We assessed the cerebrovascular status of the included patients with BRAO by grading the initial brain MRI data, which was performed with a 1.5 T or 3.0 T system (Intera or Achieva; Philips Medical Systems, Best, The Netherlands; or Signa Horizon; GE Medical Systems, Milwaukee, WI, USA). The whole brain was scanned with a slice thickness of 5.0 mm in the axial plane using T1-weighted images [repetition time (TR)/echo time (TE) = 300/10], T2-weighted images (TR/TE = 4800/100), fluid-attenuated inversion recovery images (TR/TE = 11,000/140), T2 fast field echo images (TR/TE = 724/23), diffusion-weighted images (TR/TE = 4800/66), and three-dimensional time of flight MRA images (TR/TE = 20/7, slice thickness = 1.2 mm). Acute cerebral infarcts were defined as focal diffusion–restricted lesions in diffusion-weighted images.
9 Cerebral SVD is usually divided into WMHs, CMBs, and silent lacunar infarctions (
Fig. 2).
17 The Fazekas scale was used to assess WMHs. We classified participants into four severity groups according to their Fazekas score: grade 0 (absent), grade 1 (caps or pencil-thin lining), grade 2 (smooth halo), and grade 3 (irregular periventricular signal extending into the deep white matter).
23 White matter hyperintensities were areas of bright, high-signal intensities noted on T2-weighted images. We defined CMBs as black, round lesions with a blooming effect on gradient echo MRI, devoid of T1-weighted or T2-weighted hyperintensity, with at least half of the lesion surrounded by brain parenchyma between 1 and 5 mm in diameter.
24,25 Silent lacunar infarction was defined as focal lesions in the deep perforator territory ≥ 3 mm in diameter with a hyperintense signal on T2-weighted images or fluid attenuation inversion recovery images and a hypointense signal on T1-weighted images, often surrounded by a hyperintense signal rim on fluid attenuation inversion recovery images.
18 Based on this classification, we defined cerebral SVD as one of the following; grade 1 or greater WMHs, presence of CMB, or presence of silent lacunar infarction.