Cerebral Amyloid Angiopathy: CT and MR Imaging Findings

Deciphering the role of APOE in cerebral amyloid angiopathy: from genetic insights to therapeutic horizons

Cerebral amyloid angiopathy (CAA), characterized by the deposition of amyloid-β (Aβ) peptides in the walls of medium and small vessels of the brain and leptomeninges, is a major cause of lobar hemorrhage in elderly individuals. Among the genetic risk factors for CAA that continue to be recognized, the apolipoprotein E (APOE) gene is the most significant and prevalent, as its variants have been implicated in more than half of all patients with CAA. While the presence of the APOE ε4 allele markedly increases the risk of CAA, the ε2 allele confers a protective effect relative to the common ε3 allele. These allelic variants encode three APOE isoforms that differ at two amino acid positions. The primary physiological role of APOE is to mediate lipid transport in the brain and periphery; however, it has also been shown to be involved in a wide array of biological functions, particularly those involving Aβ, in which it plays a known role in processing, production, aggregation, and clearance. The challenges posed by the reliance on postmortem histological analyses and the current absence of an effective intervention underscore the urgency for innovative APOE-targeted strategies for diagnosing CAA. This review not only deepens our understanding of the impact of APOE on the pathogenesis of CAA but can also help guide the exploration of targeted therapies, inspiring further research into the therapeutic potential of APOE.

One-Year Radiologic Progression in Sporadic and Hereditary Cerebral Amyloid Angiopathy

BACKGROUND AND OBJECTIVES

Knowledge on the short-term progression of cerebral amyloid angiopathy (CAA) is important for clinical practice and the design of clinical treatment trials. We investigated the 1-year progression of CAA-related MRI markers in sporadic (sCAA) and Dutch-type hereditary (D-CAA).

METHODS

Participants were included from 2 prospective cohort studies. 3T-MRI was performed at baseline and after 1 year. We assessed macrobleeds, cerebral microbleeds (CMBs), cortical superficial siderosis (cSS), convexity subarachnoid hemorrhages (cSAHs), white matter hyperintensities (WMH), enlarged centrum semiovale perivascular spaces (CSO-EPVS), and visually stimulated blood oxygenation level-dependent (BOLD) fMRI parameters. Progression was defined as increase in number of macrobleeds or CMBs, new focus or extension of cSS, increase in CSO-EPVS category, or volume increase of >10% of WMH. Multivariable regression analyses were performed to determine factors associated with progression and the association between events related to parenchymal injury (cSAH, macrobleeds) and radiologic progression.

RESULTS

We included 98 participants (47% women): 55 with sCAA (mean age 70 years), 28 with symptomatic D-CAA (mean age 59 years), and 15 with presymptomatic D-CAA (mean age 45 years). Progression of >1 MRI markers was seen in all 83 (100%) participants with sCAA and symptomatic D-CAA and in 9 (60%) with presymptomatic D-CAA. The number of CMBs showed the largest progression in sCAA (98%; median increase 24) and symptomatic D-CAA (100%; median increase 58). WMH volume (>10% increase in 70%; mean increase 1.2 mL) was most progressive in presymptomatic D-CAA. A decrease in the upslope of the visually evoked BOLD response was observed for most patients. Symptomatic D-CAA status was associated with more overall progression (adjusted odds ratio [aOR] 9.7; 95% CI 1.7-54.2), CMB (adjusted relative risk [aRR] 2.47; 95% CI 1.5-4.1), and WMH volume progression (β 2.52; 95% CI 0.3-4.8). Baseline CMB count (aRR 1.002; 95% CI 1.001-1.002) was associated with CMB progression and cSS presence at baseline (aOR 8.16; 95% CI 2.6-25.4) with cSS progression. cSS progression was also associated with cSAH and macrobleeds (aOR 21,029; 95% CI 2.042-216.537).

DISCUSSION

CAA is a radiologically progressive disease even in the short-term. After 1 year, all symptomatic and most of the presymptomatic participants showed progression of at least 1 MRI-marker. CMBs and WMH volume (in symptomatic CAA) and WMH volume (in presymptomatic CAA) are the most promising markers to track short-term progression in future trials.

Real-world application of a 3D deep learning model for detecting and localizing cerebral microbleeds

BACKGROUND

Detection and localization of cerebral microbleeds (CMBs) is crucial for disease diagnosis and treatment planning. However, CMB detection is labor-intensive, time-consuming, and challenging owing to its visual similarity to mimics. This study aimed to validate the performance of a three-dimensional (3D) deep learning model that not only detects CMBs but also identifies their anatomic location in real-world settings.

METHODS

A total of 21 patients with 116 CMBs and 12 without CMBs were visited in the neurosurgery outpatient department between January 2023 and October 2023. Three readers, including a board-certified neuroradiologist (reader 1), a resident in radiology (reader 2), and a neurosurgeon (reader 3) independently reviewed SWIs of 33 patients to detect CMBs and categorized their locations into lobar, deep, and infratentorial regions without any AI assistance. After a one-month washout period, the same datasets were redistributed randomly, and readers reviewed them again with the assistance of the 3D deep learning model. A comparison of the diagnostic performance between readers with and without AI assistance was performed.

