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