Digital Radiography: Computed Tomography Angiography (CTA), might be unnecessary for many patients suspected of having pulmonary embolism (PE), according to results of a new study published in the journal Radiology. The study based its suggestions on the results of PE risk assessment analysis. PE risk assessment could help in reducing radiation exposure and costs associated with CT angiography. "Our study suggests that the frequency of ordering CT angiograms can be markedly reduced with resultant cost-savings and decreased radiation exposure," said lead author Mark D. Mamlouk, M.D., radiology resident at the University of California, Irvine in Orange, Calif.
Despite the fact that CT angiography is the preferred modality for diagnosing PE, due to its high sensitivity and specificity, the increasing use of the examination has revealed concerns over procedure costs and radiation exposure to patients, in addition to the risks associated with the use of contrast agents. Researchers assessed in their study possibility of using risk factors associated with thromboembolism, or blood clot formation, to reduce the number of CT angiograms for PE. The study involved the revision of 2,003 electronic medical records of patients, who underwent CT angiography for possible PE, and the researchers took into their consideration the risk factors, including age, history of immobilization and cancer, excess estrogen state, the history of venous thromboembolism, gender and disorders that cause blood to clot more easily than normal. It was found that, in 1,806 patients (90.2% of all patients), CTA were negative for PE. While the 197 patients with positive CT angiograms positive for PE had one or more risk factors. Age of 65 or older and immobilization were the most common risk factors in positive PE patients.
According to Dr. Mamlouk “Without any thromboembolic risk factors, there was only a 0.95% chance of a CT angiogram positive for PE,” adding "Thromboembolic risk factor assessment is an effective clinical method to determine when to perform CT angiography for PE," Dr. Mamlouk said. "Risk assessment can be performed when clinicians acquire their patients' history. It takes only a few minutes, and there's no cost." It was also concluded that the combination of no risk factors and a negative D-dimer, a blood test that helps in the diagnosis of blood clots, yielded an extraordinarily low risk for a positive CT angiogram for PE. "Pulmonary Embolism at CT Angiography: Implications for Appropriateness, Cost, and Radiation Exposure in 2,003 Patients." said Dr. Mamlouk along with Eric vanSonnenberg, M.D., Rishi Gosalia, M.D., David Drachman, Ph.D., Daniel Gridley, M.D., Jesus G. Zamora, M.D., Giovanna Casola, M.D., and Sanford Ornstein, M.D.