Impact of low-energy CT imaging on selection of positive oral contrast media concentration
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To determine to what extent low-energy CT imaging affects attenuation of gastrointestinal tract (GIT) opacified with positive oral contrast media (OCM). Second, to establish optimal OCM concentrations for low-energy diagnostic CT exams.
One hundred patients (38 men and 62 women; age 62 ± 11 years; BMI 26 ± 5) with positive OCM-enhanced 120-kVp single-energy CT (SECT), and follow-up 100-kVp acquisitions (group A; n = 50), or 40–70-keV reconstructions from rapid kV switching-single-source dual-energy CT (ssDECT) (group B; n = 50) were included. Luminal attenuation from different GIT segments was compared between exams. Standard dose of three OCM and diluted solutions (75%, 50%, and 25% concentrations) were introduced serially in a gastrointestinal phantom and scanned using SECT (120, 100, and 80 kVp) and DECT (80/140 kVp) acquisitions on a ssDECT scanner. Luminal attenuation was obtained on SECT and DECT images (40–70 keV), and compared to 120-kVp scans with standard OCM concentrations.
Luminal attenuation was higher on 100-kVp (328 HU) and on 40–60-keV images (410–924 HU) in comparison to 120-kVp scans (298 HU) in groups A and B (p < 0.05). Phantom: There was an inverse correlation between luminal attenuation and X-ray energy, increasing up to 527 HU on low-kVp and 999 HU on low-keV images (p < 0.05). 25% and 50% diluted OCM solutions provided similar or higher attenuation than 120 kVp, at low kVp and keV, respectively.
Low-energy CT imaging increases the attenuation of GIT opacified with positive OCM, permitting reduction of 25%–75% OCM concentration.
KeywordsComputed tomography Oral contrast media Dual energy CT Gastrointestinal tract
The authors are extremely grateful and sincerely acknowledge the involvement of Jerry Jones, Luis Colon, Vyoma Sahani, Srishti Lulla, Olivia Long, and Maxeem Abedi-Tari during the CT scanning of the anthropomorphic phantom and data analysis. We also acknowledge Dr. Rodrigo Canellas M.D for his collaboration with the statistical analysis.
Compliance with ethical standards
No funding was received for this study.
Conflict of interest
Dushyant V. Sahani has received research grants from General Electric Healthcare. The other authors declare that they have no conflict of interest.
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. This article does not contain any studies with animals performed by any of the authors. Institutional Review Board approval was obtained for this study.
Statement of informed consent was not applicable since the manuscript does not contain any patient data.
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