Ultra Low Iodine Loaded Spectral CT Angiography (CTA)

Study Overview
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Brief Summary
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The objectives of this study are: Evaluation of ultra-low iodine load CTA protocols of the aorta and lower extremities. To investigate whether dual-layer in combination with with virtual monoenergetic imaging (VMI) allows for reduction of contrast medium (CM) in CTA of the aorta and lower limbs i with sustained objective and subjective image quality parameters.

Detailed Description
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CT angiography (CTA) of the aorta and the lower limb is one of the most important tools for diagnostic, evaluation of the severity of the peripheral arterial disease, decision making, treatment planning and follow-up; but usually requires the use of iodine contrast medium. Due to the high prevalence of renal impairment (eGFR < 90 ml/min/1.73m) in the elderly hospitalized population (more than 90% among inpatients aged over 60 years) contrast-medium-induced nephropathy is a major concern in this population. The recently introduced spectral CT technique utilizes x-rays covering a spectrum of energy-levels as opposed to conventional CT in which x-rays are set to one specific energy level. This technology offers many possibilities, such as boosting the x-ray contrast effect of iodine. This improves the vascular enhancement of the contrast medium using low-energy, virtual monoenergetic imaging (VNI). The objectives of this study are: Evaluation of ultra-low iodine load CTA protocols of the aorta and lower extremities. To investigate whether dual-layer in combination with with virtual monoenergetic imaging (VMI) allows for reduction of contrast medium (CM) in CTA of the aorta and lower limbs i with sustained objective and subjective image quality parameters.

Official Title
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Ultra Low Iodine Loaded Spectral CT Angiography (CTA) of the Aorta and Lower Limb: A Randomized Controlled Trial

Conditions
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Peripheral Arterial Disease, Renal Insufficiency

Intervention / Treatment
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* Diagnostic Test: Half iodine Spectral CT
* Diagnostic Test: Standard iodine conventional CT


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 standard contrast dose (as calculated with the OmniVis calculator). Patients with clinical suspicion of disease of the aorta and/or arteries in the lower limb. Referral to CTA diagnosis, treatment planning or follow-up. Exclusion Criteria: Iodine contrast medium allergy Age < 18 years Lack of informed consent Critical ischemia of the lower extremities

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: RCT: Patients assigned to study or control group
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Half iodine - Spectral CT group<br>Patients receive half dosage of iodine contrast agent, and Spectral CT acquisition with Virtual Monoenergetic Images at 40 and 50 kiloelectronVolts (keV). | Diagnostic Test: Half iodine Spectral CT<br>* Patients receive half dosage of iodine contrast agent, and Spectral CT acquisition with Virtual Monoenergetic Images at 40 and 50 keV.<br>|
| Active Comparator: Standard iodine - Conventional CT<br>Patients receive standard dosage of iodine contrast agent, and conventional 120 kiloVolts (kV) polychromatic CT images | Diagnostic Test: Standard iodine conventional CT<br>* Patients receive standard dosage of iodine contrast agent, and conventional 120 kv Polychromatic CT acquisition.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mean arterial attenuation | Attenuation (x-ray density) is measured in Hounsfield units (HU) digitally by placing a region of interest (ROI) circle in the Aorta, common iliac-, femoral- and popliteal arteries on the CT images acquired at the time of inclusion. | Measured on CT images acquired at time of inclusion | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective examination quality | Examination quality rated by interventional radiologists on a 4-point scale at the anatomic levels: aorta, common iliac, femoral, popliteal- and calf arteries. Subjective examination quality rating scale: (best) - Excellent: The demarcation of the vessel lumen is excellent, more than sufficient for confident diagnosis or exclusion of stenosis or occlusion. - Good: The demarcation of the vessel lumen is sufficient for confident diagnosis or exclusion of stenosis or occlusion. - Adequate: The demarcation of the vessel lumen is adequate for diagnosis or exclusion of stenosis or occlusion, but with limited confidence. (worst) - Non-diagnostic: There is insufficient demarcation of the vessel lumen for diagnosis or exclusion of stenosis or occlusion. | Rated on CT images acquired at time of inclusion | 
| Rate of diagnostic quality angiography | Based on measurements of attenuation in the aorta, common iliac-, femoral- and popliteal arteries. Diagnostic quality defined as arterial attenuation >200 Hounsfield units (HU) | Measured on images acquired at time of inclusion | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Computed Tomography Angiography, Contrast Media