Chest radiographs (CRs) have been used as a first-line examination for the evaluation of various thoracic diseases worldwide.^1,2 In fact, CR is the most commonly performed radiologic examination today, accounting for up to 26% of all diagnostic radiologic examinations.³ Interpretation of CR, however, remains a challenging task requiring both experience and expertise, as various anatomic structures can overlap in a single 2-dimensional image, and various physiological and pathological changes may appear similar or a single pathology may exhibit various features.⁴ Thus, interpretation is prone to errors, with a previous study⁵ reporting that 22% of all errors in diagnostic radiology were made in CRs. Compounding this difficulty is an increase in the number of examinations at a rate much faster than the increase in the number of qualified radiologists, which has led to an increased workload for radiologists.⁶

Venous thromboembolism (VTE), including pulmonary embolism (PE) and deep venous thrombosis (DVT), is a common and severe complication of critical illness. Although well documented in the general population, the prevalence of PE is less known in the ICU, where it is more difficult to diagnose and to treat. Critically ill patients are at high risk of VTE because they combine both general risk factors together with specific ICU risk factors of VTE, like sedation, immobilization, vasopressors or central venous catheter. Compression ultrasonography and computed tomography (CT) scan are the primary tools to diagnose DVT and PE, respectively, in the ICU. CT scan, as well as transesophageal echography, are good for evaluating the severity of PE. Thromboprophylaxis is needed in all ICU patients, mainly with low molecular weight heparin, such as fragmine, which can be used even in cases of non-severe renal failure. Mechanical thromboprophylaxis has to be used if anticoagulation is not possible. Nevertheless, VTE can occur despite well-conducted thromboprophylaxis.

To assess prospectively the clinical effectiveness of helical computed tomography (CT) in the evaluation of patients with unresolved suspicion for pulmonary embolism (PE). Helical CT was performed in 164 consecutive patients suspected of having acute PE, intermediate probability at ventilation-perfusion (V-P) scintigraphy, and normal findings at duplex ultrasonography (US) of the legs. Fifteen patients also underwent pulmonary angiography. Helical CT results were analyzed immediately to help plan anticoagulant treatment. If helical CT did not show PE, anticoagulant treatment was not indicated. Clinical outcome for these patients was assessed during 3-month follow-up. In 40 (24.4%) of 164 patients, the diagnosis of PE was based on results at helical CT (n = 39) or pulmonary angiography (n = 1). Repeated Doppler US of the legs depicted one thrombus in the calf of three patients with normal results at helical CT that could have been responsible for PE. During 3-month follow-up, three patients experienced recurrent PE (one death, two recurrences). Therefore, PE occurred in six (5.4% [95% confidence interval, 1.3%, 9.7%]) of 112 patients with normal findings at helical CT who did not receive anticoagulant treatment. Findings at helical CT allowed accurate diagnosis of acute PE in patients with intermediate probability at V-P scintigraphy and without deep venous thrombosis at duplex sonography of the legs.