Effects of contrast medium injection technique on attenuation values of adrenal glands in healthy dogs during contrast-enhanced computed tomography

Alexandra Blaser Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Matthias Dennler Section of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Martina Mosing Anaesthesiology Section, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Thomas C. Gent Anaesthesiology Section, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Guido Santner Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Section of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Anaesthesiology Section, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Anaesthesiology Section, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Institute of Pharmacology and Toxicology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Section of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.
Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Sandro Imhasly Institute of Pharmacology and Toxicology, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Felicitas S. Boretti Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Claudia E. Reusch Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Patrick Kircher Section of Diagnostic Imaging, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Nadja S. Sieber-Ruckstuhl Clinic for Small Animal Internal Medicine, Vetsuisse Faculty, University of Zurich, Winterthurerstrasse 260, 8057 Zurich, Switzerland.

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Abstract

OBJECTIVE To assess the effects of 3 contrast medium injection techniques on attenuation values for canine adrenal glands during contrast-enhanced CT.

ANIMALS 9 healthy Beagles.

PROCEDURES 3 protocols were evaluated in a randomized cross-over design study: 700 mg of iodine/kg at a constant injection rate over 20 seconds (full-dose constant rate), the same dose at a rate following an exponential decay curve over 20 seconds (full-dose decelerated rate), and 350 mg of iodine/kg at a constant injection rate over 10 seconds (half-dose constant rate). Multislice CT images were obtained before and at predetermined time points after the start of contrast medium injection.

RESULTS Median peak attenuation values were 129, 133, and 87 Hounsfield units with the full-dose constant rate, full-dose decelerated rate, and half-dose constant rate injection protocols, respectively. Peak attenuation differed significantly between the full-dose constant rate and half-dose constant rate injection protocols and between the full-dose decelerated rate and half-dose constant rate injection protocols. Median time to peak attenuation did not differ significantly among injection methods and was 30, 23, and 15 seconds for the full-dose constant rate, full-dose decelerated rate, and half-dose constant rate injections, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE The dose of contrast medium and the timing of postinjection CT scanning were main determinants of peak attenuation for adrenal glands in healthy dogs; effects of the 3 injection protocols on attenuation were minor. The exponentially decelerated injection method was subjectively complex. A constant injection protocol delivering 700 mg of iodine/kg over 20 seconds, with scans obtained approximately 30 seconds after starting contrast medium injection, provided images with maximum adrenal gland attenuation values. (Am J Vet Res 2016;77:144–150)

Abstract

OBJECTIVE To assess the effects of 3 contrast medium injection techniques on attenuation values for canine adrenal glands during contrast-enhanced CT.

ANIMALS 9 healthy Beagles.

PROCEDURES 3 protocols were evaluated in a randomized cross-over design study: 700 mg of iodine/kg at a constant injection rate over 20 seconds (full-dose constant rate), the same dose at a rate following an exponential decay curve over 20 seconds (full-dose decelerated rate), and 350 mg of iodine/kg at a constant injection rate over 10 seconds (half-dose constant rate). Multislice CT images were obtained before and at predetermined time points after the start of contrast medium injection.

RESULTS Median peak attenuation values were 129, 133, and 87 Hounsfield units with the full-dose constant rate, full-dose decelerated rate, and half-dose constant rate injection protocols, respectively. Peak attenuation differed significantly between the full-dose constant rate and half-dose constant rate injection protocols and between the full-dose decelerated rate and half-dose constant rate injection protocols. Median time to peak attenuation did not differ significantly among injection methods and was 30, 23, and 15 seconds for the full-dose constant rate, full-dose decelerated rate, and half-dose constant rate injections, respectively.

CONCLUSIONS AND CLINICAL RELEVANCE The dose of contrast medium and the timing of postinjection CT scanning were main determinants of peak attenuation for adrenal glands in healthy dogs; effects of the 3 injection protocols on attenuation were minor. The exponentially decelerated injection method was subjectively complex. A constant injection protocol delivering 700 mg of iodine/kg over 20 seconds, with scans obtained approximately 30 seconds after starting contrast medium injection, provided images with maximum adrenal gland attenuation values. (Am J Vet Res 2016;77:144–150)

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