Description of Treatment/Procedure

Computed tomography (CT) has been used in the diagnosis of pulmonary embolism (PE) since 1975. Developments in CT technology have reduced the scan times and interscan delays with a subsequent improvement in image quality. The "gold standard" for PE diagnosis is pulmonary angiography (PA). However, PA is an invasive procedure. Since only about one-third of patients with suspected PE actually have PE and anticoagulant use (the generally accepted treatment) is not without risk, there is a need for an accurate, less-invasive diagnostic tool. Also, helical CT is increasingly being used as the initial diagnostic procedure or as a follow-up to a nondiagnostic V/Q scan.

Committee Summary

With regard to the use of contrast-enhanced helical computed tomography (CT) for the diagnosis of pulmonary embolism (PE), the ICSI Technology Assessment Committee finds:

1. All forms of CT are safe.
   
2. Conventional CT is not indicated in the diagnosis of PE.
   
3. Contrast-enhanced helical CT has good diagnostic accuracy (sensitivity of 70% to 100%; specificity of 78% to 97%) and higher sensitivity and interobserver agreement than V/Q scanning. Reported accuracies are highly dependent on proper technique and accurate assessment by experienced radiologists.
   
4. Compared to PA and V/Q scanning, the reduced time required for and less invasive nature of contrast-enhanced helical CT would appear to be beneficial for the critically ill patient. For institutions with 24-hour expert interpretation of contrast-enhanced helical CT, full time access to helical CT may provide an advantage over other techniques.
   
5. Information from CT led to alternative diagnoses in over 50% of patients (Conclusion Grade II).