The objective of this prospective study was to evaluate the sensitivity, specificity, positive and negative predictive values, and interobserver agreement in the diagnosis of pulmonary embolism with helical CT, compared with pulmonary angiography, for both global results and for selective vascular territories. Helical CT and pulmonary angiography were performed on 66 consecutive patients with clinical suspicion of pulmonary embolism. The exams were blindly interpreted by a vascular radiologist and by two independent thoracic radiologists. Results were analyzed for the final diagnosis as well as separately for 20 different arterial territories in each patient. Pulmonary angiography revealed embolism in 25 patients (38%); 48% were main, 28% lobar, 16% segmental, and 8% subsegmental. The sensitivity, specificity, and positive and negative predictive values of helical CT for observer 1 were, respectively, 91, 81.5, 75, and 94%; in 7.5% of the patients the exam was considered indeterminate. For observer 2 the values were, respectively, 88, 86, 81.5, and 91%; in 9% of the patients the exam was considered indeterminate. Main arteries were considered as non-valuable in 0-0.8%, the lobar in 1.5%, the segmental in 7.5-8.5%, and the subsegmental in 55-60%. Interobserver agreement for the final diagnosis was 80% (kappa 0.65). For each vascular territory, this was 98% (kappa 0.91) for main arteries, 92% (kappa 0.78) for lobar arteries, 79% (kappa 0.56) for segmental arteries, and 59% (kappa 0.21) for subsegmental arteries. Helical CT is a reliable method for pulmonary embolism diagnosis, with good interobserver agreement for main, lobar, and segmental territories. Worse results are found for subsegmental arteries, with high incidence of non-valuable branches and poor interobserver agreement.

No abstract

Background: Helical computed tomography has been introduced for the diagnosis of pulmonary embolism. Objective: To determine the clinical safety of withholding anticoagulant treatment in patients with suspicion of pulmonary embolism and negative helical computed tomography study. Methods: During a 9-month period, we performed a prospective study including 209 consecutive patients who underwent helical computed tomography for clinical suspicion of pulmonary embolism. In 53 patients (25.5%), helical computed tomography was diagnostic for pulmonary embolism, and in 24 patients (11.5%) it was indeterminate. In 132 patients (63%), the examination was negative for pulmonary embolism and no anticoagulation treatment was given. A clinical 3-month follow-up was carried out. During this period, 29 patients (22%) were excluded because anticoagulation therapy was initiated for other reasons, or because other diagnostic techniques were performed for pulmonary embolism. Four patients were lost in the 3-month period. In the end, 99 patients (75%) were included in the clinical follow-up. Results: Out of the 99 patients, 9 (9%) died during the 9-month follow-up, the cause of death in each case was not due to thromboembolic venous disease. No venous thromboembolic events were detected in the other 90 patients. Negative predictive value of helical computed tomography for pulmonary embolism was 99.09% (95% CI, 95.03–99.97%). Conclusions: In patients with clinical suspicion of pulmonary embolism and initial negative helical computed tomography from whom anticoagulants are withheld, no thromboembolic disease was detected in a 3-month follow-up. We consider helical computed tomography an effective method for ruling out pulmonary embolism as well as a front-line tool for diagnosis.

No abstract