Quantification of Fat Fraction in the Liver Using Dual Energy Computed Tomography and Multi-material Decomposition

학위논문 (석사)-- 서울대학교 대학원 : 의학과, 2014. 2. 이정민.Purpose: To evaluate the feasibility and accuracy of dual-energy CT (DECT) using multi-material decomposition (MMD) for quantification of the hepatic fat fraction (HFF) and to evaluate the diagnostic performance compared with the precontrast CT number using the histologic examination as the reference standard and MR fat quantification as the technical standard. Methods: This study was approved by our Institutional Animal Care and Use Committee and our Institutional Review Board. In this animal study, various degrees of fatty liver were induced in 16 rabbits in four groups, by feeding them a high-fat, high-cholesterol diet during 0, two, four, and six weeks, respectively. After 6 weeks, precontrast, single-energy CT and multiphasic DECT were performed and HFF maps were obtained from the multiphasic DECT using MMD. Chemical shift MRI for obtaining the fat fraction map and histologic examinations of the liver were also performed. In a human study, 14 living liver donors and 11 liver recipients were included and all study subjects underwent CT using dual-energy precontrast imaging, chemical shift MRI for the fat fraction map, and surgery. The CT attenuation values and fat fractions of the DECT, MRI, and pathology results were measured. The Pearsons correlations coefficients were calculated, and Bland-Altman analysis was performed among the fat fractions of DECT, MRI, and pathology. Receiver operating characteristic (ROC) curve analysis was performed to detect ≥ 5% or ≥ 10% hepatic steatosis. Results: The CT attenuation of precontrast images showed a strongly negative linear correlation with the histologic HFF. In the animal study, the HFFs of DECT with MMD were strongly correlated with those of pathology and MRI, and the mean differences of the Bland-Altman plots comparing the fat fractions of multiphasic DECT with MMD were very close to zero, even in the presence of iodinated contrast media. However, there was poor agreement between the HFF of DECT with MMD and that of pathology. In the human study, the HFF of DECT with MMD showed good agreement with those of MRI and the pathology results, even though there was no significant linear correlation between the HFF of DECT with MMD and that of pathology. The diagnostic performance of DECT with MMD regarding sensitivity and specificity was comparable to that of precontrast CT and MRI (P = 0.17-0.82). Conclusions: The quantification of HFF using DECT with MMD is well-correlated and shows good agreement with the HFF of pathology and MRI even in the presence of iodinated contrast media, and has comparable sensitivity and specificity to those of precontrast CT and MRI.Abstract in English i Contents iii List of Tables iv List of Figures v List of Abbreviations vi Introduction 1 1. Animal Study Material and Methods 5 Results 13 2. Human Study Material and Methods 35 Results 40 Discussion 47 References 52 Abstract in Korean 62Maste