Title: Contrast enhanced abdominal computerised tomography using a reduced volume of high concentration iodinated contrast medium to achieve a dose reduction.

Abstract

Aim:  We aim to evaluate whether a reduced volume of high concentration iodinated contrast material could be used in abdominal CT to achieve an iodine load reduction without adversely affecting image quality.

Materials and methods:  150 portal venous phase abdominal CT investigations were reviewed retrospectively and the degree of visceral opacification measured using the liver as representative.   Two groups of patients were studied whom received either either 100 ml of Optiray 300 mg/ml or 75 ml of Optiray 350 mg/ml intravenous contrast material prior to the CT.

Results:  The iodine dose was lower in the 75 ml Optiray 350 group (26.25 g group) than the 100 ml Optiray 300 group (30 g group).  Mean CT density of liver parenchyma was statistically significantly lower in the 26.25 g group 80 HU 95 % CI (78.2, 82.0) vs the 30 g group 86.6 HU 95 % CI (83.7, 89.6). Both protocols achieved diagnostically acceptable images with liver opacification above 50 HU in at least 95%.  The 30 g group achieved liver opacification above 50 HU in 95 % of cases, the 26.25 g group achieved liver opacification above 50 HU in 98.5%.

Conclusion:  A modest reduction in the dose of administered intravenous contrast may be achieved  by mildly reducing the mean visceral opacification but without adversely affecting the diagnostic value of the images obtained.