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 As soon as a study is published, the technology the study used becomes outdated.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.
