Chiang, Meng-TingMeng-TingChiangCHIA-JU LIUBO-CHING LEERUOH-FANG YENHSIN-HSI TSAI2025-05-052025-05-052025-05https://scholars.lib.ntu.edu.tw/handle/123456789/728822Background: Cerebral amyloid angiopathy (CAA) is a major cause of lobar intracerebral hemorrhage and cognitive dysfunction in the elderly, and frequently coexists with Alzheimer's disease and tau pathology. Dual-phase 11C-PiB PET detects amyloid deposition and cerebral perfusion changes and may have diagnostic value for identifying tau in CAA. Methods: We prospectively enrolled patients with probable CAA for dynamic PiB and AV1451 scans. We compared early-phase (0–6 min after tracer injection) and late-phase (40–70 min) PiB PET between the tau(+) and tau(−) groups (based on AV1451 PET) and investigated their diagnostic values for detecting tau. Results: CAA/tau(+) had lower early-phase temporal PiB uptake than CAA/tau(−) (p = 0.014) and higher late-phase uptake in the whole cortex and temporal and parietal lobes (all p < 0.05). Early-phase temporal PiB SUVR correlated with tau burden (r = −0.34, p = 0.038). Using Youden's cut-off, early-phase and late-phase PET had sensitivities of 55% and 80% and specificities of 85% and 65% for detecting tau, respectively. Combining early- and late-phase scans provided a rule-out sensitivity of 90% and rule-in specificity of 100% for tau pathology in CAA. Conclusions: Dual-phase 11C-PiB PET represents a reliable approach for assessing tau and could potentially identify CAA patients for tau biomarker testing.entrueC‐11 Pittsburgh compound‐B positron emission tomography (C‐11 PiB PET)cerebral amyloid angiopathy (CAA)early‐phase amyloid PETneurodegenerationtau PET[SDGs]SDG3journal article10.1002/acn3.70021400335792-s2.0-86000194635