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Pulmonary CTA Sensitivity and PIOPED II
The publication of PIOPED II has led some to doubt the sensitivity of pulmonary CTA for pulmonary embolism. This study reported an overall sensitivity of 83% which could be increased to nearly 90% with the addition of CTV (CT Venography). 83% is a horrible sensitivity. So, why should you care?
- This study used 16 detector CTs...not the 64+ head scanners we are now using. This study, like many others, suffers from the explosion of CT technology. As soon as a study is published, the technology the study used becomes outdated. Most studies now look at OUTCOME...i.e., what % of patients with a negative CT who do not receive anticoagulation develop a PE at 30, 60, 90 days? Current literature shows that the chances of VTE at 90 days for patients with negative CTAs is less than 2%.
- Bottom line, don't be too discouraged by the PIOPED II study. In addition, many of the authors of the study actually advocate for CTA/CTV to rule out PE. This is a tremendous amount of radiation and has NOT been validated as a "standard" approach to ruling out PE.
- Lastly, it is generally a good idea to try to limit the use of CT scans (yes, that is what I said) by using a d-dimer/pretest probability or PERC/clinical gestalt approach. This is a defensible strategy.