Dual-energy CT Aortography with 50% Reduced Iodine Dose Versus Single-energy CT Aortography with Standard Iodine Dose

William P Shuman; Keith T Chan; Janet M Busey; Lee M Mitsumori; Kent M Koprowicz

doi:10.1016/j.acra.2015.12.019

Dual-energy CT Aortography with 50% Reduced Iodine Dose Versus Single-energy CT Aortography with Standard Iodine Dose

Acad Radiol. 2016 May;23(5):611-8. doi: 10.1016/j.acra.2015.12.019. Epub 2016 Feb 17.

Authors

William P Shuman¹, Keith T Chan², Janet M Busey², Lee M Mitsumori², Kent M Koprowicz²

Affiliations

¹ Department of Radiology, University of Washington School of Medicine, Box 357115, 1959 NE Pacific Street, Seattle, WA 98195. Electronic address: wshuman@uw.edu.
² Department of Radiology, University of Washington School of Medicine, Box 357115, 1959 NE Pacific Street, Seattle, WA 98195.

PMID: 26897602
DOI: 10.1016/j.acra.2015.12.019

Abstract

Rationale and objectives: Because many patients with aortic pathology also have compromised renal function, we wished to investigate dual-energy computed tomography (DECT) aortography with 50% reduced iodine dose compared to single-energy computed tomography (SECT) aortography with standard iodine dose.

Materials and methods: Fifty patients had DECT aortography with 50% reduced iodine dose. Thirty-four of these patients had prior SECT aortography with standard iodine dose. DECT images were reconstructed at both 50 and 77 keV and were compared to SECT 120 kVp images. Reviewers measured aortic attenuation, image noise, and scored vascular enhancement. Signal-to-noise ratios (SNR) and contrast-to-noise ratios (CNR) were calculated. Volume CT dose index was recorded.

Results: Mean iodine dose was 47 g for SECT and 24 g for DECT. Aortic attenuation was highest at reduced iodine dose DECT 50 keV (570 ± 105 Hounsfield units [HU]) compared to 77 keV (239 ± 40 HU) or to standard iodine dose SECT 120 kVp (356 ± 69 HU) (P < 0.05). Image noise was greatest at 50 keV compared to 77 keV and 120 kVp (P < 0.05) but was similar between 77 keV and 120 kVp (P > 0.05). SNR and CNR were the same at 50 keV and 120 kVp (P > 0.05). Mean vascular enhancement scores were all above 3.0 (good, typical enhancement). Volume CT dose index was 11.7 mGy for DECT and 11.8 mGy for SECT (P = 0.37).

Conclusions: DECT aortography with 50% reduced iodine reconstructed at 50 keV resulted in significantly greater aortic attenuation, good subjective vascular enhancement, and comparable SNR and CNR compared to standard iodine dose SECT. DECT image noise at 77 keV was similar to SECT at 120 kVp.

Keywords: Computed tomography; aortography; contrast media; dual energy.

Publication types

Comparative Study

MeSH terms

Aged
Aged, 80 and over
Aorta / diagnostic imaging
Aortography / methods*
Computed Tomography Angiography / methods*
Contrast Media / administration & dosage*
Female
Humans
Image Processing, Computer-Assisted / methods
Iodine / administration & dosage*
Iohexol / administration & dosage
Male
Middle Aged
Prospective Studies
Radiation Dosage*
Radiographic Image Enhancement / methods
Radiography, Dual-Energy Scanned Projection / methods*
Signal-To-Noise Ratio
Triiodobenzoic Acids / administration & dosage

Substances

Contrast Media
Triiodobenzoic Acids
Iohexol
Iodine
iodixanol