How accurate and precise are CT based measurements of iodine concentration? A comparison of the minimum detectable concentration difference among single source and dual source dual energy CT in a phantom study
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To assess the impact of scan- and patient-related factors on the error and the minimum detectable difference in iodine concentration among different generations of single-source (SS) fast kV-switching and dual-source (DS) dual-energy CT (DECT).
Lesions having eight different iodine concentrations (0.2–4 mgI/mL) were emulated in a 3D-printed phantom of medium and large size. Each combination of concentration and size was scanned in dual-energy mode on four different SS and DS DECTs. Radiation doses were 7 and 10 mGy (medium size) and 10, 13, and 16 mGy (large size). Iodine maps were reconstructed with filtered back projection (FBP) and vendor-specific iterative reconstruction algorithms (IRs). Absolute error of iodine quantification (E) was measured. Multivariate regression models determined the influence of CT scanner, iodine concentration, phantom size, radiation dose, and reconstruction algorithm on E. The minimum detectable difference in iodine concentration (ICmin) under the same imaging conditions (intra-conditional) and among different imaging conditions (inter-conditional) was calculated.
The error was significantly lower in current than in previous DECT generations (p < 0.001). For all CT scanner conditions, the error was significantly higher with increasing phantom size and decreasing radiation dose (p < 0.001). Iodine concentration only significantly affected the error for SS DECT (p < 0.001). ICmin depended on patient- and scan-related factors and ranged from 0.4 to 1.5 mgI/mL.
Patient- and scan-related factors have a significant impact on the error and minimum detectable difference in iodine concentration within and among SS fast kV-switching and DS DECT.
• Patient- and scan-related factors have a significant impact on the error and minimum detectable difference in dual-energy CT-based iodine quantification.
• Third-generation DECTs outperformed second-generation scanners for both single-source and dual-source dual-energy CT.
• The minimum intra- and inter-conditional detectable difference in iodine concentration ranged from 0.4 to 1.5 mg iodine/mL.
KeywordsMultidetector computed tomography Iodine Phantom imaging
Dual-energy computed tomography
Dual-energy CT-based iodine quantification
Filtered back projection
Minimum detectable difference in iodine concentration
Iterative reconstruction algorithm
Institutional review board
Renal cell carcinoma
We thank Cristian T. Badea and Yi Qi from the Center of In-Vivo Microscopy of Duke University Medical Center for assistance to create iodinated solutions.
The authors state that this work has not received any funding.
Compliance with ethical standards
The scientific guarantor of this publication is Dr. Andre Euler.
Conflict of interest
The authors of this manuscript declare relationships with the following companies:
Rendon C. Nelson is a medical consultant to GE Healthcare.
Andre Euler is a research fellow supported by GE Healthcare and the Swiss Society of Radiology
Ehsan Samei is the recipient of research funding from Siemens Healthineers and GE Healthcare for projects unrelated to this study.
Statistics and biometry
Maciej A. Mazurowski kindly provided statistical advice for this manuscript.
Approval from the institutional animal care committee was not required because of the design as a phantom study.
Institutional review board approval was not required because of the design as a phantom study.
• performed at one institution
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