The MR sequence called MR-ASL is used to measure cerebral perfusion in children. This ASL sequence is used with a unique post-labeling delay (PLD) due to the technical impossibility of setting different post-labeling delays. The use of a single post-labeling, chosen by the pediatric radiology department of the Necker hospital, optimal in children without arteriopathy, may not be suitable for the lengthened arterial transit time of the spins marked in the pathological carotid network of a child with arterial disease.

Recently, ASL sequences with multiple delays (multi-PLD, called eASL) have been developed to overcome this limitation in arterial disease. To date, their use in the pre- and post-treatment evaluation of a child with acute or chronic arterial disease has not been evaluated.

The study hypothesis is that this eASL sequence is more efficient than single-delay ASL in measuring cerebral perfusion. The study will be performed in a population of children with acute or chronic arterial disease.

For 9 years, the pediatric radiology department of the Necker Enfants Malades hospital has routinely used an MR sequence called MR-ASL, which has made it possible to measure cerebral perfusion in children. The service was a pioneer in using this sequence in children and it made it possible to detect areas of cerebral hypo-perfusion (or even pathological hyper-perfusion) and also to monitor post-surgical or spontaneous revascularizations. But this technique suffers from some limitations. Indeed, this ASL sequence is used with a unique post-labeling delay (PLD) of 1025 ms due to the technical impossibility of setting different post-labeling delays. This PLD corresponds to the arterial transit time of the spins marked to have a satisfactory cerebral perfusion. The use of a single post-labeling, chosen short (1025 ms) by the pediatric radiology department of the Necker hospital, optimal in children without arterial disease, may not be suitable for arterial transit time elongated spins marked in the pathological carotid network of a child with arterial disease.

Recently, ASL sequences with multiple delays (multi-PLD, called eASL) have been developed to overcome this limitation in arterial disease. To date, their use in the pre- and post-treatment evaluation of a child with acute or chronic arterial disease has not been evaluated.

The eASL is a sequence that lasts 4 minutes without injection of contrast product that the pediatric radiology department at Necker Hospital intends to add to the standard clinical sequences, as part of this study. This sequence will have no post-labeling delay a priori and will make it possible to test several post-labeling delays in one go. Thus, no a priori hypothesis on the transit time of the spins will be made and the eASL sequence will be able to show, after its reconstruction, what is the optimal post-labeling delay.

The study will be performed in a population of children with acute or chronic arterial disease. The study hypothesis is that this eASL sequence is more efficient than single-delay ASL in measuring cerebral perfusion.

Inclusion Criteria:

• Minor patients aged 0 to 18 with acute or chronic arterial disease: diagnosis of Moya-moya, diagnosis of sickle cell disease, acute and chronic arterial infarction.
• Necessity of diagnostic MR with standard ASL sequences for the care.
• Holders of parental authority and patients informed and not opposed to their participation in the study.

Exclusion Criteria:

• Usual contraindications to MR.
• Movement during ASL / eASL sequences.

Patients with acute or chronic arterial disease followed at Necker hospital.