RESULTS

All readers with an AI assistant (reader 1:0.991 [0.930-0.999], reader 2:0.922 [0.881-0.905], and reader 3:0.966 [0.928-0.984]) tended to have higher sensitivity per lesion than readers only (reader 1:0.905 [0.849-0.942], reader 2:0.621 [0.541-0.694], and reader 3:0.871 [0.759-0.935], p = 0.132, 0.017, and 0.227, respectively). In particular, radiology residents (reader 2) showed a statistically significant increase in sensitivity per lesion when using AI. There was no statistically significant difference in the number of FPs per patient for all readers with AI assistant (reader 1: 0.394 [0.152-1.021], reader 2: 0.727 [0.334-1.582], reader 3: 0.182 [0.077-0.429]) and reader only (reader 1: 0.364 [0.159-0.831], reader 2: 0.576 [0.240-1.382], reader 3: 0.121 [0.038-0.383], p = 0.853, 0.251, and 0.157, respectively). Our model accurately categorized the anatomical location of all CMBs.

CONCLUSIONS

Our model demonstrated promising potential for the detection and anatomical localization of CMBs, although further research with a larger and more diverse population is necessary to establish clinical utility in real-world settings.

Cerebral Amyloid Angiopathy: An Undeniable Small Vessel Disease

Cerebral amyloid angiopathy (CAA) has been proven to be the most common pathological change in cerebral small vessel disease except arteriosclerosis. In recent years, with the discovery of imaging technology and new imaging markers, the diagnostic rate of CAA has greatly improved. CAA plays an important role in non-hypertensive cerebral hemorrhage and cognitive decline. This review comprehensively describes the etiology, epidemiology, pathophysiological mechanisms, clinical features, imaging manifestations, imaging markers, diagnostic criteria, and treatment of CAA to facilitate its diagnosis and treatment and reduce mortality.

Exploring cerebral amyloid angiopathy: Insights into pathogenesis, diagnosis, and treatment

Cerebral Amyloid Angiopathy (CAA) is a neurological disorder characterized by the deposition of amyloid plaques in the walls of cerebral blood vessels. This condition poses significant challenges in terms of understanding its underlying mechanisms, accurate diagnosis, and effective treatment strategies. This article aims to shed light on the complexities of CAA by providing insights into its pathogenesis, diagnosis, and treatment options. The pathogenesis of CAA involves the accumulation of amyloid beta (Aβ) peptides in cerebral vessels, leading to vessel damage, impaired blood flow, and subsequent cognitive decline. Various genetic and environmental factors contribute to the development and progression of CAA, and understanding these factors is crucial for targeted interventions. Accurate diagnosis of CAA often requires advanced imaging techniques, such as magnetic resonance imaging (MRI) or positron emission tomography (PET) scans, to detect characteristic amyloid deposits in the brain. Early and accurate diagnosis enables appropriate management and intervention strategies. Treatment of CAA focuses on preventing further deposition of amyloid plaques, managing associated symptoms, and reducing the risk of complications such as cerebral hemorrhage. Currently, there are no disease-modifying therapies specifically approved for CAA. However, several experimental treatments targeting Aβ clearance and anti-inflammatory approaches are being investigated in clinical trials, offering hope for future therapeutic advancements.

Inflammatory Cerebral Amyloid Angiopathy: A Broad Clinical Spectrum

Cerebral amyloid angiopathy (CAA) is a common central nervous system (CNS) vasculopathy, which in some cases is associated with subacute encephalopathy, seizures, headaches, or strokes due to vascular inflammation directed against vascular amyloid accumulation. The pathological subtypes of inflammatory CAA include CAA-related inflammation (CAAri) with mostly perivascular lymphocytic infiltrates, or amyloid-beta (Aβ)-related angiitis (ABRA) with transmural granulomatous inflammation. CAAri and ABRA probably represent part of the spectrum of CNS vasculopathies, intermediate between CAA and primary CNS vasculitis, and they are closely related to Aβ-related imaging abnormalities and other manifestations of an inflammatory response directed against Aβ in the leptomeninges and cerebral parenchyma. As treatment strategies in Alzheimer's disease shift toward potentially effective antiamyloid immunotherapy, the incidence rate of inflammatory CAA (which is probably an underrecognized condition) is likely to increase. Its clinical features are varied and include subacute encephalopathy, behavioral symptoms, headaches, seizures, and focal neurological deficits, which necessitate a high degree of suspicion for this disorder that often responds to treatment. The recent definition of the typical clinical and radiological syndrome has increased its recognition and may eliminate the need for invasive histological sampling in at least some affected patients. Here we review the pathophysiology, clinical spectrum, and approach to diagnosis, and discuss illustrative cases that highlight the wide range of clinical presentations.

