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Diagnostic Accuracy of Computed Tomography Pulmonary Angiography With Reduced Radiation and Contrast Material Dose: A Prospective Randomized Clinical Trial

Szucs-Farkas, Zsolt MD*†; Christe, Andreas MD*; Megyeri, Boglarka MD; Rohacek, Martin MD§∥; Vock, Peter MD*; Nagy, Endre V. MD; Heverhagen, Johannes T. MD*; Schindera, Sebastian T. MD*#

doi: 10.1097/RLI.0000000000000016
Original Articles

Objective The objective of the study was to test the diagnostic performance of low-dose computed tomography pulmonary angiography (CTPA) at peak tube voltage of 80 kVp with both reduced radiation and reduced contrast material (CM) dose.

Materials and Methods In this single-center, single-blinded prospective randomized trial, 501 patients with body weights of less than 100 kg with suspected acute pulmonary embolism (PE) were assigned to normal-dose CTPA (100-kVp tube energy and 100-mL CM, 255 patients) and low-dose CTPA (80-kVp tube energy and 75-mL CM, 246 patients). Primary end points were evidence of PE in CTPA and accuracy of CTPA on a composite reference standard. Results were compared by calculating the odds ratio with the 95% confidence interval.

Results The reference diagnosis was equivocal in 20 of the 501 patients. Diagnosis of CTPA was correct in 240 patients and incorrect in 5 in the normal-dose group. Computed tomography pulmonary angiography was correct in 230 patients and incorrect in 6 in the low-dose group (odds ratio, 1.25; 95% confidence interval, 0.38–4.16; P = 0.77). Sensitivity was 96.9% and 100% and specificity was 98.1% and 97.1% in the normal-dose and low-dose groups, respectively. No PE or PE-related death occurred during the 90-day follow-up. The size-specific dose estimates were 30% lower at 80 kVp (4.8 ± 1.0 mGy) compared with that at 100 kVp (6.8 ± 1.2 mGy; P < 0.001).

Conclusions The accuracy of low-dose CTPA at 80 kVp with a 30% reduced radiation dose and a 25% lower CM volume is not significantly different from that of normal-dose CTPA at 100 kVp in detecting acute PE in patients weighing less than 100 kg.

Supplemental digital content is available in the text.

From the *University Institute of Diagnostic, Interventional and Paediatric Radiology, Inselspital, University Hospital Bern, Berne; †Institute of Radiology, Hospital Centre of Biel, Biel/Bienne, Switzerland; ‡Department of Anaesthesiology and Intensive Care, University of Debrecen, Health and Medical Science Centre, Debrecen, Hungary; §Department of Emergency Medicine, Inselspital, University Hospital Bern, Berne; ∥Department of Emergency Medicine, University Hospital Basel, Basel, Switzerland; ¶Department of Medicine, University of Debrecen, Health and Medical Science Centre, Debrecen, Hungary; and #Department of Radiology, University Hospital Basel, Basel, Switzerland.

Received for publication August 31, 2013; and accepted for publication, after revision, October 17, 2013.

Conflicts of interest and sources of funding: Supported by the Stanley Thomas Johnson Foundation (Project number 3790).

The authors had no contractual obligations toward this foundation; they are neither its employees nor its consultants.

The authors report no conflicts of interest.

Supplemental digital contents are available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (

Reprints: Zsolt Szucs-Farkas, MD, Institute of Radiology, Hospital Centre of Biel, Vogelsang 84, Biel/Bienne, CH-2501 Switzerland. E-mail:

© 2014 by Lippincott Williams & Wilkins