Serum and cerebrospinal fluid neurofilament light chain and glial fibrillary acid protein levels in early and advanced stages of cerebral amyloid Angiopathy.

BACKGROUND: Neurofilament light chain (NFL) is a biomarker for neuroaxonal damage and glial fibrillary acidic protein (GFAP) for reactive astrocytosis. Both processes occur in cerebral amyloid angiopathy (CAA), but studies investigating the potential of NFL and GFAP as markers for CAA are lacking. We aimed to investigate NFL and GFAP as biomarkers for neuroaxonal damage and astrocytosis in CAA. METHODS: For this cross-sectional study serum and cerebrospinal fluid (CSF) samples were collected between 2010 and 2020 from controls, (pre)symptomatic Dutch-type hereditary (D-CAA) mutation-carriers and participants with sporadic CAA (sCAA) from two prospective CAA studies at two University hospitals in the Netherlands. NFL and GFAP levels were measured with Simoa-assays. The association between NFL and GFAP levels and age, cognitive performance (MoCA), CAA-related MRI markers (CAA-CSVD-burden) and Aß40 and Aß42 levels in CSF were assessed with linear regression adjusted for confounders. The control group was divided in age < 55 and ≥55 years to match the specific groups. RESULTS: We included 187 participants: 28 presymptomatic D-CAA mutation-carriers (mean age 40 years), 29 symptomatic D-CAA participants (mean age 58 years), 59 sCAA participants (mean age 72 years), 33 controls < 55 years (mean age 42 years) and 38 controls ≥ 55 years (mean age 65 years). In presymptomatic D-CAA, only GFAP in CSF (7.7*103pg/mL vs. 4.4*103pg/mL in controls; P<.001) was increased compared to controls. In symptomatic D-CAA, both serum (NFL:26.2pg/mL vs. 12.5pg/mL; P=0.008, GFAP:130.8pg/mL vs. 123.4pg/mL; P=0.027) and CSF (NFL:16.8*102pg/mL vs. 7.8*102pg/mL; P=0.01 and GFAP:11.4*103pg/mL vs. 7.5*103pg/mL; P<.001) levels were higher than in controls and serum levels (NFL:26.2pg/mL vs. 6.7pg/mL; P=0.05 and GFAP:130.8pg/mL vs. 66.0pg/mL; P=0.004) were higher than in pre-symptomatic D-CAA. In sCAA, only NFL levels were increased compared to controls in both serum (25.6pg/mL vs. 12.5pg/mL; P=0.005) and CSF (20.0*102pg/mL vs 7.8*102pg/mL; P=0.008). All levels correlated with age. Serum NFL correlated with MoCA (P=0.008) and CAA-CSVD score (P<.001). NFL and GFAP in CSF correlated with Aß42 levels (P=0.01/0.02). CONCLUSIONS: GFAP level in CSF is an early biomarker for CAA and is increased years before symptom onset. NFL and GFAP levels in serum and CSF are biomarkers for advanced CAA.

Temporal Ordering of Biomarkers in Dutch-Type Hereditary Cerebral Amyloid Angiopathy.

BACKGROUND: The temporal ordering of biomarkers for cerebral amyloid angiopathy (CAA) is important for their use in trials and for the understanding of the pathological cascade of CAA. We investigated the presence and abnormality of the most common biomarkers in the largest (pre)symptomatic Dutch-type hereditary CAA (D-CAA) cohort to date. METHODS: We included cross-sectional data from participants with (pre)symptomatic D-CAA and controls without CAA. We investigated CAA-related cerebral small vessel disease markers on 3T-MRI, cerebrovascular reactivity with functional 7T-MRI (fMRI) and amyloid-ß40 and amyloid-ß42 levels in cerebrospinal fluid. We calculated frequencies and plotted biomarker abnormality according to age to form scatterplots. RESULTS: We included 68 participants with D-CAA (59% presymptomatic, mean age, 50 [range, 26-75] years; 53% women), 53 controls (mean age, 51 years; 42% women) for cerebrospinal fluid analysis and 36 controls (mean age, 53 years; 100% women) for fMRI analysis. Decreased cerebrospinal fluid amyloid-ß40 and amyloid-ß42 levels were the earliest biomarkers present: all D-CAA participants had lower levels of amyloid-ß40 and amyloid-ß42 compared with controls (youngest participant 30 years). Markers of nonhemorrhagic injury (>20 enlarged perivascular spaces in the centrum semiovale and white matter hyperintensities Fazekas score, ≥2, present in 83% [n=54]) and markers of impaired cerebrovascular reactivity (abnormal BOLD amplitude, time to peak and time to baseline, present in 56% [n=38]) were present from the age of 30 years. Finally, markers of hemorrhagic injury were present in 64% (n=41) and only appeared after the age of 41 years (first microbleeds and macrobleeds followed by cortical superficial siderosis). CONCLUSIONS: Our results suggest that amyloid biomarkers in cerebrospinal fluid are the first to become abnormal in CAA, followed by MRI biomarkers for cerebrovascular reactivity and nonhemorrhagic injury and lastly hemorrhagic injury. This temporal ordering probably reflects the pathological stages of CAA and should be taken into account when future therapeutic trials targeting specific stages are designed.

