Quantitative assessment and correlation analysis of cerebral microbleed distribution and leukoaraiosis in stroke outpatients

Objective: Cerebral microbleeds (CMBs) are bleeding events associated with cerebral small vessel disease (SVD). Strictly lobar CMBs and strictly deep CMBs are likely caused by cerebral amyloid angiopathy (CAA) and hypertensive arteriopathy, respectively. Leukoaraiosis (LA) reflects an ischaemic change in SVD, and LA severity has been correlated with CMBs. However, whether different locations (aetiologies) of CMBs correlate with LA is unknown. Methods: Patients receiving brain MRI and T2*-weighted gradient-recalled echo scans in a stroke outpatient department were screened for CMBs. The MRI results of the patients with CMBs were sent to investigators for further review and were evaluated using the Microbleed Anatomical Rating Scale. Cerebral microbleed severity was graded using a numerical scale. Leukoaraiosis severity was assessed using the Fazekas scale. Results: Cerebral microbleeds were observed in 14.6% of the 1289 screened patients. The CMB incidence increased with age (in years, <50: 1.3%; 50-59: 10.7%; 60-69: 17.6% and >= 70: 23.6%; P=0.000). The CMB locations were distributed as follows: 23.4% strictly lobar, 12.2% strictly deep, 6.4% strictly infratentorial and 58.0% mixed. Cerebral microbleed severity correlated with the total Fazekas scale score. The numbers of lobar, deep and infratentorial CMBs correlated with the total Fazekas scale score. The mixed CMB group displayed a significantly higher Fazekas scale score than the strictly lobar CMB group (P=0.000). Discussion: Cerebral microbleed incidence increased with age. Mixed CMB type displayed the highest incidence. The severity and number of CMBs at any location correlated with LA severity. These results suggested interactions between hypertension and CAA during LA progression.