The role of helical CT in the diagnosis of pulmonary embolism.

Diagnosing pulmonary embolism is problematic since clinical signs and symptoms of PE are aspecific. Diagnostic algorithms have been developed to rationalize the use of imaging tests in patients with a clinical suspicion of PE. An algorithm based on helical CT has gained widespread interest due to the availability of helical CT. However, these algorithms have often been implemented without appropriate assessment in clinical practice. If one is to implement helical CT as a first line diagnostic test for patients with clinically suspected pulmonary embolism it is important to note that a) CT is sensitive to larger emboli b) single slice technology may miss smaller subsegmental pulmonary emboli and c) outcome studies using a combination of normal single slice helical CT and normal compression ultrasonography rules out safely pulmonary embolism. In view of recent developments in multi row detector CT technology, large, well-designed studies are needed to determine the exact role of multi row helical CT in diagnosing PE.