Automated detection of cerebral microbleeds via segmentation in susceptibility-weighted images of patients with traumatic brain injury

Cerebral microbleeds (CMBs) are a recognised biomarker of traumatic axonal injury (TAI). Their number and location provide valuable information in the long-term prognosis of patients who sustained a traumatic brain injury (TBI). Accurate detection of CMBs is necessary for both research and clinical applications. CMBs appear as small hypointense lesions on susceptibility-weighted magnetic resonance imaging (SWI). Their size and shape vary markedly in cases of TBI. Manual annotation of CMBs is a difficult, error-prone, and time-consuming task. Several studies addressed the detection of CMBs in other neuropathologies with convolutional neural networks (CNNs). In this study, we developed and contrasted a classification (Patch-CNN) and two segmentation (Segmentation-CNN, U-Net) approaches for the detection of CMBs in TBI cases. The models were trained using 45 datasets, and the best models were chosen according to 16 validation sets. Finally, the models were evaluated on 10 TBI and healthy control cases, respectively. Our three models outperform the current status quo in the detection of traumatic CMBs, achieving higher sensitivity at low false positive (FP) counts. Furthermore, using a segmentation approach allows for better precision. The best model, the U-Net, achieves a detection rate of 90% at FP counts of 17.1 in TBI patients and 3.4 in healthy controls.

Nontraumatic brain parenchymal hemorrhage: The usual suspects and more

Brain parenchymal hemorrhage is a common neuroimaging finding in an emergency room. It is considered primary in the absence of an underlying lesion or coagulopathy. Secondary hemorrhages are caused by various structural causes and pathologies. The goals of imaging are to identify the hematoma, assess factors that have prognostic significance, assess associated complications, identify an underlying etiology whenever possible, and guide therapeutic decisions. The review provides an illustrative review of various etiologies of non-traumatic brain parenchymal hemorrhage and their imaging evaluation.

Clinical and radiological evolution of cerebral amyloid angiopathy-related inflammation in the context of anti-PD-1 immunotherapy

Immune-related adverse events (irAEs) are a frequent complication of immunotherapy, but neurological irAEs are rare and varied. Here, we present a case of cerebral amyloid angiopathy-related inflammation (CAA-ri) attributable to nivolumab monotherapy, which has not been previously reported. The context of immunotherapy and availability of serial imaging also provide unique insights into the pathogenesis and evolution of CAA-ri. Routine surveillance neuroimaging in a patient with metastatic melanoma, in remission after treatment with nivolumab, demonstrated progressive microhaemorrhages and associated oedema, suspicious for CAA-ri. These changes progressed despite cessation of nivolumab. The patient was initially asymptomatic, but later developed an acute confusional state, warranting brain biopsy, which confirmed the diagnosis of CAA-ri. Treatment with methylprednisolone resulted in resolution of the oedema, and a marked decrease in the subsequent accumulation of microhaemorrhages. The temporal evolution prior to symptom development and subsequently related to treatment suggests that inflammation may be an important component of the pathogenesis of CAA-ri, rather than simply a secondary response. Given that immunotherapy is in its relative infancy, it is important to consider rare irAEs in patients exhibiting unusual imaging findings.

Cerebral Amyloid Angiopathy and the Fibrinolytic System: Is Plasmin a Therapeutic Target?

Cerebral amyloid angiopathy is a devastating cause of intracerebral hemorrhage for which there is no specific secondary stroke prevention treatment. Here we review the current literature regarding cerebral amyloid angiopathy pathophysiology and treatment, as well as what is known of the fibrinolytic pathway and its interaction with amyloid. We postulate that tranexamic acid is a potential secondary stroke prevention treatment agent in sporadic cerebral amyloid angiopathy, although further research is required.

Cerebral Amyloid Angiopathy with Cortical Subarachnoid Hemorrhage as a Mimic for Transient Ischemic Attack: A Case Report

Context: Given its cerebral amyloid angiopathy, subarachnoid hemorrhage might represent transient focal neurological episodes erroneously diagnosed as transient ischemic attacks. The earliest neuroimaging findings in emergency room brain computed tomography indicating subarachnoid hemorrhage in these patients might be very subtle and missed by the clinician. Case Presentation: An 80-year-old man referred with transient focal neurological episodes, suggestive of transient ischemic attacks. In general, except for some cognitive dysfunctions, no remarkable point was noticed in his neurological examination. Non-enhanced brain-computer tomography and magnetic resonance imaging revealed evidence indicating slight convexity subarachnoid hemorrhage at the left frontal cortical region. Conclusions: The transient focal neurological episodes uncommonly represent intracranial hemorrhage. Nevertheless, this clinical representation might occur in patients with subarachnoid hemorrhage due to cerebral amyloid angiopathy. In such cases, the neuroimaging findings play a major role in the differential diagnosis. The misdiagnosis of transient ischemic attacks in these cases might lead to the consumption of antiplatelet drugs and end in catastrophic hemorrhage and life-threatening complications. Close attention to patients' clinical findings and judicious use of further neuroimaging studies would help clinicians to avoid making such mistakes.

Young plasma attenuates cognitive impairment and the cortical hemorrhage area in cerebral amyloid angiopathy model mice

Background

Cerebral amyloid angiopathy (CAA) is characterized by the deposition of β-amyloid (Aβ) in leptomeningeal vessels and penetrating arterioles. Intracerebral hemorrhage (ICH) is one of the most destructive complications in CAA. Young plasma has been shown to improve cognitive, learning, and memory functions in Alzheimer’s disease (AD) model mice and is a new potential therapy. However, it is not clear whether young plasma can reduce cerebral hemorrhage and improve the prognosis of neurological function in APP/PS1 (which express APP695swe and PS1-dE9 mutations) mice with CAA disease.

