Leukoaraiosis (LA) corresponds to an alteration of the encephalic white matter, linked to chronic hypoxia. Its pathophysiology, which has been partially elucidated, is underpinned by chronic changes in the walls of small-caliber perforating arteries, leading to chronic hypoperfusion of the white matter, associated with dysfunction of the blood-brain barrier. In affected areas, this process leads to myelin rarefaction, axonal loss, perivascular alterations and the appearance of cavitation zones. Its existence is mainly linked to the presence of vascular risk factors, most notably arterial hypertension.

MR fingerprinting is an innovative Magnetic resonance Imaging (MRI) technique allowing to obtain a multiparametric MRI sequence in a non-invasively way and in a single acquisition, generating not only multiple contrasts, but also absolute longitudinal relaxation time (T1) and transverse relaxation time (T2) mappings (T1 and T2 mapping). However, the prognostic role of these T2 values, in terms of ischemic, hemorrhagic and cognitive risk, has never been studied. The objective of this study is to study and compare changes in T1 and T2 values of White Matter Hyperintensities (WMH) and Normal Appearing White Matter (NAWM) in subjects with LA.

Inclusion Criteria:

• Patient over 40 years of age
• Suffering from leucoaraiosis
• Diagnosed via cerebral MRI or CT scan performed by the St Philibert Hospital imaging department

For the groups:

• incidental LA (patients included in group 1): on the MRI, FLAIR images showed the presence of hyperintense white matter lesions, assessed at a minimum FAZEKAS grade 2+2, the origin of which was related to small artery disease discovered incidentally or during acute management in GHICL's neurovascular intensive care unit. The CT scan revealed hypodense patches of deep periventricular white matter, also of minimal Fazekas grade 2+2.
• LA and ischemia (patients included in group 2): on the MRI, FLAIR images show the presence of hyperintense white matter lesions with an extent assessed at a minimum grade of FAZEKAS 2+2: their origin is related to small artery disease discovered during acute management of cerebral ischemia in the GHICL's Neurovascular Intensive Care Unit.
• LA and cerebral hemorrhage (patients included in group 3): on the MRI, FLAIR images show the presence of hyperintense white matter lesions of minimal FAZEKAS grade 2+2: their origin is related to small artery disease discovered during the acute management of a cerebral hemorrhage, in the GHICL's Neurovascular Intensive Care Unit.

Exclusion Criteria:

• Claustrophobia preventing MRI scan
• MRI contraindication
• White matter lesions with diagnosis not formally established, doubtful, multifactorial or related to a differential diagnosis
• Patients with dementia or pathology that precludes longitudinal follow-up
• Institutionalized patients
• Agitation not allowing MRI to be performed
• Pregnant women
• Patients under guardianship
• Patients objecting the use of their data

Patient over 40 years of age suffering from leucoaraiosis diagnosed via cerebral MRI or CT scan performed by the St Philibert Hospital (GHICL) imaging department