Diagnostic utility of integrated ¹¹C-Pittsburgh compound-B positron emission tomography/magnetic resonance imaging for cerebral amyloid angiopathy: a pilot study

Objectives: We aimed to compare amyloid deposition at the lobar cerebral microbleed (CMB) sites of cerebral amyloid angiopathy (CAA), Alzheimer’s disease (AD) and cognitively normal healthy controls (NC), and to assess the diagnostic value of integrated ¹¹C-Pittsburgh compound-B positron emission tomography (PET)/magnetic resonance (MR) for CAA against AD.

Methods: 10 CAA, 15 AD, and 15 NC subjects were enrolled in this retrospective study. Each subject underwent a ¹¹C-PIB PET/MR examination. Susceptibility weighted imaging was assessed to detect CMB locations, and standardized uptake value ratios (SUVRs) were measured at these sites. CAA, AD, and NC subjects were compared for global and regional PIB retention. The diagnostic accuracy of MRI, PIB-PET, and PET/MR in differentiating CAA and AD were evaluated.

Results: The PIB deposition at CMB sites was significantly higher in CAA than in AD and NC subjects (p<0.0001). The global cortical PIB deposition was significantly higher in CAA than in NC subjects (p<0.0001) and significantly lower than in AD patients (p<0.0001). In contrast, the occipital/global ratio was significantly higher in CAA than AD patients (p <0.001). PET/MR had a higher accuracy (sensitivity, 88.9%; specificity, 93.3%) than separate PET and MR.

Conclusions: Our results indicate that the CMBs occur preferentially at loci with concentrated amyloid. Combining lobar CMBs with regional cortical amyloid deposition can further improve CAA diagnostic accuracy. These findings improve our knowledge regarding the pathogenesis of CMBs and highlight the potential utility of PIB-PET/MR as a non-invasive tool for distinguishing CAA and AD patients.