Helical CT as preferred imaging modality in the diagnosis of pulmonary embolism]

PURPOSE: We investigated the role of Helical Computed Tomography (CT) as primary screening imaging modality in the diagnosis of pulmonary embolic disease. MATERIAL AND METHODS: We retrospectively reviewed the CT examinations, resulted positive for pulmonary embolism, performed in 134 patients (69 men and 65 women, ranging in age 23-83 years) from June 1998 to June 1999. CT was performed with a helical unit (thickness 3 mm, reconstruction interval 2 mm, pitch 1.5) after intravenous contrast agent (120 mL) rapid infusion (4 mL/s, 15s acquisition delay from bolus starting) and using a power injector. The spiral acquisition was performed from the apex of the pulmonary trunk to the diaphragm. Pulmonary embolism was considered as complete when a filling defect was present in a main pulmonary artery, as moderate when a filling defect was observed in an interlobar pulmonary artery and as very small when a filling defect was identified in a segmental pulmonary artery. RESULTS: Helical CT allowed us to identify the presence of a filling defect in the main pulmonary artery in 60.4% of cases (complete pulmonary embolism), in an interlobar pulmonary artery in 27.6% of cases (moderate pulmonary embolism) and in a segmental pulmonary artery in 11.9% of cases (very small pulmonary embolism). At helical CT study, pulmonary embolus was identified as complete filling defect (92.5% of cases), thromboembolic mass floating freely in the lumen (28.3%) and partial filling defect (19.4%). Pleural effusion and pulmonary infarction were associated in 46.2% and 20.1% respectively. DISCUSSION AND CONCLUSIONS: Pulmonary embolic disease continues to be a major cause of morbidity and mortality. The clinical diagnosis of pulmonary embolism remains an important challenge: among the different imaging modalities, contrast-enhanced helical CT can be used as primary screening imaging modality in the diagnosis of pulmonary embolism, allowing us to detect the presence of pulmonary embolus in the main, lobar and segmental artery, as demonstrated in our experience.