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Aortic Endograft Surveillance: Use of Fast-Switch kVp Dual-Energy Computed Tomography With Virtual Noncontrast Imaging

Maturen, Katherine E. MD*; Kleaveland, Patricia A. MD*; Kaza, Ravi K. MD*; Liu, Peter S. MD*; Quint, Leslie E. MD*; Khalatbari, Shokoufeh H. MS; Platt, Joel F. MD*

Journal of Computer Assisted Tomography: November/December 2011 - Volume 35 - Issue 6 - p 742–746
doi: 10.1097/RCT.0b013e3182372c14
Original Article

Objective: To assess endoleak detection and patients’ radiation exposure using fast-switch peak kilovoltage (kVp) dual-energy computed tomography (DECT) with virtual noncontrast (VNC) imaging.

Methods: Institutional review board approved retrospective review of triphasic CTs for endograft follow-up: single-energy true noncontrast (TNC) and dual-energy arterial- and venous-phase postcontrast scans on GE HD-750 64-detector scanners. Iodine-subtracted VNC images generated from dual-energy data. Two radiologists (VNC readers) independently performed 2 reading sessions without TNC images: (1) arterial and VNC and (2) venous and VNC. Interrater agreement, leak detection sensitivity, and dose estimates were calculated.

Results: Original dictations described 24 endoleaks in 78 scans. Virtual noncontrast reader agreement was high (κ = 0.78–0.79). Virtual noncontrast reader ranges for sensitivity and negative predictive value for leak detection were 87.5% to 95.8% and 94.0% to 98.0% in venous phase. Dose reduction estimate was 40% by eliminating one phase and 64% by eliminating 2 phases of imaging.

Conclusion: Virtual noncontrast images from fast-switch peak kilovoltage DECT data can substitute for TNC imaging in the postendograft aorta, conferring substantial dose reduction. Eliminating 1 of 2 postcontrast phases further reduces dose, with greater negative predictive value for leak detection in the venous versus the arterial phase. Thus, the use of a monophasic venous-phase DECT with VNC images is suggested for long-term endograft surveillance in stable patients.

From the *Department of Radiology, University of Michigan Hospitals, Ann Arbor; and †Michigan Institute of Clinical and Health Research, Ann Arbor, MI.

Received for publication June 1, 2011; accepted September 12, 2011.

Reprints: Katherine E. Maturen, MD, University of Michigan, Ann Arbor, MI (e-mail: kmaturen@umich.edu).

Statistical analysis was performed with financial support from grant UL1RR024986.

The authors report no conflicts of interest.

© 2011 Lippincott Williams & Wilkins, Inc.