Low-high and high-low biphasic injection forms in computed tomography examinations of the upper abdomen.
OBJECTIVE
To analyze the influence of different biphasic and monophasic injection rate protocols in abdominal computed tomography (CT).


METHODS
A randomized, consecutive, parallel group study was designed and conducted in 60 patients studied with the same CT helical protocol. Patients were randomly distributed into three groups: (A) monophasic (120 ml at 2.5 ml/s); (B) low-high biphasic (120 ml, first 60 ml at a rate of 2 ml/s, the other 60 ml at 2.5 ml/s); and (C) high-low biphasic (120 ml, first 60 ml at a rate of 2.5 ml/s, the other 60 ml at 2 ml/s). All patients were injected with 300 mg I/ml non-ionic contrast media at a fixed delay time of 55 s. Contrast enhancement efficacy was evaluated by attenuation coefficient measurements.


RESULTS
Although non-significant, monophasic protocol enhancements were higher than biphasic protocol enhancements in all measurements except aortic bifurcation (p=0.003). At this level, biphasic protocols obtained an increased mean enhancement from 7.6% to 2.5% compared to monophasic protocols.


CONCLUSIONS
Monophasic contrast agent injection in helical CT of the upper abdomen produces a higher enhancement of parenchymal and venous structures. No significant difference was observed between low-high and high-low biphasic protocols.
Department of Radiology, Clínica Quirón, Valencia, Spain. rmquironv.val@quiron.es
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Martí-Bonmatí
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Arana
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Tobarra
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Sierra
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D003287:Contrast Media / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007275:Injections, Intravenous / Q000379:methods; D008297:Male; D008875:Middle Aged; D011856:Radiographic Image Enhancement / Q000379:methods; D011860:Radiography, Abdominal / Q000379:methods*; D013997:Time Factors; D036542:Tomography, Spiral Computed / Q000379:methods*; D014283:Triiodobenzoic Acids / Q000008:administration & dosage*
D003287:Contrast Media; D014283:Triiodobenzoic Acids; C053571:iopentol