Methods

The Y-maze, new object recognition (NOR), forced swimming, open field, sucrose consumption, and corner tests were used to evaluate the learning and memory, cognitive ability, and emotional changes in CAA model mice. The effect of young plasma on neurogenesis was analyzed by immunofluorescence. The level of Aβ in the cerebral cortex and hippocampus of mice was measured by enzyme-linked immunosorbent assay (ELISA). Finally, the area of cortical hemorrhage in mice was analyzed by fast blue-staining.

Results

We proved that young plasma improved cognition, learning and memory impairment, and anxiety in CAA model mice, prevented neuronal apoptosis, and enhanced neurogenesis in APP/PS1 mice. However, young plasma did not reduce the level of Aβ in the cortex and hippocampus of APP/PS1 mice. We also found that young plasma reduced the area of cerebral hemorrhage in APP/PS1 mice.

Conclusions

Our results show that young plasma can improve learning and memory, cognitive impairment, and anxiety in CAA model mice and can reduce the area of cortical hemorrhage.

Cerebrovascular disease in patients with COVID-19: neuroimaging, histological and clinical description

Since the appearance of the first case of coronavirus disease 2019 (COVID-19) a pandemic has emerged affecting millions of people worldwide. Although the main clinical manifestations are respiratory, an increase in neurological conditions, specifically acute cerebrovascular disease, has been detected. We present cerebrovascular disease case incidence in hospitalized patients with SARS-CoV-2 infection. Patients were confirmed by microbiological/serological testing, or on chest CT semiology. Available data on comorbidity, laboratory parameters, treatment administered, neuroimaging, neuropathological studies and clinical evolution during hospitalization, measured by the modified Rankin scale, were analysed. A bivariate study was also designed to identify differences between ischaemic and haemorrhagic subtypes. A statistical model of binary logistic regression and sensitivity analysis was designed to study the influence of independent variables over prognosis. In our centre, there were 1683 admissions of patients with COVID-19 over 50 days, of which 23 (1.4%) developed cerebrovascular disease. Within this group of patients, cerebral and chest CT scans were performed in all cases, and MRI in six (26.1%). Histological samples were obtained in 6/23 cases (two brain biopsies, and four arterial thrombi). Seventeen patients were classified as cerebral ischaemia (73.9%, with two arterial dissections), five as intracerebral haemorrhage (21.7%), and one leukoencephalopathy of posterior reversible encephalopathy type. Haemorrhagic patients had higher ferritin levels at the time of stroke (1554.3 versus 519.2, P = 0.004). Ischaemic strokes were unexpectedly frequent in the vertebrobasilar territory (6/17, 35.3%). In the haemorrhagic group, a characteristic radiological pattern was identified showing subarachnoid haemorrhage, parieto-occipital leukoencephalopathy, microbleeds and single or multiple focal haematomas. Brain biopsies performed showed signs of thrombotic microangiopathy and endothelial injury, with no evidence of vasculitis or necrotizing encephalitis. The functional prognosis during the hospital period was unfavourable in 73.9% (17/23 modified Rankin scale 4–6), and age was the main predictive variable (odds ratio = 1.5; 95% confidence interval 1.012–2.225; P = 0.043). Our series shows cerebrovascular disease incidence of 1.4% in patients with COVID-19 with high morbidity and mortality. We describe pathological and radiological data consistent with thrombotic microangiopathy caused by endotheliopathy with a haemorrhagic predisposition.

A Pictorial Review of Intracranial Haemorrhage Revisited

BACKGROUND

The many causes of Intracerebral Haemorrhage (IH) can be difficult to differentiate. However, there are imaging features that can provide useful clues. This paper aims to provide a pictorial review of the common causes of IH, to identify some distinguishing diagnostic features and to provide guidance on subsequent imaging and follow up. It is hoped that this review would benefit radiology and non-radiology consultants, multi-professional workers and trainees who are commonly exposed to unenhanced CT head studies but are not neuroradiology specialists.

DISCUSSION

In the absence of trauma, Spontaneous Intracerebral Haemorrhage (SIH) can be classified as idiopathic or secondary. Secondary causes of IH include hypertension and amyloid angiopathy (75-80%) and less common pathologies such as vascular malformations (arteriovenous malformations, aneurysms and cavernomas), malignancy , venous sinus thrombosis and infection. SIH causes between 10 to 15% of all strokes and has a higher mortality than ischaemic stroke. Trauma is another cause of IH with significant mortality and some of the radiological features will be reviewed.

CONCLUSION

Unenhanced CT is a mainstay of acute phase imaging due to its availability and, sensitivity and specificity for detecting acute haemorrhage. Several imaging features can be identified on CT and, along with clinical information, can provide some certainty in diagnosis. For those suitable and where diagnostic uncertainty remains CT angiogram, time-resolved CT angiography and catheter angiography can help identify underlying AVMs, aneurysms, cavernomas and vasculitides. MRI is more sensitive for the detection of subacute and chronic haemorrhage and identification of underlying mass lesions.

Causes of Acute Stroke: A Patterned Approach

Acute stroke is a leading cause of morbidity and mortality in the United States. Acute ischemic strokes have been classified according to The Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification system, and this system aids in proper management. Nearly every patient who presents to a hospital with acute stroke symptoms has some form of emergent imaging. As such, imaging plays an important role in early diagnosis and management. This article reviews the imaging patterns of acute strokes, and how the infarct pattern and imaging characteristics can suggest an underlying cause.

