Cerebral MBs and SS are frequent neuroimaging findings in patients with LPA, often with frontal lobe predilection. CAA is hypothesized to be the major pathologic determinant of MB/SS in these patients; however, neuroimaging-pathologic data are limited.

We conducted an imaging-pathology study on patients  prospectively recruited by the Neurodegenerative Research Group (NRG) at Mayo Clinic (Rochester, MN) between 2010 and 2015 that met the following inclusion criteria: 1) received an ante mortem LPA diagnosis; 2) had a gradient-recalled echo (GRE) T2-weighted magnetic resonance imaging (MRI) performed; 3) had Pittsburgh compound B (PiB) PET scan performed 3) died and completed a brain autopsy. Demographic, genetic, neuroimaging, clinical and pathologic characteristics were compared between patients with and without MB/SS. Two-tailed Fisher’s Exact and Wilcoxon rank sum tests were used for comparison of categorical and continuous variables, respectively.

Thirteen patients met inclusion criteria, six (46%) had MB/SS on GRE T2-weighted MRI. Moderate/severe CAA was associated with the presence of MB/SS, p=0.029. No other demographic, genetic, imaging or pathologic associations were found. As expected, MB/SS most frequently involved the frontal lobes, followed by the parietal lobes. No clear associations were found between regional MB/SS distribution and regional distribution of CAA. There was some evidence for a regional association between MB/SS and uptake of PiB although not in all patients.

The presence of MB/SS is a strong indicator of underlying moderate/severe CAA in LPA, although the biological mechanisms underlying the topographic distribution of MB/SS remain unclear.