Amyloid Imaging of Dutch-type Hereditary Cerebral Amyloid Angiopathy Carriers.

Objective To determine whether amyloid imaging with the positron emission tomography (PET) agent Pittsburgh compound B (PiB) can detect vascular beta-amyloid (A beta) in the essentially pure form of cerebral amyloid angiopathy associated with the Dutch-type hereditary cerebral amyloid angiopathy (D-CAA) mutation. Methods PiB retention in a cortical composite of frontal, lateral, and retrosplenial regions (FLR) was measured by PiB-PET in 19 D-CAA mutation carriers (M+; 13 without neurologic symptoms, 6 with prior lobar intracerebral hemorrhage) and 17 mutation noncarriers (M-). Progression of PiB retention was analyzed in a subset of 18 serially imaged individuals (10 asymptomatic M+, 8 M-). We also analyzed associations between PiB retention and cerebrospinal fluid (CSF) A beta concentrations in 17 M+ and 11 M- participants who underwent lumbar puncture and compared the findings to PiB-PET and CSF A beta in 37 autosomal dominant Alzheimer disease (ADAD) mutation carriers. Results D-CAA M+ showed greater age-dependent FLR PiB retention (p < 0.001) than M-, and serially imaged asymptomatic M+ demonstrated greater longitudinal increases (p = 0.004). Among M+, greater FLR PiB retention associated with reduced CSF concentrations of A beta 40 (r = -0.55, p = 0.021) but not A beta 42 (r = 0.01, p = 0.991). Despite comparably low CSF A beta 40 and A beta 42, PiB retention was substantially less in D-CAA than ADAD (p < 0.001). Interpretation Increased PiB retention in D-CAA and correlation with reduced CSF A beta 40 suggest this compound labels vascular amyloid, although to a lesser degree than amyloid deposits in ADAD. Progression in PiB signal over time suggests amyloid PET as a potential biomarker in trials of candidate agents for this untreatable cause of hemorrhagic stroke. ANN NEUROL 2019