Subarachnoid and Subdural Hemorrhages in Lobar Intracerebral Hemorrhage Associated With Cerebral Amyloid Angiopathy

Background and Purpose- Identifying underlying cerebral amyloid angiopathy (CAA) in patients with intracerebral hemorrhage (ICH) has important clinical implication. Convexity subarachnoid hemorrhage (cSAH) and subdural hemorrhage (SDH) are computed tomography features of CAA-related ICH. We explored whether cSAH and SDH could be additional magnetic resonance imaging markers of CAA in lobar ICH survivors. Methods- We analyzed data from consecutive patients with acute lobar ICH associated with CAA (CAA-ICH) or not attributed to CAA (non-CAA-ICH). Magnetic resonance imaging scans were analyzed for cSAH, SDH, and markers of small vessel disease. The associations of cSAH and SDH with the diagnosis of probable CAA based on the modified Boston criteria were explored using multivariable models. Results- We included 165 patients with acute lobar ICH (mean age 70±13 years): 72 patients with CAA-ICH and 93 with non-CAA-ICH. Patients with CAA-ICH had a higher prevalence of cSAH (73.6% versus 39.8%; P<0.001) and SDH (37.5% versus 21.5%; P=0.02) than non-CAA-ICH. In multivariate logistic regression analysis, the presence of cSAH was independently associated with CAA-ICH (odds ratio, 2.97; 95% CI, 1.26-6.99; P=0.013), whereas there was no association between SDH and CAA-ICH. Conclusions- Among survivors of acute lobar ICH, the presence of cSAH is associated with the magnetic resonance imaging-based diagnosis of CAA. Further studies should investigate whether cSAH help improve the sensitivity of magnetic resonance imaging for in vivo diagnosis of CAA.

Cerebrovascular pathology in cerebral amyloid angiopathy presenting as intracerebral haemorrhage

Cerebral amyloid angiopathy (CAA) is the second most common cause of non-traumatic intracerebral haemorrhage (ICH) accounting for 12-15% of lobar haemorrhages in the elderly. Definitive diagnosis of CAA requires histological evaluation. We aimed to evaluate the spectrum of cerebrovascular changes in CAA-related ICH. Between 2011 and 2015, biopsy-confirmed cases of CAA were retrieved and clinical, radiological and pathological features were reviewed. The spectrum of vascular alterations was evaluated and amyloid deposition was graded in accordance with the Greenberg and Vonsattel scale. Seven cases of sporadic CAA [5 males and 2 females] were diagnosed, none of whom were suspected to have CAA pre-operatively. Six presented with large intracerebral haematoma (ICH) requiring neurosurgical intervention (age range: 56-70 years) and one had episodic headache and multiple microhaemorrhages requiring a diagnostic brain biopsy (45 years). In the presence of large ICH, vascular amyloid deposits were of moderate to severe grade (grade 4 in 4, grades 2 and 3 in 1 case each) with predominant involvement of medium (200-500 μm) to large (> 500 μm) leptomeningeal vessels. Fibrinoid necrosis was noted in four. Two were hypertensive and on antiplatelet agents. β-Amyloid plaques were detected in two, one of whom had symptomatic dementia. MRI performed in 3 of 6 cases with ICH did not reveal any microhaemorrhages. Amyloid deposits in small (50-200 μm) to medium (200-500 μm) calibre intracortical vessels produced parenchymal microhemorrhages. Histopathological examination of ICH is essential for diagnosing CAA. The vascular calibre rather than grade of amyloid deposits dictates size of the bleed. Presence of co-morbidities such as antiplatelet agents may predispose to haemorrhage.

Hemorrhagic and non-hemorrhagic causes of signal loss on susceptibility-weighted imaging

Susceptibility-weighted imaging (SWI) plays a key role in an emergency setting. SWI takes the intrinsic properties of materials being scanned and creates a visual representation of their effects on the magnetic field, thereby differentiating a number of pathologies. Magnetic resonance imaging (MRI) is now more often used, especially when computed tomography (CT) is inconclusive or even negative. Often, clinicians prefer to obtain an MRI first. This article will review the various hemorrhagic and non-hemorrhagic causes of low signal on SWI. There will be a focus on the distribution patterns of low signal on SWI in pathologies such as diffuse axonal injury, cerebral amyloid angiopathy, and cerebral fat embolism. It is important to recognize these patterns of susceptibility, as the radiologist may be the first to give an accurate diagnosis and therefore, directly impact clinical management.

