Abdominal aortic aneurysm: can the arterial phase at CT evaluation after endovascular repair be eliminated to reduce radiation dose?
OBJECTIVE
To retrospectively determine if arterial phase computed tomographic (CT) imaging is necessary for follow-up imaging of patients who have undergone endovascular stent-graft therapy for abdominal aortic aneurysm.


METHODS
This HIPAA-compliant study was exempt from institutional review board approval; informed patient consent was waived. Eighty-five patients (66 men, 19 women; mean age, 66 years; range, 45-81 years) underwent 110 multidetector CT examinations after endovascular repair of abdominal aortic aneurysms. Nonenhanced CT images were obtained. Intravenous contrast material was then injected at 4 mL/sec, and arterial and venous phase (60 seconds) CT images were obtained. The nonenhanced and venous phase images were evaluated to determine if an endoleak was present. Subsequently, arterial phase images were analyzed. The effective dose was calculated. Ninety-five percent confidence intervals as indicators of how often arterial phase imaging would contribute to the diagnosis of endoleak were determined.


RESULTS
Twenty-eight type II endoleaks were detected by using combined nonenhanced and venous phase acquisitions. Twenty-five of the 28 endoleaks were also visualized during the arterial phase. Three type II endoleaks were seen only during the venous phase. The arterial phase images depicted no additional endoleaks. Seventy-eight CT examinations performed in 67 patients revealed no endoleak during the venous phase. The arterial phase images also depicted no endoleaks at these examinations. Thus, for no more than 3.1% of all examinations, there was 95% confidence that arterial phase imaging would depict an endoleak missed at venous phase imaging. Arterial phase imaging contributed to a mean of 36.5% of the effective dose delivered.


CONCLUSIONS
Study results indicate that arterial phase imaging may not be necessary for the routine detection of endoleaks. Radiation exposure can be decreased by eliminating this phase.
Macari
Michael
M
Department of Radiology, New York University School of Medicine, Suite HW 211, 560 First Ave, New York, NY 10016, USA. michael.macari@med.nyu.edu
Chandarana
Hersh
H
Schmidt
Bernhardt
B
Lee
Julie
J
Lamparello
Patrick
P
Babb
James
J
D000368:Aged; D000369:Aged, 80 and over; D017544:Aortic Aneurysm, Abdominal / Q000000981:diagnostic imaging / Q000628:therapy*; D019917:Blood Vessel Prosthesis Implantation; D003287:Contrast Media / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007472:Iohexol / Q000008:administration & dosage / Q000031:analogs & derivatives; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011829:Radiation Dosage; D012189:Retrospective Studies; D015607:Stents; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
D003287:Contrast Media; D007472:Iohexol; C038192:iopromide