Body surface area adapted iopromide 300 mg/ml versus 370 mg/ml contrast medium injection protocol: influence on quantitative and clinical assessment in combined PET/CT.

Purpose: To investigate the quantitative and qualitative differences between combined positron emission tomography and computed X-ray tomography (PET/CT) enhanced with contrast medium with either an iodine concentration 300 mg/ml or 370 mg/ml.

Materials And Methods: 120 consecutive patients scheduled for F-18-Fluorodeoxyglucose (FDG) PET/CT were included. The first (second) 60 patients received contrast medium with 300 (370) mg iodine/ml. Intravenous injection protocols were adapted for an identical iodine delivery rate (1.3mg/s) and body surface area (BSA) adapted iodine dose (22.26 gI/m(2)). Maximum and mean standardized uptake values (SUV(max); SUV(mean)) and contrast enhancement (HU) were determined in the ascending aorta, the abdominal aorta, the inferior vena cava, the portal vein, the liver and the right kidney in the venous contrast medium phase. PET data were evaluated visually for the presence of malignancy and image quality.

Results: Both media caused significantly higher values for HU, SUV(mean) and SUV(max) for the enhanced PET/CT than the non-enhanced one (all p<0.01). There were no significant differences in the degree of increase of HU, SUV(mean) and SUV(max) between the two contrast media at any anatomic site (all p>0.05). Visual evaluation of lesions showed no differences between contrast and non-contrast PET/CT or between the two different contrast media (p=0.77).

Conclusion: When using a constant iodine delivery rate and total iodine dose in a BSA adapted injection protocol, there are no quantitative or qualitative differences in either CT or PET between contrast media with an iodine concentration of 300 mg/ml and 370 mg/ml, respectively.