The Experimental And Clinical Studies On Dual Dual-energy Imaging For The Diagnosis Of Acute Pulmonary Embolism Using Dual-source CT

Despite its high prevalence, acute pulmonary embolism (PE) is difficult to diagnose and ease to misdiagnosis and missed diagnosis because of having no specific signs or symptoms of PE. Although its value of diagnosis in PE is increased with the development of hardware and software of spiral CT, it allows direct visualization of emboli only and does not provide information on pulmonary perfusion. Dynamic scanning can evaluate the lung perfusion, but it cannot cover the entire lung because of small detector aperture. Measuring densitometry of the lung and subtraction technique can access the pulmonary perfusion but post processing of CT data is complex and timing. Recently, with the developed of Dual-energy contrast-enhanced computed tomography technology, it is hope that perfusion imaging of lung using CT to become the routine Screening method for PE. To create animal model of rabbits acute pulmonary embolism, the aim of this study is to evaluate value of dual-energy perfusion imaging in diagnosis of acute pulmonary embolism based on the standard of pathology Part One The experimental studies on dual-energy imaging for the diagnosis of acute pulmonary embolism using dual-source CTObject To create animal model of rabbits acute pulmonary embolism, analysis the relation between the color of dual-energy perfusion imaging and blood distribution of lung by measuring the densitometry of lung parenchyma, and evaluate the feasibility and value of dual-energy perfusion imaging in diagnosis of acute pulmonary embolism based on the standard of pathology.Materials and methods 1. Eight New Zealand rabbits were first underwent dual-source CT to confirm them healthy. The scan protocol consisting of a standard unenhanced scan and a contrast enhancement with iodixanol (300mgI/ml) were performed. The contrast enhancement scan were acquired in the dual-energy model.2.After undergoing the dual-source CT, the experimental pulmonary model was made under fluoroscopy guidance. A vascular sheath was pricked into the exposing the external jugular vein of the rabbit and the tip of sheath was located at left lower pulmonary artery embolized with strip gelatin sponges powder. When filling defect or complete obstruction of pulmonary arteries was found under DSA, the model of PE was demonstrated successfully.3.The rabbits of pulmonary embolism model were underwent dual-source CT again. 4. After completing the dual source CT imaging, the rabbits were killed by intravenously injecting an excessive dose of thiopental sodium. The lung were removed and fixed .The fixed lungs were sliced in a transverse plane. The lung were craniocaudally divided into5 parts: right upper lobe, right middle lobe, right lower lobe, left upper lobe, right lower lobe. The location and number of the embolism in these slices were recorded. 5. On the workstation, the image processing and imaging evaluation were made. Based on the pathology, to measurement the density of region of interest (ROI). After imaging processing with LungPBV software, CTA, dual-energy perfusion imaging and fusion imaging were obtained. On CTA, the observers were recommended to record the location and number of the embolism. On the dual-energy perfusion images and fusion images, the observers were recommended to record the location and number of perfusion abnormality. 6. With the pathology results as the reference standards, the sensitivities, specificity values were calculated for all methods. Statistical analyses were performed using SPSS software, The McNamara Test was used to determine the statistical significance of the differences between each method and pathology. The paired samples T test was used to determine the statistical significance of the differences between the values of CT.Results Before and after embolism, measurements from CT of those segments with embolismic region showed no statistically different on the unenhanced image but showed significant statistically different on the enhanced image. When compared to segments with normal pulmonary region after embolism, those segments with embolismic region showed no statistically different on the unenhanced image but showed significant statistically different on the enhanced image. On dual-energy perfusion imaging of embolism, those segments with embolismic region showed statistically different comparing to segments with normal pulmonary region. The sensitivities and specificity values of CTA is 66.67 % and 100% ,respectively. There is no statistically different comparing to pathology. The sensitivity,specificity values of dual-energy perfusion image is 88.89% and, 91.67%, respectively. There is no statistically different comparing to pathology. Conclusion 1.Comparing to unenhanced image, dual—source CT contrast scan is helpful to detect the embolismic region.2. Our initial experience indicates that dual-energy perfusion imaging is able to display the blood distribution of rabbit's lung.3. . The sensitivities and specificity values of dual-energy perfusion image in diagnosis of acute pulmonary embolism are high. The fusion image of CTA and dual-energy perfusion imaging can improve the value of embolism in small artery.Part Two The clinical studies on dual-energy imaging for the diagnosis of acute pulmonary embolism using dual-source CTObject To initially study the diagnosis value of acute pulmonary embolism on dual-energy imaging using dual-source CT.Materials and methods Twelve consecutive patients underwent dual-energy imaging using dual-source CT for suspected pulmonary embolism. On the workstation, the image processing and imaging evaluation were made by lung PBV software. CTPA, DEPI and fusion image were obtained. CTPA and fusion images were reviewed independently by 2 board-certified radiologists. CTPA images were reviewed first, and 1 week later, DEPI were reviewed. The presence or absence of the embolism was scored using 5-point scale. The scores for pulmonary embolism on CTPA and DEPI were compared using a weighted Kappa analysis.Results The agreement of the scores between CTPA and DEPI was moderate agreement with the Kappa value of 0.785 and 0.688 independently. The agreement of the scores between different reviewers was perfect agreement onDEPI with the Kappa value of 0.792.Conclusion Compared with CTPA, DEPI had moderate agreement and goodreproducibility. The curative effect of PE was assessed by DEPI. Therefore, thereis good perspective for DEPI in clinical.