Comparison of Spectral Photon Counting CT (SPCCT) With Dual Energy CT (DECT) and Magnetic Resonance Imaging (MRI) for Plaque and Lumen Carotid Arteries Evaluation

Inclusion Criteria:

• Male or female subjects of any ethnic background, aged > 18 years

• Any of the following known or suspected supra-aortic arterial disease based on :Prior stroke; Transient Ischemic Attack; Amaurosis Fugax; Referred for evaluation ofany supra-aortic vessel; Follow-up for a stent in a supra-aortic vessel; Priorimaging ultrasounds study showing > ou = 50 % stenosis of a supra-aortic vesselsegment (within 60 days before consent)

• Patient undergoing surgery within one month of carotid plaque evaluation

• Willingness and ability to follow directions and complete all study proceduresspecified in the protocol

• Pre-menopausal women only : Negative urinary pregnancy test on the day of imagingbefore the administration of study drug

• Patient has accepted to participate to the study and has signed the written consent

• Patient is affiliated to social security

Exclusion Criteria:

• Contraindication to MRI examinations (e.g. inability to hold breath, severearrhythmias, very low cardiac output, severe claustrophobia, metallic devices notapproved for MRI such as defibrillators, pacemaker, heart valve prostheses, cochlearimplants, neuro-stimulators, implanted automated injection device, intraocularmetallic foreign bodies, neurosurgical and vascular clips);

• Contraindication to the use of iodine and gadolinium containing contrast media (including subjects with suspicion for/or known to have NSF);- History of severeallergic or anaphylactic reaction to any allergen including drugs and contrastagents (as judged by the investigator, taking into account the intensity of theevent);

• Estimated Glomerular Filtration Rate (eGFR) value < 30 mL/min/1.73 m2 derived from aserum creatinine result within 1 month before the imaging;

• Any subject on hemodialysis or peritoneal dialysis (Note: If there are multiplecreatinine values, the values obtained prior to and closest to the time of theexamination should be used);

• Acute renal insufficiency of any intensity, either due to hepato-renal syndrome oroccurring in the per-operative liver transplantation period;

• Known subject history of severe cardiovascular disease (e.g. acute myocardialinfarction [< 14 days], unstable angina, congestive heart failure New York HeartAssociation class IV) or known long QT syndrome;

• Suspected clinical instability or unpredictability of the clinical course during thestudy period (e.g. due to previous surgery);

• Scheduled or potentially expected for the period between the SPCCT or DECT and MRI:Any procedure that may alter the MRI or CT interpretation; Any interventional orsurgical procedure involving the supra-aortic vessels.

• Pregnant or nursing (including pumping for storage and feeding); 11. Patient underguardianship, curators or safeguard of justice.