| [Background] Pulmonary embolism (PE) is a common disorder with considerable morbidity, high rate of misdiagnosis and missed diagnosis, and mortality, Given quick diagnosis and proper treatment , the morbidity can be reduced greatly. There are no reliable clinical features or specific laboratory tests for PE, and the diagnosis depends on imaging findings. Spiral CT angiography is a minimally invasive technique, it has shown great promise for diagnosing central PE. The objective of our research is to assess prospectively the effectiveness of spiral CT in the diagnosis of PE, based on noninvasive imaging examinations. And to detect every PE features on CTPA, to expound the role of CTPA in follow-up.Part I Diagnostic Value of Spiral CT Angiography for Plumonary Embolism[Objective] To assess prospectively the diagnostic value of spiral CT in the diagnosis of PE, including sensitivity, specificity, positive and negative predictive values. And to compare the diagnostic value of CTPA with perfusion scintigraphy. [Materials and Methods] CTPA was performed in 100 patients who wereclinically suspected of having PE. Other noninvasive imaging examinations included perfusion scintigraphy(n=84), lower extremities imaging modalities for deep venous thrombosis(DVT)(n=50) and plain film(n=92). The GE HiSpeed CT/i was used.The pulmonary arteries were mominated according to Boyden nomenclature. All images were analyzed independently by two radiologists on workstation. The patients were categorized as high, intermediate, or low possibility of PE based on clinical data and laboratory tests.The diagnosis of PE based on two noninvasive imaging examinations with positive findings and excluded by negative findings of two ndninvasive imaging examinations(including CTPA, perfusion scintigraphy, lower extremities imaging modalities for DVT). The imerval of different noninvasive imaging modalities was less than 24h to 48h. On CTPA, the diagnosis of PE was made when filling defect was detected in the pulmonary artery.The negative diagnosis was made when there no any abnormal signs on excellent medium infusioned-CTAP.The PIOPED standard was used for diagnosing PE on scintigraphy.DVT was determined based on the standard of Chinese Medical Academy. According to the order of pulmonary branch affected with embolus, we classified PE into central and peripheral type. Difference in the diagnostic valu-? between perfusion scintigraphy and CTPA was assessed with the Kappa test. Statistical significance was defined at the 0.05 level. [Results] Clinical probability of PE was categorized as low (n=13), indeterminate(n=27) and high (n=60). Based on the standard, 68 cases were diagnosed as PE, 29 patients were excluded PE, the other three had unsatisfactory CTPA examinations, and were excluded from our study. 65 and 29 cases were correctly diagnosed and excluded PE with .CTPA, respectively. 62 cases were central type, and the other three were peripheral. The sensitivity, specificity, accuracy, positive and negative predictive values of CTPA were 95.59? 96.91%> 100.00% and 90.63% respectively. As to the 81cases with both CTPA and perfusion scintigraphy, And the sensitivities and specificities of CTPA and perfusion scintigraphy were 94.83%/100.00% and 91.23%/79.17%, respectively. And the efficacy of CTPA was significantly superior to that of perfusion scintigraphy( k=0.701 , x2=28.50, ?<0.005). For 47 cases with both CTPA and lower extremity deep vein imaging , 32 patients were dignosed as PE according to the standard. Positive findings were detected in 28 cases(87.5%). Compared to CTAP, the consistence diagnosing rate of DVT imaging was 85.11%(40/47). 89 patients were examined with both plain film and CTPA. The sensitivity and specificity of indirect signs on plain films to suggest PE were quite low(29.31%,70.97%). [Conclusion] CTPA can diagnose PE accurately with high sensitivity and high specificity, and the clinical efficacy is significantly superior to the perfusion scintigraphy, so CTPA can be used as the first imaging mod... |
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