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Recent advances in dual-energy imaging techniques, dual-energy subtraction radiography (DESR) and dual-energy CT (DECT), offer new and useful additional information to conventional imaging, thus improving assessment of cardiothoracic abnormalities. DESR facilitates detection and characterization of pulmonary nodules. Other advantages of DESR include better depiction of pleural, lung parenchymal, airway and chest wall abnormalities, detection of foreign bodies and indwelling devices, improved visualization of cardiac and coronary artery calcifications helping in risk stratification of coronary artery disease, and diagnosing conditions like constrictive pericarditis and valvular stenosis. Commercially available DECT approaches are classified into emission based (dual rotation/spin, dual source, rapid kilovoltage switching and split beam) and detector-based (dual layer) systems. DECT provide several specialized image reconstructions. Virtual non-contrast images (VNC) allow for radiation dose reduction by obviating need for true non contrast images, low energy virtual mono-energetic images (VMI) boost contrast enhancement and help in salvaging otherwise non-diagnostic vascular studies, high energy VMI reduce beam hardening artifacts from metallic hardware or dense contrast material, and iodine density images allow quantitative and qualitative assessment of enhancement/iodine distribution. The large amount of data generated by DECT can affect interpreting physician efficiency but also limit clinical adoption of the technology. Optimization of the existing workflow and streamlining the integration between post-processing software and picture archiving and communication system (PACS) is therefore warranted.
RESUMO
Objective To discuss the value of 16-slice spiral CT urography in clinical diagnosis.Methods To compare the images between CR excretory urography,CT and MPR,which are the results of 26 cases who were examined by both CR and 16-slice spiral CT urography.Results From the comparison,it is found that the spiral CT urography images are better than that of the CR excertory urography,and at the same time,the relationship between the parenchyma of the renal,renal pelvis,ureter,bladder and the urinary organs and adjacent structures can be demonstrated clearly.Conclusion The scanning time of the spiral CT is shorter.The machine can not only reconstruct powerfully but also work out better images,and the result is better than CR excretory urography which can not detect some details in its images.Therefore CR excretory urogaphy can be replaced by 16-slice spiral CT urography regardless of its cost.