双层探测器光谱CT定量评估心力衰竭患者细胞外容积的可行性研究

Quantitative evaluation of extracellular volume in patients with heart failure using dual-layer spectral detector CT:a feasibility study

目的以MRI为参照,探讨不同延迟强化容积占比下双层探测器光谱CT定量评估心力衰竭患者心肌节段细胞外容积(ECV)的可行性。方法前瞻性纳入2019年7月至2021年1月在北京协和医院诊断为心力衰竭的患者27例,所有入组患者均在1周内行心脏光谱CT和MR检查,根据MR图像上每个心肌节段延迟强化容积占比,将心脏节段分为3组:A组(0~4%)、B组(5%~49%)和C组(50%~100%)。由2名医师分别测量并计算相应的心肌ECV。整体心肌及每组心肌节段的CT-ECV和MRI-ECV的相关性分析采用Spearman检验,一致性采用Bland-Altman检验。2名医师测量的CT-ECV和MRI-ECV组内一致性采用ICC评价。结果27例患者共432个心脏节段,其中A组199个心脏节段,B组151个心脏节段,C组82个心脏节段。27例患者整体心肌CT-ECV为32.25%(28.04%,34.28%),MRI-ECV为32.27%(28.35%,34.77%),两者间相关性很高(r=0.969,P<0.001)。CT-ECV和MRI-ECV一致性分析的偏倚为0.4%(95%CI-6.9%~7.8%)。A、B、C 3组CT-ECV分别为28.23%(26.18%,29.92%)、33.29%(30.16%,35.96%)和40.22%(34.06%,46.70%),3组间差异有统计学意义(H=209.219,P<0.001)。A、B、C 3组内CT-ECV和MRI-ECV的相关性依次升高,相关系数分别为0.614(P<0.001)、0.852(P<0.001)和0.953(P<0.001)。A、B、C 3组内CT-ECV和MRI-ECV的一致性偏倚较小,分别为2.0%(95%CI-17.6%~21.6%)、-0.4%(95%CI-13.8%~12.9%)和-1.8%(95%CI-17.4%~13.9%)。2名放射科医师测量CT-ECV和MRI-ECV组内一致性ICC分别为0.877和0.945。结论心肌延迟强化容积占比越高,CT-ECV和MRI-ECV的相关性越大,CT-ECV可作为MRI-ECV替代的影像学检查方法,用于定量评价心力衰竭患者的心肌组织特征。

Objective To explore the feasibility in evaluating segmental extracellular volume(ECV)using dual-layer spectral detector CT in patients with heart failure with various percentages of delayed hyper-enhanced volume,using MRI as a reference.Methods Twenty-seven patients with heart failure in Peking Union Medical College Hospital were prospectively enrolled in this study from July 2019 to January 2021.All the patients underwent both CT late iodine enhancement and MR late gadolinium enhancement imaging within a week.According to percentages of hyper-enhanced volume on cardiac MR image,myocardial segments were classified into 3 groups:0-4%(group A),5%-49%(group B)and 50%-100%(group C).ECV images were independently observed by 2 experienced radiologists.The correlation and agreement between CT-ECV and MRI-ECV for the whole myocardial assessment and for the segmental assessment were evaluated using Spearman correlation and Bland-Altman analysis.Inter-observer agreement was assessed using the ICC.Results Of the 27 patients,432 segments were analyzed,with 199 segments in group A,151 segments in group B and 82 segments in group C.In the whole myocardial analysis,the CT-ECV and MRI-ECV were 32.25%(28.04%,34.28%)and 32.27%(28.35%,34.77%),respectively.A good correlation was found between CT-ECV and MRI-ECV(r=0.969,P<0.001).Bland-Altman analysis between CT-ECV and MRI-ECV showed a small bias(0.4%),with 95%limits of agreement of-6.9%to 7.8%.as for the segmental myocardial assessment,the CT-ECV was 28.23%(26.18%,29.92%)for group A,33.29%(30.16%,35.96%)for group B and 40.22%(34.06%,46.70%)for group C.There was statistically significant difference in ECV among three groups(all P<0.001).Good correlations between CT-ECV and MRI-ECV were found in group A(r=0.614,P<0.001),group B(r=0.852,P<0.001)and group C(r=0.953,P<0.001).Bland-Altman analysis between CT-ECV and MRI-ECV showed a small bias 2.0%(95%limits of agreement:-17.6%-21.6%)in group A,a small bias-0.4%(95%limits of agreement:-13.8%-12.9%)in group B and a small bias-1.8%(95%limits of agreement:-17.4%-13.9%)in group C.The ICC values between 2 observers were 0.877 and 0.945 on CT-ECV and MRI-ECV,respectively.Conclusions The larger percentage of hyper-enhanced volume on cardiac MR image,the stronger correlation are between the CT-ECV and MRI-ECV.CT-ECV may be taken as an alternative tool for quantitative evaluation of myocardial tissue in patients with heart failure.