The relation between vascular risk factors and flow in cerebral perforating arteries. A 7 Tesla MRI study.

INTRODUCTION: Cerebral perforating arteries provide blood supply to the deep regions of the brain. Recently, it became possible to measure blood flow velocity and pulsatility in these small arteries. It is unknown if vascular risk factors are related to these measures. METHODS: We measured perforating artery flow with 2D phase contrast 7 Tesla MRI at the level of the centrum semiovale (CSO) and the basal ganglia (BG) in seventy participants from the Heart Brain Connection study with carotid occlusive disease (COD), vascular cognitive impairment (VCI), or no actual cerebrovascular disease. Vascular risk factors included hypertension, diabetes, hyperlipidemia and smoking. RESULTS: No consistent relations were found between any of the vascular risk factors and either flow velocity or flow pulsatility, although there was a relation between lower diastolic blood pressure and higher pulse pressure and higher cerebral perforator pulsatility (p=0,045 and p=0,044, respectively) at the BG level. Results were similar in stratified analyses for patients with and without a history of cardiovascular disease, or only COD or VCI. CONCLUSION: We conclude that, cross-sectionally, cerebral perforating artery flow velocity and pulsatility are largely independent of the presence of common vascular risk factors in a population with a mixed vascular burden.

Microstructural white matter integrity in relation to vascular reactivity in Dutch-type hereditary cerebral amyloid angiopathy.

Cerebral Amyloid Angiopathy (CAA) is characterized by cerebrovascular amyloid-ß accumulation leading to hallmark cortical MRI markers, such as vascular reactivity, but white matter is also affected. By studying the relationship in different disease stages of Dutch-type CAA (D-CAA), we tested the relation between vascular reactivity and microstructural white matter integrity loss. In a cross-sectional study in D-CAA, 3 T MRI was performed with Blood-Oxygen-Level-Dependent (BOLD) fMRI upon visual activation to assess vascular reactivity and diffusion tensor imaging to assess microstructural white matter integrity through Peak Width of Skeletonized Mean Diffusivity (PSMD). We assessed the relationship between BOLD parameters - amplitude, time-to-peak (TTP), and time-to-baseline (TTB) - and PSMD, with linear and quadratic regression modeling. In total, 25 participants were included (15/10 pre-symptomatic/symptomatic; mean age 36/59 y). A lowered BOLD amplitude (unstandardized ß = 0.64, 95%CI [0.10, 1.18], p = 0.02, Adjusted R2 = 0.48), was quadratically associated with increased PSMD levels. A delayed BOLD response, with prolonged TTP (ß = 8.34 × 10-6, 95%CI [1.84 × 10-6, 1.48 × 10-5], p = 0.02, Adj. R2 = 0.25) and TTB (ß = 6.57 × 10-6, 95%CI [1.92 × 10-6, 1.12 × 10-5], p = 0.008, Adj. R2 = 0.29), was linearly associated with increased PSMD. In D-CAA subjects, predominantly in the symptomatic stage, impaired cerebrovascular reactivity is related to microstructural white matter integrity loss. Future longitudinal studies are needed to investigate whether this relation is causal.

Impact of region of interest definition on visual stimulation-based cerebral vascular reactivity functional MRI with a special focus on applications in cerebral amyloid angiopathy.

