BACKGROUND AND PURPOSE: To our knowledge, there has been no study that compares the radiation dose delivered to the eye lens by 16-and 64-section multidetector CT (MDCT) for standard clinical neuroimaging protocols. Our aim was to assess radiation-dose differences between 16-and 64-section MDCT from the same manufacturer, by using near-identical neuroimaging protocols.
Objective:To evaluate what specific combination of clinical criteria and d-dimer values may yield at least a 10% positive pulmonary embolism (PE) rate in patients undergoing pulmonary CT angiography (CTA). Materials and Methods: Retrospective review of all patients presenting to the Emergency Department with possible PE who underwent pulmonary CTA and had a d-dimer drawn. Wells scores were retrospectively assigned based on data gathered through medical records. Results: During a 29-month period, 1110 patients underwent pulmonary CTA. Of these, 773 also had a d-dimer drawn. These subjects were stratified based on serum d-dimer levels into negative (≤4 µg/ml), nonpositive (0.41 -1.0 µg/ml), or positive (>1.0 µg/ml) d-dimer categories. The prevalence of positive CTA studies was >10% only in the positive d-dimer group. Subjects were also stratified based on their Wells score into three clinical categories: low (score < 2), intermediate (score = 2 -6), and high risk of pulmonary embolism (score > 6). The prevalence of positive CTA was > 10% only in the group of subjects with high clinical risk. When stratified according to both Wells criteria and d-dimer, only those patients with intermediate or high clinical risk combined with a positive d-dimer (>1.0 µg/ml) had a prevalence of positive pulmonary CTA > 10%. By limiting the use of CTA studies to those patients with positive d-dimer values or high clinical risk, 438 (55.4%) patients could have avoided CTA imaging. Conclusion: Utilizing CTA only in patients suspected of PE with a combination of high clinical risk based on a Wells criteria threshold score > 6 and a serum d-dimer cutoff of 1 µg/ml would increase the prevalence of positive pulmonary CTA studies above 10% and avoid a large number of CTA imaging studies.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.