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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.