Cerebral vascular reactivity quantified using blood oxygen level-dependent functional MRI in conjuncture with a visual stimulus has been proven to be a potent and early marker for cerebral amyloid angiopathy. This work investigates the influence of different postprocessing methods on the outcome of such vascular reactivity measurements. Three methods for defining the region of interest (ROI) over which the reactivity is measured are investigated: structural (transformed V1), functional (template based on the activation of a subset of subjects), and percentile (11.5 cm3 most responding voxels). Evaluation is performed both in a test-retest experiment in healthy volunteers (N = 12), as well as in 27 Dutch-type cerebral amyloid angiopathy patients and 33 age- and sex-matched control subjects. The results show that the three methods select a different subset of voxels, although all three lead to similar outcome measures in healthy subjects. However, in (severe) pathology, the percentile method leads to higher reactivity measures than the other two, due to circular analysis or "double dipping" by defining a subject-specific ROI based on the strongest responses within each subject. Furthermore, while different voxels are included in the presence of lesions, this does not necessarily result in different outcome measures. In conclusion, to avoid bias created by the method, either a structural or a functional method is recommended. Both of these methods provide similar reactivity measures, although the functional ROI appears to be less reproducible between studies, because slightly different subsets of voxels were found to be included. On the other hand, the functional method did include fewer lesion voxels than the structural method.

Subarachnoid CSF hyperintensities at 7 tesla FLAIR MRI: A novel marker in cerebral amyloid angiopathy.

BACKGROUND: We observed subarachnoid cerebrospinal fluid (CSF) hyperintensities at non-contrast 7-tesla (T) fluid-attenuated inversion recovery (FLAIR) MRI, frequently topographically associated with cortical superficial siderosis (cSS), in participants with cerebral amyloid angiopathy (CAA). To systemically evaluate these CSF hyperintensities we investigated their frequency and anatomical and temporal relationship with cSS on 7T and 3T MRI in hereditary Dutch-type CAA (D-CAA), sporadic CAA (sCAA), and non-CAA controls. METHODS: CAA participants were included from two prospective natural history studies and non-CAA controls from a 7T study in healthy females and females with ischemic stroke. CSF hyperintensities were scored by two independent observers. RESULTS: We included 38 sCAA participants (mean age 72y), 50 D-CAA participants (mean age 50y) and 44 non-CAA controls (mean age 53y, 15 with stroke). In total 27/38 (71 %, 95 %CI 56-84) sCAA and 23/50 (46 %, 95 %CI 33-60) D-CAA participants had subarachnoid CSF hyperintensities at baseline 7T. Most (96 %) of those had cSS, in 54 % there was complete topographical overlap with cSS. The remaining 46 % had ≥1 sulcus with CSF hyperintensities without co-localizing cSS. None of the healthy controls and 2/15 (13 %, 95 %CI 2-41, 100 % cSS overlap) of the stroke controls had CSF hyperintensities. In 85 % of the CAA participants CSF hyperintensities could retrospectively be identified at 3T. Of the 35 CAA participants with follow-up 7T after two years, 17/35 (49 %) showed increase and 6/35 (17 %) decrease of regional CSF hyperintensities. In 2/11 (18 %) of participants with follow-up who had baseline CSF hyperintensities without overlapping cSS, new cSS developed at those locations. CONCLUSIONS: Subarachnoid CSF hyperintensities at 7T FLAIR MRI occur frequently in CAA and are associated with cSS, although without complete overlap. We hypothesize that the phenomenon could be a sign of subtle plasma protein or blood product leakage into the CSF, resulting in CSF T1-shortening.

Sex Differences in Onset and Progression of Cerebral Amyloid Angiopathy.

BACKGROUND: Cerebral Amyloid Angiopathy (CAA) disease course is highly variable even in hereditary forms. Sex may be a possible modifying factor. We investigated biological sex differences in clinical disease course and magnetic resonance imaging-markers in sporadic (sCAA) and Dutch-type hereditary CAA (D-CAA). METHODS: Patients with D-CAA and sCAA were included from hospital and research databases of the Leiden University Medical Center (2012-2020) and Massachusetts General Hospital (1994-2012). Key outcomes were: sex differences in symptomatic intracerebral hemorrhage (sICH) onset, recurrence and survival (analyzed using Kaplan Meier survival and regression analyses), and sex differences in magnetic resonance imaging-markers in D-CAA (explored using scatterplots), and in sCAA (investigated using regression analysis). RESULTS: We included 136 patients with D-CAA (mean age 57 years, 56% women, 64% with previous sICH) and 370 patients with sCAA (mean age 76 years, 51% women, all with previous sICH). Men and women with D-CAA did not differ for sICH onset (median age 54 in men and 56 in women [P=0.13]). Men with D-CAA had a slightly higher number of sICH compared with women (median 2 versus 1; adjusted RR, 1.5 [95% CI, 1.1-1.9]) and a shorter interval between the first and second sICH (median 1.8 years for men and 3.1 years for women, P=0.02). Men with sCAA had their first sICH at an earlier age (median 75 versus 78 years, respectively, P=0.003) and more lobar microbleeds (median 1 versus 0, P=0.022) compared with women with sCAA. No substantial differences were found in the other magnetic resonance imaging markers. Survival after first sICH was comparable between sexes for D-CAA (P=0.12) and sCAA (P=0.23). CONCLUSIONS: Men with CAA seem to have an earlier onset (sCAA) and more hemorrhagic disease course (sCAA and D-CAA) compared with women. Future studies are necessary to confirm these findings and determine the underlying role of sex-related factors.

