A newer type of scan to detect potentially deadly blood clots in the lungs works as well as an older technique it has largely replaced, researchers said on Tuesday.

A Canadian team led by Dr. David Anderson of Dalhousie University in Halifax, Nova Scotia, said the study was the first to compare computed tomography or CT angiography with the older ventilation-perfusion scans.

The older scan uses radioactive material inhaled into the lungs and injected into the blood stream to help rule out blood clots in the lungs.

It has largely been replaced in recent years by the CT scan, which gives clearer positive or negative results despite concerns about whether it is as sensitive, said the report published in the Journal of the American Medical Association.

The researchers said the results were reassuring given earlier reports that the newer technology was less sensitive.

Blood clots in the lungs affect about 250,000 people in the United States each year and cause 5 to 10 percent of all deaths among hospital patients, the report said.

But the problem is one of the most difficult to diagnose, so that clot-busting therapy can be started quickly enough for only those who need it.

The study involved 1,417 patients observed between 2001 and 2005.

The researchers concluded the CT scan worked as well as the older technique "in ruling out pulmonary embolism."

At the same time, the CT scan found 5 percent more clots than the older technique, the study said, although whether this is significant will require a closer look.

In an editorial commenting on the study, Dr. Jeffrey Glassroth of the Feinberg School of Medicine at Northwestern University in Chicago said it "convincingly demonstrates" that the CT approach is not inferior to the older technique.

(Reporting by Michael Conlon; Editing by Julie Steenhuysen and John O'Callaghan)