A comparison of cerebral amyloid angiopathy in the cerebellum and CAA-positive occipital lobe of 60 brains from routine autopsies

New objective simple evaluation methods of amyloid PET/CT using whole-brain histogram and Top20%-Map

OBJECTIVE

This study aims to assess the utility of newly developed objective methods for the evaluation of intracranial abnormal amyloid deposition using PET/CT histogram without use of cortical ROI analyses.

METHODS

Twenty-five healthy volunteers (HV) and 38 patients with diagnosed or suspected dementia who had undergone 18F-FPYBF-2 PET/CT were retrospectively included in this study. Out of them, 11C-PiB PET/CT had been also performed in 13 subjects. In addition to the conventional methods, namely visual judgment and quantitative analyses using composed standardized uptake value ratio (comSUVR), the PET images were also evaluated by the following new parameters: the skewness and the mode-to-mean ratio (MMR) obtained from the histogram of the brain parenchyma; Top20%-map highlights the areas with high tracer accumulation occupying 20% volume of the total brain parenchymal on the individual's CT images. We evaluated the utility of the new methods using histogram compared with the visual assessment and comSUVR. The results of these new methods between 18F-FPYBF-2 and 11C-PiB were also compared in 13 subjects.

RESULTS

In visual analysis, 32, 9, and 22 subjects showed negative, border, and positive results, and composed SUVR in each group were 1.11 ± 0.06, 1.20 ± 0.13, and 1.48 ± 0.18 (p < 0.0001), respectively. Visually positive subjects showed significantly low skewness and high MMR (p < 0.0001), and the Top20%-Map showed the presence or absence of abnormal deposits clearly. In comparison between the two tracers, visual evaluation was all consistent, and the ComSUVR, the skewness, the MMR showed significant good correlation. The Top20%-Maps showed similar pattern.

CONCLUSIONS

Our new methods using the histogram of the brain parenchymal accumulation are simple and suitable for clinical practice of amyloid PET, and Top20%-Map on the individual's brain CT can be of great help for the visual assessment.

Superficial small cerebellar infarcts in cerebral amyloid angiopathy on 3 T MRI: A preliminary study

BACKGROUND

Strictly superficial cerebellar microbleeds and cerebellar superficial siderosis have been considered markers of advanced cerebral amyloid angiopathy (CAA), but there are few studies on cerebellar ischemic lesions in CAA. We investigated the presence of superficial small cerebellar infarct (SCI) ≤15 mm and its relation to magnetic resonance imaging (MRI) markers in patients with probable CAA.

METHODS

Eighty patients with probable CAA were retrospectively evaluated. The presence of superficial SCIs was examined, along with cerebellar microbleeds and cerebellar superficial siderosis, using 3-T MRI. Lobar cerebral microbleeds, cortical superficial siderosis (cSS), enlargement of the perivascular space in the centrum semiovale, and white matter hyperintensity were assessed and the total CAA-small vessel disease (SVD) score was calculated.

RESULTS

Nine of the 80 patients (11.3%) had a total of 16 superficial SCIs. By tentatively defining SCI <4 mm as cerebellar microinfarcts, 8 out of 16 (50%) superficial SCIs corresponded to cerebellar microinfarcts. The total CAA-SVD score was significantly higher in patients with superficial SCIs (p = 0.01). The prevalence of cSS (p = 0.018), cortical cerebral microinfarct (p = 0.034), and superficial cerebellar microbleeds (p = 0.006) was significantly higher in patients with superficial SCIs. The number of superficial cerebellar microbleeds was also significantly higher in patients with superficial SCIs (p = 0.001).

CONCLUSIONS

Our results suggest that in patients with CAA, superficial SCIs (including microinfarcts) on MRI may indicate more severe, advanced-stage CAA. These preliminary findings should be verified by larger prospective studies in the future.

