Corroboration of Spiral CT angiography with D-dimer Assays in the accurate diagnosis of Pulmonary Embolism with assessment of its Image quality

Abstract

Introduction: Pulmonary embolism is a frequent cause of mortality and morbidity. Aim of this study was to evaluate the utility of spiral computed tomographic angiography in determining the prevalence of pulmonary embolism in a clinically suspicious group and to assess the image quality of a single source computed tomography in diagnosis of pulmonary embolism. We have also investigated the reliability of D-dimer test in ruling out pulmonary embolism. Materials and Methods: 50 patients clinically suspected of having pulmonary embolism were examined with contrast-enhanced spiral computed tomography in the hospital affiliated to Zhengzhou University from August 2014 to December 2015. Image quality, was assessed by analyzing the attenuation in the pulmonary trunk and its branches in comparison with the background noise. Mean attenuation values and standard deviation were recorded and displayed in Hounsfield Units. The computed tomography values, standard deviation values and signal-noise ratio obtained were then statistically analyzed using SPSS 17.0 software. D-dimer test results were also obtained for the patients suspected of pulmonary embolism using rapid D-dimer testing and a reference range of 0–0.3 µg/l was considered as normal. Results: Spiral computed tomography was a valuable method for identifying 20 patients with pulmonary embolism (sensitivity, 100%). It could correctly exclude pulmonary embolism in 28 out of 30 non - pulmonary embolism cases yielding a specificity of 94%.In 10 of the 20 patients devoid of pulmonary embolism; Spiral computed tomography provided an alternate clinical diagnosis. In the remaining 10 patients, spiral computed tomographic angiography scans were normal. The statistical analysis of the computed tomography values standard deviation and signal-noise ratio of the pulmonary trunk and pulmonary artery (without right or left predilection) showed a p-value>0.05. D-dimer Test showed elevated levels in 18 patients who were diagnosed with pulmonary embolism on spiral computed tomography scans. 8 patients without pulmonary embolism on spiral computed tomography scans also showed elevated D-dimer levels. The remaining 22 patients had normal D-dimer levels. Conclusion: Spiral computed tomography has a good sensitivity and specificity for the diagnosis of pulmonary embolism. In the majority of patients who did not have pulmonary embolism, it provided important ancillary information for the final diagnosis. Therefore, combining Spiral computed tomography scan with a D-dimer Test is more effective in the accurate diagnosis of pulmonary embolism.