# Positron Emission Tomography in Cerebral Amyloid Angiopathy: A Scoping Review
## 3 Results
### Overview  
Amyloid PET imaging has consistently shown an increased global amyloid burden in patients with CAA, and three systematic reviews and a meta-analysis have addressed some general questions. [PERSON] et al. [25] evaluated global amyloid-beta deposition using [11C]PiB PET. They reported significantly elevated global amyloid uptake in symptomatic CAA patients compared to healthy controls and patients with deep intracerebral hemorrhage (ICH). The findings confirmed widespread amyloid deposition in CAA [25]. Similarly, a meta-analysis [26] corroborated these findings, showing that the global amyloid burden is substantially higher in CAA patients than in controls. The effect size for increased global uptake was significant (1.18, 95% CI: 1.08-1.28, \(p<0.0001\)), indicating the utility of amyloid PET in diagnosing CAA and differentiating it from other cerebrovascular conditions. Another relevant issue is regional amyloid deposition, with occipital predominance being more common in CAA than in AD. Occipital predominance of amyloid deposition is a hallmark feature of CAA, and distinguishes it from AD. A study by [PERSON] et al. [26] analyzed the occipital-to-global amyloid uptake ratio, and found that CAA patients exhibited significantly higher ratios than AD patients. This regional preference aligns with the clinical manifestations of CAA, such as occipital lobe hemorrhages and visual disturbances. A related study [9] explored the relationship between regional amyloid burden and symptomatic presentations in CAA, confirming that amyloid deposition is disproportionately higher in posterior regions, particularly the occipital lobes, compared to anterior cortical regions. This occipital predilection helps to differentiate CAA from AD, where amyloid distribution is more diffuse. The occipital-to-global uptake ratio was also validated in the previously cited meta-analysis [26], where CAA patients demonstrated a higher ratio (1.10, 95% CI: 1.03-1.19, \(p=0.009\)) compared to AD patients, further emphasizing the diagnostic value of regional amyloid imaging markers. The main findings of the three published systematic reviews are summarized in Table 2.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Reference** & **Population** & **Details** & **Findings** & **Comments** \\ \hline \multirow{8}{*}{ \begin{tabular}{c} [PERSON] et al., \\ 2017 [25] \\ \end{tabular}  } & \multirow{8}{*}{ \begin{tabular}{c} Probable CAA was diagnosed using \\ Boston criteria [18] and amyloid \\ PREI imaging with [11C]PiB tracer. \\ Possible CAA was diagnosed with \\ Healthy controls \\ (HCs): 30 \\ \end{tabular}  } & \begin{tabular}{c} Probable CAA was diagnosed using \\ Boston criteria [18] and amyloid \\ PET imaging with [11C]PiB tracer. \\ Possible CAA was diagnosed with \\ but unconfirmed CAA, \\ due to lack of definitive imaging \\ or pathology. \\ HCs were matched by age and sex \\ to CAA patients for comparison. \\ \end{tabular}  & \ \begin{tabular}{c} - Significantly higher \\ global [11C]PiB PET \\ uptake in CAA patients \\ compared to controls and \\ deep ICH patients. \\ - Regional amyloid \\ predominance in occipital \\ lobes. \\ - Global amyloid burden \\ higher in CAA vs. controls \\ (effect in: 1.18, 95% CI: \\ - Occipital-to-global \\ uptake ratio significantly \\ in CAA vs. AD \\ (mean ratio: 1.10, 95% CI: \\ - Highening feature between \\ - A and AD, improving \\ - Occipital-to-global \\ - The findings highlight the \\ occipital-to-global ratio as a \\ differentiating feature between \\ CAA and AD, improving \\ - Occipital-to-global \\ - The findings highlight the \\ occipital-to-global ratio as a \\ differentiating feature between \\ CAA and AD, improving \\ - Occipital-to-global \\ - The findings confirm global and \\ regional amyloid deposition \\ patterns as key diagnostic markers. \\ The findings highlight the \\ occipital-to-global ratio as a \\ differentiating feature between \\ CAA and AD, improving \\ \end{tabular}  &
\begin{tabular}{c} The focus was global and regional \\ amyloid deposition in CAA.