Newer imaging technologies allow physicians to visualize more of the arteries in the lungs, including detecting small blood clots not previously seen, but seeing more may have little impact on the patient’s outcome, a new study suggests.
The study included 198 patients with suspected pulmonary embolism. About half of the patients (98) had a multidetector CT (MDCT) examination; 100 patients had a single-detector CT examination. The radiology examinations came back negative, and the patients did not undergo anticoagulant treatment.
MDCT is now more widely used to examine patients with suspected pulmonary embolism. It allows radiologists to see more of the arteries throughout the lungs, and to detect small clots in those arteries, said J. David Prologo, MD, chief radiology resident at University Hospitals of Cleveland and lead author of the study. However, “our study found no significant difference in the outcomes of patients ruled out for pulmonary embolism with MDCT vs. single-detector CT,” he said. “It is possible that we missed small clots in the patients that had a single-detector CT examination, but at three and six months, the outcomes were similar,” he said.
Seeing more can have drawbacks as well, Dr. Prologo said. “If we see the small clots, we’re more likely to treat them; and there are risks to anticoagulant therapy,” he said. In fact, “a recent study found a 10 times higher risk of hemorrhagic stroke in patients receiving oral anticoagulant therapy when compared to the general population,” Dr. Prologo said. It is imperative that “clinicians consider the risk-benefit ratio of therapy in patients with previously undetectable small clots in the peripheral pulmonary vasculature,” he added.
Dr. Prologo recommends a large-scale prospective randomized study to determine if patients with small clots need to undergo anticoagulation treatment. “Today a great many more patients are being evaluated for pulmonary emboli with scanners that can detect very small clots. This is likely to result in the discovery of many more patients with small clots who probably would not have been treated in the past and may have done fine. Improved technology is forcing us to face new clinical questions such as whether or not every small clot diagnosed with CT warrants the risks of treatment,” he said.
The study appears in the April 2005 issue of the American Journal of Roentgenology.