Evan Gary Stein MD, PhD, Abstract Co-Author: Nothing to Disclose

Jose Conrado Rios MD, PhD, Abstract Co-Author: Nothing to Disclose

Mae Mae Andrea Yu-Shih Chu MD, Abstract Co-Author: Nothing to Disclose

Lawrence N. Tanenbaum MD, Abstract Co-Author: Speakers Bureau, General Electric Company Speakers Bureau, Bracco Group Speakers Bureau, Vital Images, Inc Medical Advisory Board, General Electric Company Medical Advisory Board, Bracco Group Medical Advisory Board, Vital Images, Inc

James M. Kessler MD, MPH, Presenter: Nothing to Disclose

Mark Thomas Ellestad MD, Abstract Co-Author: Nothing to Disclose

Puneet Pawha MD, Abstract Co-Author: Nothing to Disclose

Bradley Neil Delman MD, Abstract Co-Author: Medical Advisory Board, Prism Clinical Imaging, Inc

Leveraging the unique atomic densities of different elements, and the ability of modern CT systems to image at multiple energies, dual energy-spectral CT (DESCT) provides novel diagnostic imaging information that can impact on routine CT diagnosis of spine disease. Analysis of the spectral Hounsfield signal behavior of DESCT scans obtained in the presence of spine instrumentation provides the opportunity for selection of the appropriate energy level to minimize artifact and optimize image quality. In this study, we sought to determine the energy level that would maximize the signal-to-noise ratio in the spinal canal of the instrumented spine and to compare these optimal images to those produced from traditional polychromatic 140 kVp and from routine monochromatic 70 keV images.

Ten patients who had previously undergone spinal intervention (5 lumbar, 5 cervical) were imaged on a GE CT750HD using DESCT. The data was processed and spectral Hounsfield unit curves were generated based on a region of interest placed in the spinal canal at the level of the spinal hardware. The optimal keV level for signal-to-noise ratio (SNR) was identified in each case and a set of multiplanar images were generated at that level. These images were compared with a standard 70 keV monochromatic and 140 kVp polychromatic set and evaluated for artifact around the hardware, artifact obscuring the spinal canal, and overall diagnostic quality.

Evaluation of spectral Hounsfield unit curves demonstrates that optimal signal-to-noise ratios were obtained at an energy level between 90 and 95 keV. Comparison of monochromatic images produced at the optimal energy level for each study to the standard monochromatic 70 keV and the 140 kVp polychromatic images demonstrates significant reduction in noise and artifact in the spinal canal. Furthermore, the optimal images for evaluation of the spinal canal were adequate for the assessment of other aspects of the study (e.g. degenerative disease).

The optimal energy level for imaging the instrumented spine ranges from 90-95 keV. Monochromatic images at 93 keV produced images with less artifact in the spinal canal and better hardware visualization, with superior overall quality.

CT of the instrumented spine is challenged by artifact. Optimized monochromatic DESCT produces superior image quality.

Stein, E, Rios, J, Chu, M, Tanenbaum, L, Kessler, J, Ellestad, M, Pawha, P, Delman, B, Dual Energy Spectral CT (DESCT) Allows Selection of the Optimal Monochromatic Energy for Imaging the Instrumented Spine and Improves Diagnostic Quality over Traditional Imaging.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9015776.html