Improving detection of venous thromboembolism. New technology holds promise for early, precise diagnosis

In recent years, a number of modalities have been evaluated for the diagnosis of venous thromboembolism. The role of these modalities is still evolving. While ventilation-perfusion scanning is important in the diagnosis of venous thromboembolism, spiral CT scanning, MRI, and D-dimer assays are now being used more often, either exclusively or in combination with ventilation-perfusion scanning. A number of diagnostic algorithms using these modalities are currently being evaluated. Regardless of which diagnostic approach is used, the clinician must be aware of some key limitations. Spiral CT scanning has gained popularity because it is noninvasive and can rapidly identify other cardiopulmonary diseases that mimic pulmonary embolism. Its use has been limited because of its inability to detect subsegmental pulmonary emboli. D-dimer assays offer promise as rapid, inexpensive screening tools. However, the wide variability in assay performance has limited its usefulness. We recommend that if D-dimer assays are to be used in a diagnostic algorithm, the clinician be aware of the details of the assay. At present, lack of data precludes use of MRI as a primary diagnostic tool for detection of venous thromboembolism.