Have an account? Please log in.
Text size: Small font Default font Larger font
Radiology Daily
Radiology Daily PracticalReviews.com Radiology Daily

CT ‘Too Good’ At Finding Pulmonary Emboli

  • Comments

Well, this is quite a provocative title: “When a test is too good: how CT pulmonary angiograms find pulmonary emboli that do not need to be found.”

That’s the headline atop an article published online last week in BMJ. The authors are affiliated with the U.S. Department of Veterans Affairs’ Center for Health Quality, Outcomes and Economic Research in Bedford, Massachusetts, and the Dartmouth Institute for Health Policy and Clinical Practice in Lebanon, New Hampshire.

Lead author Renda Soylemez Wiener, MD, an assistant professor of medicine at Boston University School of Medicine, is affiliated with both the VA center and the Dartmouth Institute. She and her colleagues reviewed existing literature. They found that CT scans have overwhelmingly replaced ventilation-perfusion (VQ) scanning as the main test when pulmonary embolism is suspected. The reason is simple: CT yields much better images.

The report states:

Clinicians like CT pulmonary angiography because it allows them to find causes besides pulmonary embolism to explain non-specific symptoms (such as pleural effusion or pneumonia).

However, the researchers say that many of the smaller emboli that CT detects are no threat to the patient, and that treating those small emboli causes more harm than good.

Doctors have embraced CT, the writers say, for several reasons:

  • They don’t want to miss “a silent killer.”
  • “Radiologists like CT pulmonary angiography because they can make definitive diagnoses more readily than with VQ scans.”
  • Doctors fear malpractice suits if they don’t order the most respected test.
  • Owners of expensive scanners want to keep the machines busy to generate revenue.
  • Companies that make anticoagulant drugs have encouraged patients to ask about testing.

The authors say that in the eight years after CT pulmonary angiography was introduced (1998–2006), the age-adjusted incidence of pulmonary embolism increased by 80 percent after having remained stable the previous five years. During those same eight years, age-adjusted mortality in the U.S. population from pulmonary embolism changed little, going from 12.3 to 11.9 per 100,000. But in-hospital deaths from pulmonary embolism decreased from 12.1 percent to 7.8 percent, “suggesting that the extra pulmonary emboli being detected are less lethal (given that treatment has not become more effective).”

The writers advocate using Wells scores and D-dimer testing to rule out imaging of some low-risk patients. And they suggest going back to ventilation-perfusion scanning for patients who are younger, have normal lungs, or have renal dysfunction.

BMJ says the article is the first in a series about overdiagnosis resulting from expanding definitions of disease and increasing use of new technology. It will be interesting to see how influential this article, and the rest of the series, prove to be.

* * *

The Affordable Care Act has experts predicting a boom in ultrasound. Find out why on our Facebook page.

Related CME seminar (up to 26.75 AMA PRA Category 1 credits™): Thoracic Imaging


Permalink: http://www.radiologydaily.com/?p=11230


  • No Related Posts
  • Comments

Would you like to keep current with radiological news and information?

Post Your Comments and Responses

Comments are closed.