Brain Deep Medullary Veins on 7T MRI in Dutch-Type Hereditary Cerebral Amyloid Angiopathy.

BACKGROUND: Deep medullary vein (DMV) changes occur in cerebral small vessel diseases (SVD) and in Alzheimer's disease. Cerebral amyloid angiopathy (CAA) is a common SVD that has a high co-morbidity with Alzheimer's disease. So far, DMVs have not been evaluated in CAA. OBJECTIVE: To evaluate DMVs in Dutch-type hereditary CAA (D-CAA) mutation carriers and controls, in relation to MRI markers associated with D-CAA. METHODS: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density were quantified on 7 Tesla 3D susceptibility weighted MRI in pre-symptomatic D-CAA mutation carriers (n = 8), symptomatic D-CAA mutation carriers (n = 8), and controls (n = 25). Hemorrhagic MRI markers (cerebral microbleeds, intracerebral hemorrhages, cortical superficial siderosis, convexity subarachnoid hemorrhage), non-hemorrhagic MRI markers (white matter hyperintensities, enlarged perivascular spaces, lacunar infarcts, cortical microinfarcts), cortical grey matter perfusion, and diffusion tensor imaging parameters were assessed in D-CAA mutation carriers. Univariate general linear analysis was used to determine associations between DMV parameters and MRI markers. RESULTS: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density did not differ between pre-symptomatic D-CAA mutation carriers, symptomatic D-CAA mutation carriers, and controls. No associations were found between DMV parameters and MRI markers associated with D-CAA. CONCLUSION: This study indicates that vascular amyloid-ß deposition does not affect DMV parameters. In patients with CAA, DMVs do not seem to play a role in the pathogenesis of MRI markers associated with CAA.

The use of variable delay multipulse chemical exchange saturation transfer for separately assessing different CEST pools in the human brain at 7T.

PURPOSE: Current challenges of in vivo CEST imaging include overlapping signals from different pools. The overlap arises from closely resonating pools and/or the broad magnetization transfer contrast (MTC) from macromolecules. This study aimed to evaluate the feasibility of variable delay multipulse (VDMP) CEST to separately assess solute pools with different chemical exchange rates in the human brain in vivo, while mitigating the MTC. METHODS: VDMP saturation buildup curves were simulated for amines, amides, and relayed nuclear Overhauser effect. VDMP data were acquired from glutamate and bovine serum albumin phantoms, and from six healthy volunteers at 7T. For the in vivo data, MTC removal was performed via a three-pool Lorentzian fitting. Different B1 amplitudes and mixing times were used to evaluate CEST pools with different exchange rates. RESULTS: The results show the importance of removing MTC when applying VDMP in vivo and the influence of B1 for distinguishing different pools. Finally, the optimal B1 and mixing times to effectively saturate slow- and fast-exchanging components are also reported. Slow-exchanging amides and rNOE components could be distinguished when using B1 = 1 µT and tmix = 10 ms and 40 ms, respectively. Fast-exchanging components reached the highest saturation when using a B1 = 2.8 µT and tmix = 0 ms. CONCLUSION: VDMP is a powerful CEST-editing tool, exploiting chemical exchange-rate differences. After MTC removal, it allows separate assessment of slow- and fast-exchanging solute pools in in vivo human brain.

Cerebellar Superficial Siderosis in Cerebral Amyloid Angiopathy.

