Utility of Dual-Energy CT-based Monochromatic Imaging in the Assessment of Myocardial Delayed Enhancement in Patients with Cardiomyopathy

作者：Chang Suyon; Han Kyunghwa; Youn Jong Chan; Im Dong Jin; Kim Jin Young; Suh Young Joo; Hong Yoo Jin; Hur Jin; Kim Young Jin; Choi Byoung Wook; Lee Hye Jeong^*

来源：Radiology, 2018, 287(2): 442-451.

DOI：10.1148/radiol.2017162945

Purpose: To investigate the diagnostic utility of dual-energy computed tomography (CT)-based monochromatic imaging for myocardial delayed enhancement (MDE) assessment in patients with cardiomyopathy.
Materials and Methods: The institutional review board approved this prospective study, and informed consent was obtained from all participants who were enrolled in the study. Forty patients (27 men and 13 women; mean age, 56 years 6 15 [standard deviation]; age range, 22-81 years) with cardiomyopathy underwent cardiac magnetic resonance (MR) imaging and dual-energy CT. Conventional (120-kV) and monochromatic (60-, 70-, and 80-keV) images were reconstructed from the dual-energy CT acquisition. Subjective quality score, contrast-to-noise ratio (CNR), and beam-hardening artifacts were compared pairwise with the Friedman test at post hoc analysis. With cardiac MR imaging as the reference standard, diagnostic performance of dual-energy CT in MDE detection and its predictive ability for pattern classification were compared pairwise by using logistic regression analysis with the generalized estimating equation in a per-segment analysis. The Bland-Altman method was used to find agreement between cardiac MR imaging and CT in MDE quantification.
Results: Among the monochromatic images, 70-keV CT images resulted in higher subjective quality (mean score, 3.38 +/- 0.54 vs 3.15 +/- 0.43; P=.0067), higher CNR (mean, 4.26 +/- 1.38 vs 3.93 +/- 1.33; P=.0047), and a lower value for beam-hardening artifacts (mean, 3.47 +/- 1.56 vs 4.15 +/- 1.67; P<.0001) when compared with conventional CT. When compared with conventional CT, 70-keV CT showed improved diagnostic performance for MDE detection (sensitivity, 94.6% vs 90.4% [P=.0032]; specificity, 96.0% vs 94.0% [P=.0031]; and accuracy, 95.6% vs 92.7% [P<.0001]) and improved predictive ability for pattern classification (subendocardial, 91.5% vs 84.3% [P=.0111]; epicardial, 94.3% vs 73.5% [P=.0001]; transmural, 93.0% vs 77.7% [P=.0018]; mesocardial, 85.4% vs 69.2% [P=.0047]; and patchy. 84.4% vs 78.4% [P=.1514]). For MDE quantification, 70-keV CT showed a small bias 0.1534% (95% limits of agreement: -4.7013, 5.0080).
Conclusion: Dual-energy CT-based 70-keV monochromatic images improve MDE assessment in patients with cardiomyopathy via improved image quality and CNR and reduced beam-hardening artifacts when compared with conventional CT images.