New Technique Detects Deep Vein Thrombosis

Radiologists in Nottingham have discovered a fast and accurate technique to diagnose deep vein thrombosis (DVT), which may be particularly helpful to pregnant women and travellers at risk of developing dangerous blood clots.

In a study funded by the British Heart Foundation and published this week in the American journal, the Annals of Internal Medicine, (15 January 2002, volume 136, number 2) Professor Alan Moody and his team in the department of academic radiology at the University of Nottingham used magnetic resonance direct thrombus imaging (MRDTI) to visualize DVT in the legs. One hundred and one patients with suspected DVT, aged between 20 and 95 years, took part in the research to determine the accuracy of MRDTI to diagnose DVT above and below the knee. The results were compared with conventional tests and interpreted by two experts who found that the MRDTI diagnosis was accurate throughout the lower leg venous system.

?The great advantages that MRDTI has over other methods to detect thrombosis are that it is non-invasive, quick and reliable,? said Professor Moody. The scan takes about 12 minutes. Although venography, whereby a catheter is inserted into the veins, has largely been replaced by ultrasound, both techniques rely on changes secondary to a blood clot such as impaired blood flow. These results may be inconclusive. MRDTI is unique because it directly reveals the thrombus ? or clot ? in the legs.

MRDTI is highly sensitive and enables radiologists to pick up the disorder at an early stage even before symptoms are apparent. Action can then be taken to prevent the clot becoming larger and blocking the blood vessel, or the clot breaking off and travelling to the lungs and causing pulmonary embolism. It is well-tolerated by the patient who need not go through a range of tests to rule out DVT.

Although the study did not include pregnant women, Professor Moody is confident that MRDTI could play an important role in monitoring blood clot formation. ?DVT can be a major problem during pregnancy and in a few cases may be fatal,? he said. The clots often originate in the pelvis, which are difficult to detect using ultrasound. ?MRDTI produces good images of the pelvis and the pregnant mum would not need x-rays for us to see the blood vessels.?

DVT in travellers during long-haul flights causes great concern and the speed and reliability of MRDTI could, in the future, identify those most at risk. This will be the focus of Professor Moody?s next phase of research. “This emphasises the need for continued research to determine how it might be possible to prevent DVT so that the best available information can be passed on to the public.”

Professor Sir Charles George, medical director of the British Heart Foundation said, ?This is an important development arising from a highly skilled team of researchers. In our quest to reduce the risk of death from heart and circulatory disorders, Professor Moody?s results could have wide implications.?

Currently, there is limited availability of scanners, but as they become more plentiful and scanning speed increases, the technique will become cost-effective. Professor Moody concluded, ?We believe the future application of MRDTI will be enormously valuable in the early diagnosis and monitoring of DVT. This technology potentially could help protect people at risk of a life-threatening venous thrombosis as well as reassuring those who are not in danger?