Non-Inferiority of Reduced-Rate Iodixanol Injection Protocols for Diagnostic Cerebral Angiography in Patients with Unruptured Intracranial Aneurysms

The primary objective is to demonstrate the non-inferiority of reduced-rate and reduced-volume iodinated contrast media injection protocols, administered selectively through internal carotid and vertebral artery catheterisation, compared with the standard protocol used in cerebral angiography. The clinical relevance is the preservation of diagnostic image quality for the evaluation of intracranial aneurysms while using lower contrast administration parameters.

The secondary objectives are to evaluate reproducibility of the classification of images as exploitable or non-exploitable between radiographers and interventional neuroradiologists; to assess patient discomfort and satisfaction across the different injection protocols; to examine the metrological properties of an innovative quality assessment grid versus traditional subjective image analysis; to analyse the economic and environmental impact of the protocols; and to evaluate their effect on examination duration and the need for image repetition.

The sponsor did not provide the total number of participants. The trial population included adult patients with intracranial aneurysms, both female and male, aged 18 to 80 years, who were generally conscious, oriented, and able to undergo diagnostic cerebral angiography under simple local anaesthesia as part of routine care. Participants were selected from individuals scheduled for initial assessment of a suspected or detected aneurysm on non-invasive imaging, or for follow-up of one or more treated or untreated aneurysms. Relevant selection requirements included the ability to understand the study information and provide signed informed consent, the ability to answer oral or written questions in French or to understand French, a negative serum β-HCG test for women of childbearing potential, and coverage by a social security health insurance plan. No information was provided on lifestyle considerations such as diet, physical activity, or habits.

This randomized and controlled clinical trial evaluates reduced-flow and reduced-volume iodinated contrast media injection protocols versus the standard protocol used in diagnostic cerebral angiography for the assessment of unruptured intracranial aneurysms. The main objective is to determine non-inferiority with respect to image quality. The overall trial duration is planned from May 2026 to May 2029. Study participation begins with an inclusion screening visit, during which eligibility is verified, informed consent is obtained, and the required baseline assessments are performed, including serum β-HCG testing for women of childbearing potential. Participants then undergo the scheduled angiography procedure according to the assigned protocol, with assessments performed during the examination and after each injection or acquisition as applicable. Follow-up assessments are completed at the end of the examination, including evaluation of discomfort, satisfaction, side effects, and image exploitability, and the end-of-study visit corresponds to completion of these final assessments. Expected participant involvement is limited to the period required for screening, the angiography procedure, and same-day study assessments. Early termination may occur if eligibility criteria are not met, if informed consent is not provided or withdrawn, if the participant is unable to undergo the procedure under simple local anaesthesia, or if the participant cannot complete the required study procedures.

Iodixanol was administered as a solution for injection for intraarterial use. The investigational product was Visipaque 270 550 mg/ml (270 mg I/ml), supplied at a dose of 25 mL. It was selectively administered via internal carotid and vertebral artery catheterisation as part of reduced-rate and reduced-volume iodinated contrast media injection protocols in diagnostic cerebral angiography.

The study compared these reduced-rate and reduced-volume injection protocols with the standard protocol used in the trial setting. Administration was performed according to the assigned injection protocol, with dosing and flow parameters defined by the study design. Participant compliance was monitored through adherence to the specified injection protocol during cerebral angiography.

Efficacy will be assessed by the ratio of exploitable 2D and 3D images obtained with each injection protocol and compared with the standard protocol. Images will be evaluated by radiographers. The assessment will cover reduced flow rates and standard volumes, reduced volumes and standard flow rates, and reduced flow rates and volumes. The primary comparison will be based on image quality for the evaluation of unruptured intracranial aneurysms in cerebral angiography.

Secondary efficacy assessments will include agreement between radiographers’ evaluation and interventional neuroradiologist evaluation for images classified as exploitable or non-exploitable, as well as inter-evaluator reproducibility between radiographers, between neuroradiologists, and between radiographers and neuroradiologists. A qualitative assessment grid will also be analyzed for its results, correlation with quantitative findings, predictive reliability for image exploitability, and inter-evaluator reproducibility.