Diagnostic accuracy of computed tomography pulmonary angiography with reduced radiation and contrast material dose: a prospective randomized clinical trial.
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.


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.
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.
Zsolt
Z
Szucs-Farkas
Andreas
A
Christe
Boglarka
B
Megyeri
Martin
M
Rohacek
Peter
P
Vock
Endre V
EV
Nagy
Johannes T
JT
Heverhagen
Sebastian T
ST
Schindera
D000792:Angiography / Q000379:methods*; D003287:Contrast Media / Q000008:administration & dosage; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives*; D008297:Male; D008875:Middle Aged; D015588:Observer Variation; D011446:Prospective Studies; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D011835:Radiation Protection / Q000379:methods*; D011856:Radiographic Image Enhancement / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016037:Single-Blind Method; D014057:Tomography, X-Ray Computed / Q000379:methods*
D003287:Contrast Media; C093233:iobitridol; D007472:Iohexol