We evaluated aging of the brain and the status of the vessels in patients with RVO using a 1.5 or 3.0 Tesla MRI scanner (Intera or Achieva; Philips, Best, The Netherlands; Signa; GE, Milwaukee, WI, USA). The 5 mm axial slices were obtained using conventional MR protocols: T1-weighted (repetition time [TR]/echo time [TE], 300/12), T2-weighted (TR/TE, 4800/100), and fluid attenuated inversion recovery (FLAIR) (TR/TE, 11,000/140) images. An additional special protocol, that is T2* gradient-recalled echo (GRE) images (TR/TE, 724/23), was used to assess CMBs, one of the MRI markers for SVD in the brain, and diffusion-weighted MRI (TR/TE, 4800/66) was performed to evaluate acute infarction. The large vessels of the brain were visualized on time-of-flight angiographic images with three-dimensional reconstruction on MRI (TR/TE, 20/7; thickness, 1.2 mm). WMHs, CMBs, silent lacunar infarctions composed of cerebral SVD, and acute cerebral infarcts were defined as focal high-signal lesions on diffusion-weighed MR images.
13,21 WMHs were graded by the Fazekas score (0, absent; 1, caps and thin lining in the ventricle or scattered dot lesions in white matter; 2, smooth halo or early confluent lesions in deep white matter; 3, massive periventricular lesions extending to the deep white matter with a confluent shape).
22 CMBs were defined as round-shaped dark signals with a blooming artifact on T2*-GRE images and within 5 mm in diameter.
23,24 Silent lacunar infarction was detected as a hyperintense signal on T2-weighted or FLAIR images and hypointensity on T2-weighted images with a diameter between 3 mm and 2 cm.
25 As described in our previous study, cerebral SVD was deemed to be present if the brain had one of the following markers: a Fazekas score of 1 or more on WMHs, existence of CMB, or presence of silent lacunar infarction.
26 MR images for the control group were captured using a 1.5 Tesla Chorus MRI scanner (ISOL Technology, Inc., Kyungki-Do, Republic of Korea). No subject in this study had experienced acute ischemic stroke, so routine protocols were used in this survey except for the diffusion-weighted images. T1-weighted (TR/TE = 520/12), T2-weighted (TR/TE = 5800/96), FLAIR (TR/TE = 8500/96; inversion time = 2100), and T2*-GRE (TR/TE = 150/15; flip angle, 26°) images were obtained. One set of images comprised 24 transaxial slices per scan without an interslice gap.