Thoracic aorta: prospective electrocardiographically triggered CT angiography with dual-source CT--feasibility, image quality, and dose reduction.
OBJECTIVE
To prospectively investigate the feasibility, image quality, and radiation dose for prospective electrocardiographically (ECG) triggered sequential dual-source computed tomographic (CT) angiography of the thoracic aorta in comparison to retrospective ECG-gated helical dual-source CT angiography.


METHODS
This study was approved by the institutional review board; informed consent was obtained. One hundred thirty-nine patients referred for ECG-assisted dual-source CT angiography of the thoracic aorta were prospectively enrolled. Inclusion criteria were stable sinus rhythm and heart rate of 80 beats per minute or less. Tube voltage was adjusted to body mass index (< 25.0 kg/m(2), 100 kV, n = 58; > or = 25.0 kg/m(2), 120 kV, n = 81). In both cohorts, patients were randomly assigned to prospective or retrospective ECG-assisted data acquisition. In both groups, tube current (250 mAs per rotation) was centered at 70% of the R-R cycle. The presence of motion or stair-step artifacts of the thoracic aorta was independently assessed by two readers. Effective radiation dose was calculated from the dose-length product.


RESULTS
Subjective scoring of motion and stair-step artifacts was equivalent for both techniques. Scan length was not significantly different (23.8 cm +/- 2.4 [standard deviation] vs 23.7 cm +/- 2.5 for prospective and retrospective ECG-triggered CT angiography, respectively; P = .54). Scanning time was significantly longer for prospective ECG-triggered CT angiography (18.8 seconds +/- 3.4 vs 16.4 seconds +/- 3.3, P < .001). Mean estimated effective dose was significantly lower for prospective data acquisition (100 kV, 1.9 mSv +/- 0.5 vs 4.1 mSv +/- 0.7, P < .001; 120 kV, 5.3 mSv +/- 1.1 vs 9.5 mSv +/- 3.0, P < .001).


CONCLUSIONS
Prospective ECG-gated sequential dual-source CT angiography of the thoracic aorta is feasible, despite the slightly longer acquisition time. Thus, motion-free imaging of the thoracic aorta is possible at significantly lower radiation exposure than retrospective ECG-gated helical dual-source CT angiography in certain patients with a regular heart rate.
Department of Diagnostic Radiology, University Hospital Freiburg, Hugstetter Strasse 55, 79104 Freiburg, Germany. philipp.blanke@uniklinik-freiburg.de
Philipp
P
Blanke
Stefan
S
Bulla
Tobias
T
Baumann
Matthias
M
Siepe
Jan Thorsten
JT
Winterer
Wulf
W
Euringer
Arnd-Oliver
AO
Schäfer
Elmar
E
Kotter
Mathias
M
Langer
Gregor
G
Pache
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001013:Aorta, Thoracic / Q000000981:diagnostic imaging*; D001018:Aortic Diseases / Q000000981:diagnostic imaging*; D016477:Artifacts; D017023:Coronary Angiography / Q000379:methods*; D004562:Electrocardiography; D005240:Feasibility Studies; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011829:Radiation Dosage; D011857:Radiographic Image Interpretation, Computer-Assisted; D018709:Statistics, Nonparametric; D036542:Tomography, Spiral Computed; D014057:Tomography, X-Ray Computed / Q000379:methods*