BACKGROUND AND PURPOSE: Although evidence accumulates that the cerebellum is involved in cerebral amyloid angiopathy (CAA), cerebellar superficial siderosis is not considered to be a disease marker. The objective of this study is to investigate cerebellar superficial siderosis frequency and its relation to hemorrhagic magnetic resonance imaging markers in patients with sporadic and Dutch-type hereditary CAA and patients with deep perforating arteriopathy-related intracerebral hemorrhage. METHODS: We recruited patients from 3 prospective 3 Tesla magnetic resonance imaging studies and scored siderosis and hemorrhages. Cerebellar siderosis was identified as hypointense linear signal loss (black) on susceptibility-weighted or T2*-weighted magnetic resonance imaging which follows at least one folia of the cerebellar cortex (including the vermis). RESULTS: We included 50 subjects with Dutch-type hereditary CAA, (mean age 50 years), 45 with sporadic CAA (mean age 72 years), and 43 patients with deep perforating arteriopathy-related intracerebral hemorrhage (mean age 54 years). Cerebellar superficial siderosis was present in 5 out of 50 (10% [95% CI, 2-18]) patients with Dutch-type hereditary CAA, 4/45 (9% [95% CI, 1-17]) patients with sporadic CAA, and 0 out of 43 (0% [95% CI, 0-8]) patients with deep perforating arteriopathy-related intracerebral hemorrhage. Patients with cerebellar superficial siderosis had more supratentorial lobar (median number 9 versus 2, relative risk, 2.9 [95% CI, 2.5-3.4]) and superficial cerebellar macrobleeds (median number 2 versus 0, relative risk, 20.3 [95% CI, 8.6-47.6]) compared with patients without the marker. The frequency of cortical superficial siderosis and superficial cerebellar microbleeds was comparable. CONCLUSIONS: We conclude that cerebellar superficial siderosis might be a novel marker for CAA.

Non-Invasive Assessment of Damping of Blood Flow Velocity Pulsatility in Cerebral Arteries With MRI.

BACKGROUND: Damping of heartbeat-induced pressure pulsations occurs in large arteries such as the aorta and extends to the small arteries and microcirculation. Since recently, 7 T MRI enables investigation of damping in the small cerebral arteries. PURPOSE: To investigate flow pulsatility damping between the first segment of the middle cerebral artery (M1) and the small perforating arteries using magnetic resonance imaging. STUDY TYPE: Retrospective. SUBJECTS: Thirty-eight participants (45% female) aged above 50 without history of heart failure, carotid occlusive disease, or cognitive impairment. FIELD STRENGTH/SEQUENCE: 3 T gradient echo (GE) T1-weighted images, spin-echo fluid-attenuated inversion recovery images, GE two-dimensional (2D) phase-contrast, and GE cine steady-state free precession images were acquired. At 7 T, T1-weighted images, GE quantitative-flow, and GE 2D phase-contrast images were acquired. ASSESSMENT: Velocity pulsatilities of the M1 and perforating arteries in the basal ganglia (BG) and semi-oval center (CSO) were measured. We used the damping index between the M1 and perforating arteries as a damping indicator (velocity pulsatilityM1 /velocity pulsatilityCSO/BG ). Left ventricular stroke volume (LVSV), mean arterial pressure (MAP), pulse pressure (PP), and aortic pulse wave velocity (PWV) were correlated with velocity pulsatility in the M1 and in perforating arteries, and with the damping index of the CSO and BG. STATISTICAL TESTS: Correlations of LVSV, MAP, PP, and PWV with velocity pulsatility in the M1 and small perforating arteries, and correlations with the damping indices were evaluated with linear regression analyses. RESULTS: PP and PWV were significantly positively correlated to M1 velocity pulsatility. PWV was significantly negatively correlated to CSO velocity pulsatility, and PP was unrelated to CSO velocity pulsatility (P = 0.28). PP and PWV were uncorrelated to BG velocity pulsatility (P = 0.25; P = 0.68). PWV and PP were significantly positively correlated with the CSO damping index. DATA CONCLUSION: Our study demonstrated a dynamic damping of velocity pulsatility between the M1 and small cerebral perforating arteries in relation to proximal stress. LEVEL OF EVIDENCE: 4 TECHNICAL EFFICACY: Stage 1.

Occipital Cortical Calcifications in Cerebral Amyloid Angiopathy.

