MDCT overtakes ventilation-perfusion lung scan for diagnosing pulmonary embolism

May 17 2005

MDCT pulmonary angiography is replacing the ventilation-perfusion lung scan to diagnose suspected pulmonary embolism in hospitalized patients, say researchers from Rhode Island Hospital in Providence.

MDCT pulmonary angiography is a state-of-the-art CT examination that images the pulmonary arteries after IV injection of iodinated contrast material. Ventilation-perfusion lung scintigraphy is an older examination that is performed through the IV injection of a radiopharmaceutical and the inhalation of a radioactive gas.

For the study, the researchers reviewed the results of all ventilation-perfusion scans and MDCT pulmonary angiograms during a 30-month period at their hospital. The researchers found that the average number of ventilation-perfusion scans dropped from 5.7 to 3.6 per month and the average number of MDCT pulmonary angiograms increased from 21.9 to 42.5 per month.

“The exact degree of the changes in our study is only representative of our institution; however, the shift towards diagnosing pulmonary embolism by CT is a national trend. Several other authors have also published similar findings from other hospitals,” said Jay H. Donohoo, MD, lead researcher of the study.

According to the researchers, there are a number of reasons for the shift toward MDCT pulmonary angiography. “The current generation of MDCT scanners can quickly image the pulmonary vasculature with high resolution, enabling small pulmonary emboli to be diagnosed more frequently and with greater confidence. In addition, other significant diagnoses such as aortic dissection, pneumothorax, rib fractures or cancer are seen with CT in up to 30% of patients with suspected pulmonary embolism. These other findings can't be made with a ventilation-perfusion scan,” said Dr. Donohoo. “MDCT has experienced rapid technological advancement over the last 15 years, while ventilation-perfusion lung scintigraphy has remained essentially unchanged,” he added.

“If a patient has chest pain and there is clinical suspicion for pulmonary embolism, they are more likely to have a CT performed today than a similar patient would have 15 years ago. Overall this probably results in better patient care because the presence or absence of pulmonary embolism and any other significant diagnoses are made in a more timely manner and appropriate treatment can be started sooner,” said Dr. Donohoo.

Dr. Donohoo will present the full results of the study on May 17 during the American Roentgen Ray Society Annual Meeting in New Orleans, LA.