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Published in: European Radiology 12/2018

Open Access 01-12-2018 | Computed Tomography

Comparing dual energy CT and subtraction CT on a phantom: which one provides the best contrast in iodine maps for sub-centimetre details?

Authors: Evelinda Baerends, Luuk J. Oostveen, Casper T. Smit, Marco Das, Ioannis Sechopoulos, Monique Brink, Frank de Lange, Mathias Prokop

Published in: European Radiology | Issue 12/2018

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Abstract

Objectives

To compare contrast-to-noise ratios (CNRs) and iodine discrimination thresholds on iodine maps derived from dual energy CT (DECT) and subtraction CT (SCT).

Methods

A contrast-detail phantom experiment was performed with 2 to 15 mm diameter tubes containing water or iodinated contrast concentrations ranging from 0.5 mg/mL to 20 mg/mL. DECT scans were acquired at 100 kVp and at 140 kVp+Sn filtration. SCT scans were acquired at 100 kVp. Iodine maps were created by material decomposition (DECT) or by subtraction of water scans from iodine scans (SCT). Matched exposure levels varied from 8 to 15 mGy. Iodine discrimination thresholds (Cr) and response times were determined by eight observers.

Results

The adjusted mean CNR was 1.9 times higher for SCT than for DECT. Exposure level had no effect on CNR. All observers discriminated all details ≥10 mm at 12 and 15 mGy. For sub-centimetre details, the lowest calculated Cr was ≤ 0.50 mg/mL for SCT and 0.64 mg/mL for DECT. The smallest detail was discriminated at ≥4.4 mg/mL with SCT and at ≥7.4 mg/mL with DECT. Response times were lower for SCT than DECT.

Conclusions

SCT results in higher CNR and reduced iodine discrimination thresholds compared to DECT for sub-centimetre details.

Key Points

• Subtraction CT iodine maps exhibit higher CNR than dual-energy iodine maps
• Lower iodine concentrations can be discriminated for sub-cm details with SCT
• Response times are lower using SCT compared to dual-energy CT
Appendix
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Metadata
Title
Comparing dual energy CT and subtraction CT on a phantom: which one provides the best contrast in iodine maps for sub-centimetre details?
Authors
Evelinda Baerends
Luuk J. Oostveen
Casper T. Smit
Marco Das
Ioannis Sechopoulos
Monique Brink
Frank de Lange
Mathias Prokop
Publication date
01-12-2018
Publisher
Springer Berlin Heidelberg
Published in
European Radiology / Issue 12/2018
Print ISSN: 0938-7994
Electronic ISSN: 1432-1084
DOI
https://doi.org/10.1007/s00330-018-5496-x

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