Background and Purpose: Cortical calcifications have been reported in patients with cerebral amyloid angiopathy (CAA), although their prevalence and pathophysiology are unknown. We investigated the frequency of calcifications on computed tomography, their association with intracerebral hemorrhage (ICH) and their coexistence with a striped pattern of the occipital cortex reflecting microcalcifications on ultra-high-field 7T-magnetic resonance imaging in Dutch-type hereditary CAA (D-CAA) and sporadic CAA. Methods: We included D-CAA mutation carriers with a proven APP (amyloid precursor protein) mutation or ≥1 lobar ICH and ≥1 first-degree relative with D-CAA and sporadic CAA patients with probable CAA according to the modified Boston criteria. D-CAA carriers were regarded symptomatic when they had a history of symptomatic ICH. We assessed the presence, location, and progression of calcifications and their association with ICH and the striped occipital cortex. Results: We found cortical calcifications in 15/81 (19% [95% CI, 11­29]) D-CAA mutation carriers (15/69 symptomatic and 0/12 presymptomatic) and in 1/59 (2% [95% CI, 0­9]) sporadic CAA patients. Calcifications were all bilateral located in the occipital lobes. In 3/15 (20%) of the symptomatic D-CAA patients the calcifications progressed over a period up to 10 years. There was evidence of an association between cortical calcifications and new ICH development (hazard ratio, 7.1 [95% CI, 0.9­54.9], log-rank P=0.03). In 7/25 D-CAA symptomatic carriers in whom a 7T-magnetic resonance imaging was performed, a striped pattern of the occipital cortex was present; in 3/3 (100%) of those with calcifications on computed tomography and 4/22 (18%) of those without calcifications. Conclusions: Occipital cortical calcifications are frequent in D-CAA but seem to be rare in sporadic CAA. Their absence in presymptomatic carriers and their association with ICH might suggest that they are a marker for advanced CAA. Cortical calcifications on computed tomography seem to be associated with the striped occipital cortex on 7T-magnetic resonance imaging which may possibly represent an early stage of calcification.

Quantitative susceptibility mapping in the thalamus and basal ganglia of systemic lupus erythematosus patients with neuropsychiatric complaints.

Systemic lupus erythematosus (SLE) is an auto-immune disease characterized by multi-organ involvement. Although uncommon, central nervous system involvement in SLE, termed neuropsychiatric SLE (NPSLE), is not an exception. Current knowledge on underlying pathogenic mechanisms is incomplete, however, neuroinflammation is thought to play a critical role. Evidence from neurodegenerative diseases and multiple sclerosis suggests that neuroinflammation is correlated with brain iron accumulation, making quantitative susceptibility mapping (QSM) a potential hallmark for neuroinflammation in vivo. This study assessed susceptibility values of the thalamus and basal ganglia in (NP)SLE patients and further investigated the in vivo findings with histological analyses of postmortem brain tissue derived from SLE patients. We used a 3T MRI scanner to acquire single-echo T2*-weighted images of 44 SLE patients and 20 age-matched healthy controls. Of the 44 patients with SLE, all had neuropsychiatric complaints, of which 29 were classified as non-NPSLE and 15 as NPSLE (seven as inflammatory NPSLE and eight as ischemic NPSLE). Mean susceptibility values of the thalamus, caudate nucleus, putamen, and globus pallidus were calculated. Formalin-fixed paraffin-embedded post-mortem brain tissue including the putamen and globus pallidus of three additional SLE patients was obtained and stained for iron, microglia and astrocytes. Susceptibility values of SLE patients and age-matched controls showed that iron levels in the thalamus and basal ganglia were not changed due to the disease. No subgroup of SLE showed higher susceptibility values. No correlation was found with disease activity or damage due to SLE. Histological examination of the post-mortem brain showed no increased iron accumulation. Our results suggest that neuroinflammation in NPSLE does not necessarily go hand in hand with iron accumulation, and that the inflammatory pathomechanism in SLE may differ from the one observed in neurodegenerative diseases and in multiple sclerosis.

Histopathology of diffusion-weighted imaging-positive lesions in cerebral amyloid angiopathy.

