Cerebral Microbleeds Remain for Nine Years: A Prospective Study with Yearly Magnetic Resonance Imaging

Background: Cerebral microbleeds (CMBs) are refined neuroimaging findings detected on T2*-weighted gradient echo (GRE) magnetic resonance imaging (MRI) and are widely accepted as an important marker of the vulnerability of cerebral small vessels. It is necessary to further clarify the natural history of CMBs by a longitudinal study. This study aimed to reveal the natural history of CMBs and find a better way to track CMBs by a prospective long-term observation. Methods: We performed yearly brain MRI assessments for 7 or more years in 8 nonvalvular atrial fibrillation Japanese outpatients with CMBs detected in the baseline MRI. We began to use a 3.0T MRI scanner from 2012 as well. Results: We followed up 3 patients for 9 years, 2 for 8 years, and 3 for 7 years. In all patients, the CMBs at baseline did not disappear during the follow-up period. Importantly, the CMB in 1 patient seemed to disappear during the sixth imaging using 1.5T T2*-weighted GRE but was detected again during the seventh imaging with 3.0T susceptibility weighted imaging and ninth imaging with 3.0T T2*-GRE. Moreover, in a patient implanted with a pacemaker, which is only applicable for 1.5T MRI at present, the CMB seemed to disappear and appeared once again with a 1.5T T2*-weighted GRE at a slice thickness of 2.5 mm instead of 5 mm. Conclusions: From this prospective study, we obtained 2 absolutely new findings that CMBs remained for as long as 9 years and a high-field or thin-slice MRI can detect concealed CMBs.