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GASTROINTESTINAL IMAGING

1031

Dual-Energy (Spectral)
CT: Applications in Abdominal Imaging1
INVITED
COMMENTARY
See discussion on
this article by Blake
(pp 1047–1050).

Alvin C. Silva, MD • BrianG. Morse, MD • Amy K. Hara, MD • Robert
G. Paden, MS • Norio Hongo, MD • William Pavlicek, PhD
Dual-energy imaging is a promising new development in computed
tomography (CT) that has the potential to improve lesion detection
and characterization beyond levels currently achievable with conventional CT techniques. In dual-energy CT (DECT), the simultaneous
use of two different energy settingsallows the differentiation of materials on the basis of their energy-related attenuation characteristics
(material density). The datasets obtained with DECT can be used to
reconstruct virtual unenhanced images as well as iodinated contrast
material–enhanced material density images, obviating the standard
two-phase (unenhanced and contrast-enhanced) scanning protocol
and thus helping minimizethe radiation dose received by the patient.
Single-source DECT, which is performed with rapid alternation between two energy levels, can also generate computed monochromatic
images, which are less vulnerable to artifacts such as beam hardening
and pseudoenhancement and provide a higher contrast-to-noise ratio
than polychromatic images produced by conventional CT. Familiarity with thecapabilities of DECT may help radiologists improve their
diagnostic performance.
©

RSNA, 2011 • radiographics.rsna.org

Abbreviations: DECT = dual-energy CT, dsDECT = dual-source DECT, ssDECT = single-source DECT
RadioGraphics 2011; 31:1031–1046 • Published online 10.1148/rg.314105159 • Content Codes:
From the Department of Radiology, Mayo Clinic, 13400 E Shea Blvd, Scottsdale, AZ 85259 (A.C.S.,A.K.H., R.G.P., W.P.); Department of Radiology, H. Lee Moffitt Cancer Center, Tampa, Fla (B.G.M.); and Department of Radiology, Oita University Faculty of Medicine, Oita, Japan (N.H.).
Recipient of a Certificate of Merit and an Excellence in Design award for an education exhibit at the 2009 RSNA Annual Meeting. Received June 23,
2010; revision requested August 20 and final revision receivedJanuary 7, 2011; accepted January 10. A.C.S. has a research agreement with General
Electric, and A.K.H. is a researcher and has a license agreement with General Electric; all other authors have no financial relationships to disclose.
Address correspondence to A.C.S. (e-mail: silva.alvin@mayo.edu).
1

©

RSNA, 2011

1032 July-August 2011

Introduction

Dual-energy computed tomography(DECT) is a
new application of a fundamental physics concept,
made possible by recent advances in computer
technology and computed tomography (CT) hardware. Although the technique was first reported in
the late 1970s (1–3), it did not achieve widespread
clinical use at that time because of deficiencies
inherent in the immature technology (4). These
deficiencies included (a) motion-relatedmisregistration, a consequence of the acquisition of two
sequential images with long acquisition times (before the advent of spiral CT and multiple detectors); (b) marked image noise related to inefficient
early tube technology, with considerable scatter
radiation at low energy settings; (c) relatively low
spatial resolution; and (d) excessive radiation
exposure.
The development of asingle-detector, singlesource DECT (hereafter, ssDECT) system with
the capability for rapid alternation between
two peak voltage settings (ie, “fast switching”)
(Gemstone Spectral Imaging; GE Healthcare,
Piscataway, NJ) and a dual-detector, dual-source
DECT (hereafter, dsDECT) system (Dual
Source; Siemens Medical Solutions, Erlangen,
Germany) led to renewed interest in clinical use
and further...