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Single-Acquisition Dual-Energy Multidetector Computed Tomography: Analysis of Vascular Enhancement and Postprocessing Techniques for Evaluating the Thoracic Aorta

Godoy, Myrna C.B. MD; Naidich, David P. MD; Marchiori, Edson MD, PhD; Leidecker, Christianne PhD; Schmidt, Bernhard PhD; Assadourian, Bernard BSc; Vlahos, Ioannis BSc, MBBS, MRCP, FRCR

Journal of Computer Assisted Tomography: September/October 2010 - Volume 34 - Issue 5 - pp 670-677
doi: 10.1097/RCT.0b013e3181e10627
Cardiovascular Imaging

Purpose: The objectives of this study were (1) to evaluate the potential of low-peak kilovoltage (kVp) images acquired with dual-energy computed tomography (DECT) to improve aortic attenuation and reduce contrast agent utilization and (2) to evaluate the feasibility of material-specific DECT imaging for evaluating aortic disease.

Materials and Methods: Aortic imaging characteristics of 2 groups of patients examined with DECT were compared. In the first group, CT angiography (CTA) was performed in patients with known or suspected aortic disease (CTA group: n = 20, 100-150 mL of contrast at 4.5 mL/s). In the second group, reduced contrast volume CTA was performed in patients with "routine" indications (RC group: n = 20, 50-60 mL at 3 mL/s followed by a saline chaser). In both groups, aortic attenuation and SD were measured at 80 and 140 kVp, and the image quality was analyzed using a 5-point scale. The use of DECT postprocessing techniques for assessing aortic pathology was also evaluated.

Results: For all patients, the aortic attenuation was significantly higher at 80 kVp than at 140 kVp (P < 0.001). Image noise measured quantitatively was higher at 80 kVp (P < 0.001) but did not affect the perceived image quality (P = 0.3). Using low-peak kilovoltage allowed aortic CTA to be performed with a markedly reduced contrast volume and flow rate, with image quality similar to standard CTA (P = 0.2). In a series of cases with proved aortic disease, comparison of true precontrast and subtraction "virtual noncontrast" images showed the potential to eliminate aortic precontrast imaging, reducing radiation exposure.

Conclusions: Single-acquisition DECT combines (1) the benefits of low-kVp vascular imaging (increased iodine conspicuity coupled with a contrast volume/rate reduction) and (2) the use of material-specific imaging techniques to uniquely characterize the aortic pathology.

From the *Division of Thoracic Imaging, Department of Radiology, New York University Langone Medical Center, New York, NY; †Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX; ‡Department of Radiology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil; and §Siemens Medical Solutions, Forchheim, Germany.

Received for publication December 2, 2009; accepted March 8, 2010.

Reprints: Myrna C.B. Godoy, MD, Department of Diagnostic Radiology, The University of Texas MD Anderson Cancer Center, Unit 371, 1515 Holcombe Blvd., Houston, TX 77030 (e-mail: mgodoy@mdanderson.org).

This research was supported by a grant from Bayer HealthCare Pharmaceuticals.

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