Cerebral amyloid angiopathy: Review of clinico-radiological features and mimics

Cerebral amyloid angiopathy (CAA) is an important cause of lobar intracerebral haemorrhage (ICH) in the elderly, but has other clinico-radiological manifestations. In the last two decades, certain magnetic resonance imaging (MRI) sequences, namely gradient-recalled echo imaging and the newer and more sensitive susceptibility-weighted imaging, have been utilised to detect susceptibility-sensitive lesions such as cerebral microbleeds and cortical superficial siderosis. These can be utilised sensitively and specifically by the Modified Boston Criteria to make a diagnosis of CAA without the need for 'gold-standard' histopathology from biopsy. However, recently, other promising MRI biomarkers of CAA have been described which may further increase precision of radiological diagnosis, namely chronic white matter ischaemia, cerebral microinfarcts and lobar lacunes, cortical atrophy, and increased dilated perivascular spaces in the centrum semiovale. However, the radiological manifestations of CAA, as well as their clinical correlates, may have other aetiologies and mimics. It is important for the radiologist to be aware of these clinico-radiological features and mimics to accurately diagnose CAA. This is increasingly important in a patient demographic that has a high prevalence for use of antiplatelet and antithrombotic medications for other comorbidities which inherently carries an increased risk of ICH in patients with CAA.

Subdural Hemorrhage from Cerebral Amyloid Angiopathy-Related Intracerebral Hemorrhage: A Risk Factor for Postoperative Hemorrhage

OBJECTIVE

Surgical treatment for cerebral amyloid angiopathy (CAA)-related intracerebral hemorrhage (ICH) is controversial. A subset of CAA-related ICH with associated subdural hemorrhage (SDH) has been reported. This study aimed to evaluate clinical results and surgical outcomes of this type of ICH with associated SDH.

METHODS

Study participants included 98 patients with CAA-related ICH who met Boston criteria. Patients were divided into an SDH group and a control (no SDH) group. Clinical and neuroimaging features and surgical outcomes of the 2 groups were compared.

RESULTS

Lobular shape of hematoma was found significantly more often in the SDH group (65.7% [23/35]) compared with the control group (25.4% [16/63]; P < 0.001). Subarachnoid hemorrhage was found significantly more often in the SDH group (34.3% [12/35]) compared with the control group (7.9% [5/63]; P = 0.001). The rate of postoperative hemorrhage was significantly higher in the SDH group (61.5% [8/13]) than in the control group (16.2% [6/37]; P = 0.006). The frequency of occurrence of postoperative hemorrhage was significantly higher in the SDH group (13/13) than in the control group (6/37; P = 0.017). A good surgical outcome occurred in none (0/12) of the patients in the SDH group, whereas a good surgical outcome occurred in 51.9% (14/27) of patients in the control group (P = 0.006).

CONCLUSIONS

Patients with CAA-related ICH with associated SDH more frequently have postoperative hemorrhage and have a worse surgical outcome. These findings are useful in choosing therapeutic methods and preoperative planning of surgical strategy.

Multimodality Review of Amyloid-related Diseases of the Central Nervous System

Amyloid-β (Aβ) is ubiquitous in the central nervous system (CNS), but pathologic accumulation of Aβ results in four distinct neurologic disorders that affect middle-aged and elderly adults, with diverse clinical presentations ranging from chronic debilitating dementia to acute life-threatening intracranial hemorrhage. The characteristic imaging patterns of Aβ-related CNS diseases reflect the pathophysiology of Aβ deposition in the CNS. Aβ is recognized as a key component in the neuronal damage that characterizes the pathophysiology of Alzheimer disease, the most common form of dementia. Targeted molecular imaging shows pathologic accumulation of Aβ and tau protein, and fluorine 18 fluorodeoxyglucose positron emission tomography and anatomic imaging allow differentiation of typical patterns of neuronal dysfunction and loss in patients with Alzheimer disease from those seen in patients with other types of dementia. Cerebral amyloid angiopathy (CAA) is an important cause of cognitive impairment and spontaneous intracerebral hemorrhage in the elderly. Hemorrhage and white matter injury seen at imaging reflect vascular damage caused by the accumulation of Aβ in vessel walls. The rare forms of inflammatory angiopathy attributed to Aβ, Aβ-related angiitis and CAA-related inflammation, cause debilitating neurologic symptoms that improve with corticosteroid therapy. Imaging shows marked subcortical and cortical inflammation due to perivascular inflammation, which is incited by vascular Aβ accumulation. In the rarest of the four disorders, cerebral amyloidoma, the macroscopic accumulation of Aβ mimics the imaging appearance of tumors. Knowledge of the imaging patterns and pathophysiology is essential for accurate diagnosis of Aβ-related diseases of the CNS. (©)RSNA, 2016.

Lobar intracerebral haematomas: Neuropathological and 7.0-tesla magnetic resonance imaging evaluation

BACKGROUND AND PURPOSE

The Boston criteria for cerebral amyloid angiopathy (CAA) need validation by neuropathological examination in patients with lobar cerebral haematomas (LCHs). In "vivo" 1.5-tesla magnetic resonance imaging (MRI) is unreliable to detect the age-related signal changes in LCHs. This post-mortem study investigates the validity of the Boston criteria in brains with LCHs and the signal changes during their time course with 7.0-tesla MRI.

MATERIALS AND METHODS

Seventeen CAA brains including 26 LCHs were compared to 13 non-CAA brains with 14 LCHs. The evolution of the signal changes with time was examined in 25 LCHs with T2 and T2* 7.0-tesla MRI.

RESULTS

In the CAA group LCHs were predominantly located in the parieto-occipital lobes. Also white matter changes were more severe with more cortical microinfarcts and cortical microbleeds. On MRI there was a progressive shift of the intensity of the hyposignal from the haematoma core in the acute stage to the boundaries later on. During the residual stage the hyposignal mildly decreased in the boundaries with an increase of the superficial siderosis and haematoma core collapse.

