Strategies to Reduce Contrast Medium in Spectral CT Pulmonary Angiography

Different Strategies to Reduce Contrast Medium in Computed Tomography Pulmonary Angiography Using Spectral Detector CT

The purpose of this study is to assess the effect of three different strategies to inject at reduced volume of contrast medium in Computed Tomography Pulmonary Angiography (CTPA). 330 patients referred for CTPA are randomized to receive either a low-concentration, a low-volume or a saline-diluted injection. Effects on the level and homogeneity of contrast enhancement are measured and compared between groups.

Spectral detector CT facilitates large reductions in contrast medium in vascular CT examinations. To our knowledge, no studies have so far compared different strategies to inject this reduced contrast dose. The purpose of this study is to assess the effect of three different strategies to inject at reduced volume of contrast medium in Computed Tomography Pulmonary Angiography (CTPA). 330 patients referred for clinically indicated CTPA are randomized to receive either a low-concentration, a low-volume or a saline-diluted injection. All patients receive the same amount of iodine (140 mg/kg). Effects on the level and homogeneity of contrast enhancement, image noise, contrast-to-noise-ratio and signal-to-noise-ratio are measured in the CT images and the results are compared between groups.

Patients are randomly assigned to one of three injection methods: low concentration, low-volume and saline-dilution.

Acquired CT images are identical for all participants. The study arm is unknown to all, except the radiographers (radiology technicians) performing the examination.

Patients receive a contrast medium with an iodine concentration of 140 mg/ml. The volume is 1 ml/kg which result in a dose of 140 mg/kg. Maximal dose of contrast medium is 90 ml i.e. 12.6 g of iodine.

Patients receive a contrast medium with an iodine concentration 350 of mg/ml. The volume is 0.4 ml/kg which result in a dose of 140 mg/kg. Maximal dose of contrast medium is 36 ml i.e. 12.6 g of iodine.

Patients receive a contrast medium with an iodine concentration of 350 mg/ml. The contrast medium is diluted 1:1 with saline. The injected volume is 0.8 ml/kg which result in a dose of 140 mg/kg. Maximal dose of contrast medium is 72 ml i.e. 12.6 g of iodine.

Contrast enhancement measured as attenuation in the pulmonary artery Branches on the acquired CTPA examination

Homogeneity of contrast enhancement is measured as the standard deviation of attenuation in the pulmonary artery branches (equals image noise).

Inclusion Criteria: Inpatients and outpatients with kidney function (eGFR) allowing for safe administration of contrast dose (as calculated with the OmniVis calculator). Patients with clinical suspicion of disease of PE Referral to CTPA diagnosis, treatment planning or follow-up. Peripheral venous catheter (PVC) =/< 18 G Exclusion Criteria: Contraindication to iodinated contrast medium Age < 18 years Lack of informed consent Pregnancy