[¹⁸F]FDG PET may differentiate cerebral amyloid angiopathy from Alzheimer’s disease

Abstract

Background Cerebral amyloid angiopathy (CAA) is a frequent cause of both intracerebral hemorrhage (ICH) and cognitive impairment in the elderly. Diagnosis relies on the Boston criteria, which use magnetic resonance imaging markers including ≥2 exclusively lobar cerebral microbleeds (lCMBs). Although amyloid positron emission tomography (PET) may provide molecular diagnosis, its specificity relative to Alzheimer's disease (AD) is limited due to the prevalence of positive amyloid PET in cognitively normal elderly. Using early‐phase 11C‐Pittsburgh compound B as surrogate for tissue perfusion, a significantly lower occipital/posterior cingulate (O/PC) tracer uptake ratio in probable CAA relative to AD was recently reported, consistent with histopathological lesion distribution. We tested whether this finding could be reproduced using [18F]fluorodeoxyglucose (FDG)‐PET, a widely available modality that correlates well with early‐phase amyloid PET in both healthy subjects and AD. Methods From a large memory clinic database, we retrospectively included 14 patients with probable CAA (Boston criteria) and 21 patients with no lCMB fulfilling AD criteria including cerebrospinal fluid biomarkers. In all, [18F]FDG‐PET/computed tomography (CT) was available as part of routine care. No subject had a clinical history of ICH. Regional standardized [18F]FDG uptake values normalized to the pons (standard uptake value ratio [SUVr]) were obtained, and the O/PC ratio was calculated. Results The SUVr O/PC ratio was significantly lower in CAA versus AD (1.02 ± 0.14 vs. 1.19 ± 0.18, respectively; p = 0.024). Conclusions Despite the small sample, our findings are consistent with the previous early‐phase amyloid PET study. Thus, [18F]FDG‐PET may help differentiate CAA from AD, particularly in cases of amyloid PET positivity. Larger prospective studies, including in CAA‐related ICH, are however warranted.

PET imaging for the evaluation of cerebral amyloid angiopathy: a systematic review

“…Among the 29 studies included in the systematic review, 6 were of retrospective nature [22,28,29,34,39,40] while 23 had a prospective design [17-21, 23-27, 30-33, 35-38, 41-45]. Regarding the device used for scan acquisition, 8 studies used PET only [17][18][19][20][21][22][23][24], 17 studies used PET/CT [25-32, 34-37, 39, 40, 42-45] while 3 studies used PET/ MR [33,38,41].…”

“…Regarding the device used for scan acquisition, 8 studies used PET only [17][18][19][20][21][22][23][24], 17 studies used PET/CT [25-32, 34-37, 39, 40, 42-45] while 3 studies used PET/ MR [33,38,41]. Speaking about radiotracer, 11 C-PIB was used in 13 studies [17-22, 28, 31, 32, 37, 41, 42, 45], 5 studies used 18 F-florbetapir [25,30,33,35,36], 18 F-FDG was used in 3 studies [23,39,40], 18 F-florbetaben ( 18 F-FBB) was used in 2 studies [26,27] and 18 F-flutemetamol was used in one study [38]. Furthermore, some works used more than one tracer and in particular, a study used a combination of 18 F-florbetapir and 11 C-PIB [24], a study was performed with 11 C-PIB and 18 F-FBB [29], a study with 11 C-PIB and 18 F-T807 [43], a study with 11 C-PIB and 18 F-flortaucipir [44] and lastly a study used a combination of three different tracer ( 11 C-PIB, 18 F-FBB and 18 F-flutemetamol) [34].…”

“…Three works investigated the role of 18 F-FDG imaging in CAA [23,39,40], revealing its capability to differentiate between CAA-related and CAA-unrelated CMB [23] and between CAA and AD [40]. Furthermore, the value of 18 F-FBB PET imaging was investigated by two works, demonstrating its ability to differentiate CAArelated inflammation (CAA-ri) from CAA and, with less evidences, from normal controls [26,27].…”

“…More recently two different works by the group Bergeret et al [39,40] investigated the possible role of 18 F-FDG PET imaging to differentiate CAA from AD. Lower occipital/ posterior cingulate SUVR ratio in CAA patients compared to AD subjects was demonstrated.…”

Distinct cerebral cortical perfusion patterns in idiopathic normal‐pressure hydrocephalus

“…Early-phase amyloid positron emission tomography (PET) images are used as a surrogate for brain perfusion (Bergeret et al, 2021).…”