Inhibitor of DNA Binding Protein 3 (ID3) and Nuclear Respiratory Factor 1 (NRF1) Mediated Transcriptional Gene Signatures are Associated with the Severity of Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is a degenerative vasculopathy. We have previously shown that transcription regulating proteins- inhibitor of DNA binding protein 3 (ID3) and the nuclear respiratory factor 1 (NRF1) contribute to vascular dysregulation. In this study, we have identified sex specific ID3 and NRF1-mediated gene networks in CAA patients diagnosed with Alzheimer's Disease (AD). High expression of ID3 mRNA coupled with low NRF1 mRNA levels was observed in the temporal cortex of men and women CAA patients. Low NRF1 mRNA expression in the temporal cortex was found in men with severe CAA. High ID3 expression was found in women with the genetic risk factor APOE4. Low NRF1 expression was also associated with APOE4 in women with CAA. Genome wide transcriptional activity of both ID3 and NRF1 paralleled their mRNA expression levels. Sex specific differences in transcriptional gene signatures of both ID3 and NRF1 were observed. These findings were further corroborated by Bayesian machine learning and the GeNIe simulation models. Dynamic machine learning using a Monte Carlo Markov Chain (MCMC) gene ordering approach revealed that ID3 was associated with disease severity in women. NRF1 was associated with CAA and severity of this disease in men. These findings suggest that aberrant ID3 and NRF1 activity presumably plays a major role in the pathogenesis and severity of CAA. Further analyses of ID3- and NRF1-regulated molecular drivers of CAA may provide new targets for personalized medicine and/or prevention strategies against CAA.

Characterization of cerebellar amyloid-β deposits in Alzheimer disease

Cerebellar amyloid-β (Aβ) plaques are a component of the diagnostic criteria used in Thal staging and ABC scoring for Alzheimer disease (AD) neuropathologic change. However, Aβ deposits in this anatomic compartment are unique and under-characterized; and their relationship with other pathological findings are largely undefined. In 73 cases of pure or mixed AD with an A3 score in the ABC criteria, parenchymal (plaques) and vascular (cerebral amyloid angiopathy [CAA]) cerebellar Aβ-42 deposits were characterized with respect to localization, morphology, density, and intensity. Over 85% of cases demonstrated cerebellar Aβ-42 parenchymal staining that correlated with a Braak stage V-VI/B3 score (p < 0.01). Among the 63 with cerebellar Aβ-42 deposits, a diffuse morphology was observed in 75% of cases, compact without a central dense core in 32%, and compact with a central dense core in 16% (all corresponding to plaques evident on hematoxylin and eosin staining). Cases with Purkinje cell (PC) loss showed higher proportions of PC layer Aβ-42 staining than cases without PC loss (88% vs 44%, p = 0.02), suggesting a link between Aβ-42 deposition and PC damage. Among all 73 cases, CAA was observed in the parenchymal vessels of 19% of cases and in leptomeningeal vessels in 44% of cases.

Comparative examination of the pons and corpus callosum as reference regions for quantitative evaluation in positron emission tomography imaging for Alzheimer's disease using 11C-Pittsburgh Compound-B

OBJECTIVES

Standardised uptake value ratio (SUVR) is usually obtained by dividing the SUV of the region of interest (ROI) by that of the cerebellar cortex. Cerebellar cortex is not a valid reference in cases where amyloid β deposition or lesions are present. Only few studies have evaluated the use of other regions as references. We compared the validity of the pons and corpus callosum as reference regions for the quantitative evaluation of brain positron emission tomography (PET) using ¹¹C-PiB compared to the cerebellar cortex.

METHODS

We retrospectively evaluated data from 86 subjects with or without Alzheimer's disease (AD). All subjects underwent magnetic resonance imaging, PET imaging, and cognitive function testing. For the quantitative analysis, three-dimensional ROIs were automatically placed, and SUV and SUVR were obtained. We compared these values between AD and healthy control (HC) groups.

RESULTS

SUVR data obtained using the pons and corpus callosum as reference regions strongly correlated with that using the cerebellar cortex. The sensitivity and specificity were high when either the pons or corpus callosum was used as the reference region. However, the SUV values of the corpus callosum were different between AD and HC (p < 0.01).

CONCLUSIONS

Our data suggest that the pons and corpus callosum might be valid reference regions.