Background and purpose: Silent brain infarcts (SBIs) have been recognized as common lesions in elderly subjects and their diagnosis relies on brain imaging. In this study, we aimed to evaluate the different MRI parameters and criteria used for their evaluation in the literature to better understand the variation across studies and related limitations.
Method: Original MRI studies of SBI performed in human populations and reported in the English literature were reviewed. Analyses were restricted to population-based studies or studies in which at least 50 subjects with SBI were detected. The MRI parameters as well as the MRI criteria of SBI (size, signal characteristics, and criteria for differentiation of dilated Virchow-Robin spaces) were described and analyzed.
Result: Magnetic field strength, slice thickness, and gap between slices greatly varied among the 45 articles included in this review. The MRI definition of SBI was inconsistent across studies. In half of them, SBI was defined as hypointense on T1 and hyperintense on T2-weighted images. Exclusion criteria for dilated Virchow-Robin spaces were used only in 7 studies.
Conclusions: The variation in MRI characteristics and diagnostic criteria for SBI represent a major limitation for interpretation and comparison of data between studies. Efforts are needed to reach unified imaging criteria for SBI.