Gohmann Robin F, Gottschling Sebastian, Seitz Patrick, Temiz Batuhan, Krieghoff Christian, Lücke Christian, Horn Matthias, Gutberlet Matthias
Department of Diagnostic and Interventional Radiology, Heart Center Leipzig, Leipzig, Germany.
Medical Faculty, University of Leipzig, Leipzig, Germany.
Quant Imaging Med Surg. 2021 Feb;11(2):697-705. doi: 10.21037/qims-20-907.
Adipose tissue as part of body composition analysis may serve as a powerful biomarker. Validation of segmented adipose tissue and correlation to clinical data has been performed on non-enhanced scans (NES). As many patients require a contrast enhanced scan (CES) for other aspects of clinical decision making, the utility of CES for body composition analysis would be most useful. Therefore, we analyzed the influence of iodinated contrast medium (ICM) and contrast phase on the characterization and segmentation of adipose tissue.
Exams of 31 patients undergoing multi-phasic CT at identical scan settings containing an NES were retrospectively included. In addition to NES, patients received an arterial (ART) (n=23), portal-venous (PVN) (n=10), and/or venous scan (VEN) (n=31) after intravenous injection of 90 mL ICM. Density and volume of adipose tissue were quantified semi-automatically with thresholds between -190 HU and -30 HU and recorded separately for visceral (VAT) and subcutaneous adipose tissue (SAT). Density and volume of total adipose tissue (TAT) were computed. For conversion of values from CES into those of NES regression analyses were performed and tested.
Density of adipose tissue increased after application of ICM more on later scans (VEN ≈ PVN > ART) and more markedly in VAT than SAT (VAT > TAT > SAT). Except in SAT on ART, all changes were significant (P<0.001). Measured volume of adipose tissue decreased on all CES (VEN ≈ PVN > ART) (P<0.001), but only reached statistical significance for VAT and TAT (VAT > TAT) on all CES (P<0.05). Density and volume in CES correlate extremely well with NES and may be calculated from one another [root-mean-square error (RMSE): <6 HU; <0.85 dm].
Density and volume of segmented adipose tissue are altered by the injection of ICM in differing degrees between compartments and contrast phases. However, as the effect of ICM is fairly constant for a given compartment and contrast phase, values may be converted into those of NES with relative precession. This conversion allows body composition analysis to be carried out also in contrast enhanced CT examinations, e.g., for risk stratification and the comparison of the obtained results to previous studies.
脂肪组织作为身体成分分析的一部分，可能是一种强大的生物标志物。已在非增强扫描（NES）上对分割的脂肪组织进行了验证，并与临床数据进行了相关性分析。由于许多患者因临床决策的其他方面需要进行增强扫描（CES），因此CES在身体成分分析中的应用将非常有用。因此，我们分析了碘化造影剂（ICM）和造影剂阶段对脂肪组织特征和分割的影响。
回顾性纳入31例在相同扫描设置下接受多期CT检查且包含NES的患者。除NES外，患者在静脉注射90 mL ICM后接受动脉期（ART）（n = 23）、门静脉期（PVN）（n = 10）和/或静脉期扫描（VEN）（n = 31）。脂肪组织的密度和体积通过在-190 HU至-30 HU之间的阈值进行半自动量化，并分别记录内脏脂肪组织（VAT）和皮下脂肪组织（SAT）的情况。计算总脂肪组织（TAT）的密度和体积。对CES值与NES值进行回归分析并测试，以将CES值转换为NES值。
应用ICM后，脂肪组织的密度在后期扫描中增加得更多（VEN≈PVN>ART），且在内脏脂肪组织中比皮下脂肪组织增加得更明显（VAT>TAT>SAT）。除了动脉期的皮下脂肪组织外，所有变化均具有统计学意义（P<0.001）。所有增强扫描期（VEN≈PVN>ART）脂肪组织的测量体积均减少（P<0.001），但仅在内脏脂肪组织和总脂肪组织中达到统计学意义（VAT>TAT）（P<0.05）。增强扫描中的密度和体积与非增强扫描相关性非常好，并且可以相互计算得出[均方根误差（RMSE）：<6 HU；<0.85 dm³]。
分割的脂肪组织的密度和体积在不同腔室和造影剂阶段因注射ICM而有不同程度的改变。然而，由于对于给定的腔室和造影剂阶段，ICM的影响相当恒定，因此可以相对精确地将值转换为非增强扫描的值。这种转换使得在增强CT检查中也可以进行身体成分分析，例如用于风险分层以及将获得的结果与先前的研究进行比较。