CONCLUSIONS

Our post-mortem study of LCHs confirms the validity of the Boston criteria for CAA. Also 7.0-tesla MRI allows staging the age of the LCHs.

Development of Cerebral Microbleeds in the APP23-Transgenic Mouse Model of Cerebral Amyloid Angiopathy-A 9.4 Tesla MRI Study

Background: Cerebral amyloid angiopathy (CAA) is characterized by extracellular deposition of amyloid β (Aβ) around cerebral arteries and capillaries and leads to an increased risk for vascular dementia, spontaneous lobar hemorrhage, convexal subarachnoid hemorrhage, and transient focal neurological episodes, which might be an indicator of imminent spontaneous intracerebral hemorrhage. In CAA cerebral microbleeds (cMBs) with a cortical/juxtacortical distribution are frequently observed in standard magnetic resonance imaging (MRI). In vivo MRI of transgenic mouse models of CAA may serve as a useful tool to investigate translational aspects of the disease.

Materials and Methods: APP23-transgenic mice demonstrate cerebrovascular Aβ deposition with subsequent neuropathological changes characteristic for CAA. We performed a 9.4 Tesla high field MRI study using T2, T2* and time of flight-magnetic resonance angiograpy (TOF-MRA) sequences in APP23-transgenic mice and wildtype (wt) littermates at the age of 8, 12, 16, 20 and 24 months, respectively. Numbers, size, and location of cMBs are reported.

Results: T2* imaging demonstrated cMBs (diameter 50–300 μm) located in the neocortex and, to a lesser degree, in the thalamus. cMBs were detected at the earliest at 16 months of age. Numbers increased exponentially with age, with 2.5 ± 2 (median ± interquartilrange) at 16 months, 15 ± 6 at 20 months, and 31.5 ± 17 at 24 months of age, respectively.

Conclusion: We report the temporal and spatial development of cMBs in the aging APP23-transgenic mouse model which develops characteristic pathological patterns known from human CAA. We expect this mouse model to serve as a useful tool to non-invasively monitor mid- and longterm translational aspects of CAA and to investigate experimental therapeutic strategies in longitudinal studies.

Imaging Findings of Cerebral Amyloid Angiopathy, Aβ-Related Angiitis (ABRA), and Cerebral Amyloid Angiopathy-Related Inflammation: A Single-Institution 25-Year Experience

Vascular inflammation is present in a subset of patients with cerebral amyloid angiopathy (CAA) and has a major influence in determining the disease manifestations. Radiological characterization of this subset is particularly important to achieve early recognition and treatment. We conducted this study to investigate the role of imaging in differentiating CAA with and without inflammation. We reviewed neuroimaging findings for 54 patients seen at Mayo Clinic over 25 years with pathological evidence of CAA and with available neuroimaging at the time of diagnosis. Clinical data were also recorded. Patients were grouped into CAA alone (no vascular inflammation), Aβ-related angiitis or ABRA (angiodestructive inflammation), and CAA-related inflammation or CAA-RI (perivascular inflammation). Imaging findings at presentation were compared among patient subgroups. Radiological features supporting a diagnosis of ABRA or CAA-RI were identified. Radiologic findings at diagnosis were available in 27 patients with CAA without inflammation, 22 with ABRA, and 5 with CAA-RI. On MRI, leptomeningeal disease alone or with infiltrative white matter was significantly more frequent at presentation in patients with ABRA or CAA-RI compared with those with CAA (29.6% vs. 3.7%, P = 0.02; and 40.7% vs. 3.7%, P = 0.002, respectively), whereas lobar hemorrhage was more frequent in patients with CAA (62.3% vs. 7.4%, P = 0.0001). Overall, leptomeningeal involvement at presentation was present in 70.4% of patients with ABRA or CAA-RI and in only 7.4% of patients with CAA (P = 0.0001). The sensitivity and specificity of leptomeningeal enhancement to identify patients with ABRA or CAA-RI were 70.4% and 92.6%, respectively, whereas the positive likelihood ratio (LR) was 9.5. The sensitivity and specificity of intracerebral hemorrhage to identify patients with CAA were 62.9% and 92.6%, respectively, whereas the positive LR was 8.5. Microbleeds were found in 70.4% of patients with inflammatory CAA at presentation. In conclusion, leptomeningeal enhancement and lobar hemorrhage at presentation may enable differentiation between CAA with and without inflammation. The identification at initial MRI of diffuse cortical-subcortical microbleeds in elderly patients presenting with infiltrative white matter process or prominent leptomeningeal enhancement is highly suggestive of vascular inflammatory CAA.

Cerebral Amyloid Angiopathy Presenting with Synchronous Bilateral Intracerebral Macrohemorrhages

Cerebral amyloid angiopathy (CAA) is the deposition of amyloid proteins in the cerebrovasculature, which can lead to intracerebral hemorrhage. Intracerebral hemorrhage in CAA often presents with microhemorrhages and, less frequently, with more devastating macrohemorrhages. We present a case of CAA-related synchronous bilateral intracerebral macrohemorrhage which, to our knowledge, has yet to be reported in the literature, and postulate its relationship to antiplatelet therapy and transient elevations in blood pressure.

