The Application Of Different Concentrations Iodine Contrast In CTPA Examination

Objective Compared image quality with 370 mgI/ml and 350 mgI/ml iodine contrast material at various injection velocity, to provide a reference for patients with different conditions to choice the concentration of iodine contrast and the injection velocity when do CTPA.methods The patients which clinical suspected pulmonary embolism who from September 2014 to December 2015 and were do CTPA examination were divided into the 370 mgI/ml or 350 mgI/ml group and then distributed to six velocity subgroups according to the date and order of examination. Two experienced chest radiologists evaluated subjective and objective image quality and record the evaluation results, the objective image quality include: the pulmonary artery trunk CT value, superior vena cava CT value, pulmonary vein CT value, image noise, image signal-to-noise ratio(SNR),contrast to noise ratio(CNR),the subjective quality using a five-grade scale(1 = bad, 2=poor, 3 = moderate, 4 = good, 5 =excellent). Except for gender,parameters with normal distribution were compared between the six various subgroups using analysis of variance and post hoc tests,the same velocity between the two concentration groups using independent sample T test, Non-normal distribution parameters rank and inspection.Results the body mass index in 350 mgI/ml group higher than 370mgI/ml group at4.0ml/s subgroup, the other demographic and morphological date of the patients was no significant between the two concentration groups and six velocity subgroups. With the reduction in flow velocity, the CT attenuation values were reduced in the main pulmonary artery, the other objective image quality evaluation was no significant except the CT attenuation values of pulmonary vein was higher in 370mgI/ml group. Subjective image quality score in the two groups are greater than or equal to 2 points,About the subjective image quality score only one case get 2 score in 370mgI/ml group, all the rest were more than more than 3 score.The main reason of image quality to reduce was the circular function with unstable, then scanning too early or too late and the pulmonary artery contrast filling in 370mgI/ml group, but it was patient's own factors(breathing, movement, or metal artifacts) in 350mgI/ml group. Although the beam hardening of superior vena cava in 370mgI/ml group was significant, they all didn't affect the diagnosis of pulmonary embolism.conclusion subjective and objective of image quality had no significant difference between 370mgI/ml and 350mgI/ml group at the injection velocity from 3.0 ml/s to 4.0 ml/s. Suggest using 350 mgI/ml concentration of iodine contrast to do CTPA, and for the patients whose blood vessels are more brittle should as far as possible choose low velocity.