Strategies to Reduce Contrast Medium in Spectral CT Pulmonary Angiography

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Pulmonary Embolism

Intervention / Treatment
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* Diagnostic Test: Low iodine Spectral Detector CT Pulmonary Angiography


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Interventional Model Description: Patients are randomly assigned to one of three injection methods: low concentration, low-volume and saline-dilution.
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low concentration<br>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. | Diagnostic Test: Low iodine Spectral Detector CT Pulmonary Angiography<br>* Low iodine Spectral Detector CT Pulmonary Angiography<br>|
| Experimental: Low volume<br>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. | Diagnostic Test: Low iodine Spectral Detector CT Pulmonary Angiography<br>* Low iodine Spectral Detector CT Pulmonary Angiography<br>|
| Experimental: Saline Dilution<br>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. | Diagnostic Test: Low iodine Spectral Detector CT Pulmonary Angiography<br>* Low iodine Spectral Detector CT Pulmonary Angiography<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Contrast enhancement (Vascular attenuation) | Contrast enhancement measured as attenuation in the pulmonary artery Branches on the acquired CTPA examination | Measured on the CT images from the examination performed at enrollment | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Homogeneity of contrast enhancement (image noise) | Homogeneity of contrast enhancement is measured as the standard deviation of attenuation in the pulmonary artery branches (equals image noise). | Measured on the CT images from the examination performed at enrollment | 
| Contrast to noise ratio (CNR) | CNR is measured as (Vascular attenuation - Muscular attenuation) / Image noise | Measured on the CT images from the examination performed at enrollment | 
| Signal to noise ratio (SNR) | SNR is measured as Vascular attenuation / Image noise | Measured on the CT images from the examination performed at enrollment | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Pulmonary Embolism, Spectral Detector CT, Contrast medium