CT (computed tomography) venography boosts blood clot detection:

Recurring blood clots in the lungs could be prevented by conducting computed tomography (CT) scans of the legs, according to a study published in Radiology (February 2005). US researchers from the Presbyterian Hospital-Weill Medical College at Cornell University, New York, found that adding indirect CT venography (CTV) to CT pulmonary angiography (CTPA) - a common type of lung scan - improved the detection of thromboembolic disease by up 20%. The authors said the use of CTV following CTPA required no additional contrast agent and takes only three minutes to perform. Most pulmonary emboli occur when a blood clot in the leg breaks free and travels to the lung, the study said.