Program Information
Dual-Energy CT Iodine Accuracy Across Vendors and Platforms
M Jacobsen*, C Wood , D Cody , UT MD Anderson Cancer Center, Houston, TX
Presentations
WE-FG-207B-8 (Wednesday, August 3, 2016) 1:45 PM - 3:45 PM Room: 207B
Purpose: Although a major benefit of dual-energy CT is its quantitative capabilities, it is critical to understand how results vary by scanner manufacturer and/or model before making clinical patient management decisions. Each manufacturer utilizes a specific dual-energy CT approach; cross-calibration may be required for facilities with more than one dual-energy CT scanner type.
Methods: A solid dual-energy quality control phantom (Gammex, Inc.; Appleton, WI) representing a large body cross-section containing three Iodine inserts (2mg/ml, 5mg/ml, 15 mg/ml) was scanned on these CT systems: GE HD-750 (80/140kVp), prototype GE Revolution CT with GSI (80/140kVp), Siemens Flash (80/140kVp and 100/140kVp), and Philips IQon (120kVp and 140kVp). Iodine content was measured in units of concentration (mg/ml) from a single 5mm-thick central image. Three to five acquisitions were performed on each scanner platform in order to compute standard deviation. Scan acquisitions were approximately dose-matched (~25mGy CTDIvol) and image parameters were as consistent as possible (thickness, kernel, no noise reduction applied).
Results: Iodine measurement error ranges were -0.24-0.16 mg/ml for the 2mg/ml insert (-12.0 – 8.0%), -0.28-0.26 mg/ml for the 5mg/ml insert (-5.6 – 5.2%), and -1.16-0.99 mg/ml for the 15mg/ml insert (-7.7 – 6.6%). Standard deviations ranged from 0 to 0.19 mg/ml for the repeated acquisitions from each scanner. The average iodine measurement error and standard deviation across all systems and inserts was -0.21 ± 0.48 mg/ml (-1.5 ± 6.48%). The largest absolute measurement error was found in the 15mg/ml iodine insert.
Conclusion: There was generally good agreement in Iodine quantification across 3 dual-energy CT manufacturers and 4 scanner models. This was unexpected given the widely different underlying dual-energy CT mechanisms employed. Future work will include additional scanner platforms, independent verification of the Iodine insert standard concentrations (especially the 15 mg/ml insert), and how much measurement variability can be clinically tolerated.
Funding Support, Disclosures, and Conflict of Interest: This research has been supported by funds from Dr. William Murphy, Jr., the John S. Dunn, Sr. Distinguished Chair in Diagnostic Imaging at MD Anderson Cancer Center.
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