Objective: To compare prospectively ECG gated CT pulmonary angiography (CTPA) with routine helical ungated CTPA for cardiac-related motion artifacts and for effective radiation dose. Subjects and Methods: Twenty patients with signs and symptoms suspicious for pulmonary embolism who had a heart rate below 85 were scanned with prospectively ECG gated CTPA. These exams were matched for several clinical parameters to exams from twenty similar clinical patients scanned with routine ungated helical CTPA. Three blinded independent reviewers subjectively evaluated all exams for overall pulmonary artery enhancement and for several cardiac motion related artifacts, including vessel blurring, intravascular shading, and double line. Reviewers also measured pulmonary artery intravascular density and image noise. Patient radiation effective dose for each technique was compared. Fourteen clinical prospectively gated CTPA exams from a second institution were evaluated for the same parameters. Results: Prospectively ECG gated CTPA resulted in significantly decreased motion-related image artifact scores in lung segments adjacent to the heart compared to ungated CTPA. While measured image noise was not significantly different between the two types of CTPA exams, measured pulmonary artery density was significantly greater in the ECG gated exams. Effective dose was 28% less for prospectively ECG gated CTPA (4.9 mSv versus 6.8 mSv, p=0.02). Similar results were found in the prospectively ECG gated exams from the second institution. Conclusion: Compared to routine helical ungated CTPA, prospectively ECG gated CTPA may result in less subjective cardiac motion artifact in lung segments adjacent to the heart and significantly less patient radiation dose.
Available at: http://works.bepress.com/kent_koprowicz/22/