Small subclinical hyperintense lesions are frequently encountered on brain diffusion-weighted imaging (DWI) scans of patients with cerebral amyloid angiopathy (CAA). Interpretation of these DWI+ lesions, however, has been limited by absence of histopathological examination. We aimed to determine whether DWI+ lesions represent acute microinfarcts on histopathology in brains with advanced CAA, using a combined in vivo MRI-ex vivo MRI-histopathology approach. We first investigated the histopathology of a punctate cortical DWI+ lesion observed on clinical in vivo MRI 7 days prior to death in a CAA case. Subsequently, we assessed the use of ex vivo DWI to identify similar punctate cortical lesions post-mortem. Intact formalin-fixed hemispheres of 12 consecutive cases with CAA and three non-CAA controls were subjected to high-resolution 3 T ex vivo DWI and T2 imaging. Small cortical lesions were classified as either DWI+/T2+ or DWI-/T2+. A representative subset of lesions from three CAA cases was selected for detailed histopathological examination. The DWI+ lesion observed on in vivo MRI could be matched to an area with evidence of recent ischemia on histopathology. Ex vivo MRI of the intact hemispheres revealed a total of 130 DWI+/T2+ lesions in 10/12 CAA cases, but none in controls (p = 0.022). DWI+/T2+ lesions examined histopathologically proved to be acute microinfarcts (classification accuracy 100%), characterized by presence of eosinophilic neurons on hematoxylin and eosin and absence of reactive astrocytes on glial fibrillary acidic protein-stained sections. In conclusion, we suggest that small DWI+ lesions in CAA represent acute microinfarcts. Furthermore, our findings support the use of ex vivo DWI as a method to detect acute microinfarcts post-mortem, which may benefit future histopathological investigations on the etiology of microinfarcts.

Cerebrovascular function in presymptomatic and symptomatic individuals with hereditary cerebral amyloid angiopathy: a case-control study.

BACKGROUND: Previous work suggests that impairments of cerebrovascular flow or reactivity might be early markers of cerebral amyloid angiopathy (CAA). Hereditary cerebral haemorrhage with amyloidosis-Dutch type (HCHWA-D) is a genetic form of CAA that can be diagnosed before the onset of clinical symptoms by DNA testing. We aimed to investigate whether haemodynamic measures are decreased in presymptomatic and symptomatic HCHWA-D mutation carriers compared with healthy controls. METHODS: In this case-control study, we included presymptomatic and symptomatic HCHWA-D mutation carriers diagnosed through genetic testing and recruited through the HCHWA-D patient association (Katwijk, Netherlands) and the outpatient clinic of the Department of Neurology of the Leiden University Medical Center (Leiden, Netherlands), and healthy controls. We measured regional cerebral blood flow (rCBF) using pseudo-continuous arterial spin labelling. Quantitative flow was measured by phase-contrast magnetic resonance angiography of the cerebropetal vessels. Vascular reactivity was established by measuring changes in blood-oxygen-level-dependent (BOLD) signal after visual stimulation. Data from presymptomatic and symptomatic individuals were compared with healthy controls using mixed-model regression analysis. FINDINGS: Between May 15, 2012, and December 22, 2015, we investigated cross-sectional imaging data from 27 HCHWA-D mutation carriers (12 presymptomatic and 15 symptomatic) and 33 healthy controls. Compared with controls, symptomatic HCHWA-D carriers had significantly decreased cortical grey matter rCBF in the occipital lobe (mean difference -11·1 mL/100 g per min, 95% CI -2·8 to -19·3; uncorrected p=0·010) and decreased flux in the basilar artery (mean difference -0·9 mL/s, 95% CI -1·5 to -0·2; uncorrected p=0·019). However, we noted no changes in rCBF and flux in presymptomatic carriers compared with controls. Vascular reactivity was significantly decreased in the occipital lobe in both presymptomatic (mean BOLD change 1·1% [SD 0·5], mean difference -0·4% change, 95% CI -0·7 to -0·2; p=0·001; mean time to baseline 10·1 s [SD 7·6], mean difference 4·6 s, 95% CI 0·4 to 8·8; p=0·032) and symptomatic carriers (mean BOLD change 0·4% [SD 0·1], mean difference -0·9%, 95% CI -1·1 to -0·6; p<0·0001; mean time to baseline 20·3 s [SD 8·4], mean difference 13·1 s, 95% CI 9·4 to 16·9; p<0·0001) compared with controls; however, the difference in mean time to peak was only significant for symptomatic carriers (mean difference 12·2 s, 95% CI 8·6 to 15·9; p<0·0001). INTERPRETATION: Our findings suggest that determination of vascular reactivity might be a useful biomarker for early detection of vascular amyloid pathology in sporadic CAA, and a biomarker of efficacy in future intervention trials. Our data indicate that vascular reactivity measurements might be useful for differential diagnosis in dementia to determine the vascular component. FUNDING: USA National Institutes of Health.