CT-angiographies very reliably. PaFT Volume scores are very consistently slightly underestimated in enhanced scans by about 10%, while the PaFT Mean HU value remains practically constant and offers distinct methodological advantages. However, a number of methodological issues remain to be addressed.
为了研究在增强CT血管造影中与非增强CT扫描相比，定量腹主动脉周围脂肪组织（PaFT）（-45至-195 HU范围内的组织）的可行性，并确定影响其临床应用的方法学问题。使用OsirixMD，在配对的非增强和增强腹主动脉CT扫描中，在一个5毫米的主动脉周围环内回顾性测量PaFT体积和平均HU值。在一个推导队列（n = 101）中检查PaFT值之间的相关性，并进行线性回归分析以产生校正因子，将增强CT的值转换为非增强CT的值。然后将转换因子应用于另一个验证队列（n = 47）中的增强CT，并评估校正后的增强值与非增强扫描值的一致性。增强扫描和非增强扫描的PaFT体积与平均HU之间的相关性非常高（分别为r > 0.99和r = 0.95，两者p < 0.0001）。PaFT体积和平均HU的校正因子分别为1.1057和1.0011。潜在的混杂因素（CT千伏、层厚、平均腔内对比剂密度、主动脉壁钙化、腔内对比剂密度的纵向变化、主动脉直径）在多变量回归分析中未显示出显著影响（p > 0.05）。对校正后的增强值和非增强值进行Bland-Altman分析显示出极好的一致性，Passing-Bablok回归证实了最小/无残留偏差。PaFT可以在增强CT血管造影中非常可靠地进行定量。在增强扫描中，PaFT体积评分非常一致地被低估约10%，而PaFT平均HU值实际上保持不变，并具有明显的方法学优势。然而，仍有一些方法学问题有待解决。
