Magnetic Resonance Imaging (MRI)

All patients underwent MRI performed with a 1.5 T scanner (SIGNA; GE Medical Systems, Fairfield, CT, USA or Magneton Symphony Advanced or Avanto, Siemens Medical Systems, Erlargen, Germany) or a 3.0 T scanner (SIGNA). The imaging protocol consisted of a T1-weighted spin-echo, a T2-weighted spin-echo, and fluid-attenuated inversion recovery. The severity of WMLs was rated visually from the fluidattenuated inversion-recovery images using the Fazekas scale as follows: no lesions (grade 0), punctate lesions (grade 1), early confluent lesions (grade 2), and confluent lesions (grade 3)¹⁵⁾. Patients were classified into one of two groups according to their Fazekas scale: the mild WML group (0–1) or the severe WML group (2–3). Two stroke neurologists (T.N. and M. A.) who were unaware of the clinical details of the patients graded WML severity for all patients.