Abstract
BACKGROUND: Due to the low contrast between the vascular lumen and vessel wall, conventional computed tomography (CT) is not an effective method for visualizing the vessel wall. The purpose of this study was to assess the feasibility of vessel wall visualization using contrast-enhanced dual-energy CT (DECT)-derived water-calcium material decomposition (WMD) and subtraction-based dark-blood imaging (DBI). An additional objective of this study was to determine the association of descending aorta wall thickness (WT) and wall area (WA) with cardiovascular disease (CVD) risk factors and to ascertain the potential of DECT-derived WT and WA as image markers for identifying individuals at high risk for future CVD. METHODS: In this cross-sectional study, virtual noncontrast (VNC), subtraction-based DBI, and WMD images of 106 patients were generated from the arterial-phase DECT data files. To assess the vessel wall visualization, the contrast-to-noise ratios (CNRs) of the descending aorta between the vessel wall and lumen or periaortic fat ( CNRswall-lumen or CNRswall-fat ) were calculated and compared in VNC, subtraction-based DBI, and WMD images. Subsequently, two radiologists independently assessed the vessel wall visualization of these three kinds of images using a four-point scale. To evaluate the association between WT or WA and CVD risk factors, descending aortic WT and WA were measured in the subtraction-based DBI and WMD images, while interobserver agreement was assessed through intraclass correlation coefficients (ICCs). The relationship between the WT or WA and CVD risk factors was determined using univariate and multiple regression analyses. RESULTS: Both WMD and subtraction-based DBI images demonstrated superior CNRswall-lumen and qualitative scores as compared to VNC images ( CNRswall-lumen : 0.59±0.47, 4.36±2.14, and 4.81±3.28, respectively; qualitative scores: 1.04±0.71, 2.53±0.50, and 2.92±0.27, respectively; for virtual non-contrast, subtraction-based DBI and WMD images respectively, all P values <0.05), which indicated better image qualities for vessel wall imaging. The mean descending aorta WT values were 2.18±0.27 and 2.17±0.27 mm for observer 1 and 2.14±0.27 and 2.15±0.26 mm for observer 2 in the subtraction-based DBI and WMD images, respectively. Age and smoking status were predictors for both WT and WA, while males had higher WA values than did females. Blood pressure was only significant for WA measured in subtraction-based DBI. CONCLUSIONS: Both subtraction-based DBI and WMD images in DECT can be used to effectively visualize vessel walls and measure WT and WA, with both measurements demonstrating a positive correlation with CVD risk factors of age and smoking.