Hemorrhagic cerebrovascular disease

Primary or nontraumatic spontaneous intracerebral hemorrhage (ICH) accounts for 10-15% of all strokes, and has a poor prognosis. ICH has a mortality rate of almost 50% when associated with intraventricular hemorrhage within the first month, and 80% rate of dependency at 6 months from onset. Neuroimaging is critical in identifying the underlying etiology and thus assisting in the important therapeutic decisions. There are several imaging modalities available in the workup of patients who present with ICH, including computed tomography (CT), magnetic resonance imaging (MRI), and digital subtraction angiography (DSA). A review of the current imaging approach, as well as a differential diagnosis of etiologies and imaging manifestations of primary versus secondary intraparenchymal hemorrhage, is presented. Active bleeding occurs in the first hours after symptom onset, with early neurologic deterioration. Identifying those patients who are more likely to have hematoma expansion is an active area of research, and there are many ongoing therapeutic trials targeting this specific patient population at risk.

[A subacute dementia: Inflammatory cerebral amyloid angiopathy]

We report a case of inflammatory cerebral amyloid angiopathy (CAA) that led to rapid cognitive decline, seizures, visual hallucinations, hyperproteinorrachia and right hemispheric leukopathy. Brain biopsy gave the diagnosis of CAA. Although no inflammatory infiltrate was found in the biopsy sample, corticosteroids led to a regression of the radiological lesions without significant clinical improvement. CAA is a rare disease, defined by lesions of classical cerebral amyloid angiopathy and perivascular infiltrates in contact with the affected vessels. In cases of rapidly progressive dementia associated with leukopathy, inflammatory amyloid angiopathy should be considered as cognitive disorders may improve after immunosuppressive therapy.

Genetic determinants of white matter hyperintensities and amyloid angiopathy in familial Alzheimer's disease

Familial Alzheimer's disease (FAD) treatment trials raise interest in the variable occurrence of cerebral amyloid angiopathy (CAA); an emerging important factor in amyloid-modifying therapy. Previous pathological studies reported particularly severe CAA with postcodon 200 PSEN1 mutations and amyloid beta coding domain APP mutations. As CAA may manifest as white matter hyperintensities (WMH) on magnetic resonance imaging, particularly posteriorly, we investigated WMH in 52 symptomatic FAD patients for associations with mutation position. WMH were visually rated in 39 PSEN1 (18 precodon 200); 13 APP mutation carriers and 25 healthy controls. Ten PSEN1 mutation carriers (5 precodon 200) had postmortem examination. Increased WMH were observed in the PSEN1 postcodon 200 group and in the single APP patient with an amyloid beta coding domain (p.Ala692Gly, Flemish) mutation. WMH burden on MRI correlated with severity of CAA and cotton wool plaques in several areas. The precodon 200 group had younger ages at onset, decreased axonal density and/or integrity, and a greater T-lymphocytic response in occipital deep white matter. Mutation site contributes to the phenotypic and pathological heterogeneity witnessed in FAD.

Clinical Neuropathological Analysis of 10 Cases of Cerebral Amyloid Angiopathy-Related Cerebral Lobar Hemorrhage

Objective

The clinical and pathological characteristics of 10 cases of cerebral amyloid angiopathy (CAA)-related cerebral lobar hemorrhage (CLH) that was diagnosed at autopsy were investigated to facilitate the diagnosis of this condition.

Methods

The clinical characteristics of 10 cases of CAA-related CLH were retrospectively reviewed, and a neuropathological examination was performed on autopsy samples.

Results

The 10 cases included two with a single lobar hemorrhage and eight with multifocal lobar hemorrhages. In all of the cases, the hemorrhage bled into the subarachnoid space. Pathological examinations of the 10 cases revealed microaneurysms in two, double barrel-like changes in four, multifocal arteriolar clusters in five, obliterative onion skin-like intimal changes in four, fibrinoid necrosis of the vessels in seven, neurofibrillary tangles in eight, and senile plaques in five cases.

Conclusion

CAA-related CLHs were located primarily in the parietal, temporal, and occipital lobes. These hemorrhages normally consisted of multiple repeated CLHs that frequently bled into the subarachnoid space. CAA-associated microvascular lesions may be the pathological factor underlying CLH.

Subtle neuropsychiatric and neurocognitive changes in hereditary gelsolin amyloidosis (AGel amyloidosis)

Hereditary gelsolin amyloidosis (AGel amyloidosis) is an autosomal dominant form of systemic amyloidosis caused by a c.640G>A or c.640G>T mutation in the gene coding for gelsolin. Principal clinical manifestations include corneal lattice dystrophy, cranial neuropathy and cutis laxa with vascular fragility. Signs of minor CNS involvement have also been observed, possibly related to cerebral amyloid angiopathy (CAA). To investigate further if AGel amyloidosis carries a risk for a specific neuropsychological or psychiatric symptomatology we studied 35 AGel patients and 29 control subjects. Neuropsychological tests showed abnormalities in visuocontructional and -spatial performance in AGel patients, also some indication of problems in processing efficacy was found. At psychiatric evaluation the patient group showed more psychiatric symptomatology, mainly depression. In brain MRI, available in 16 patients and 14 controls, we found microhemorrhages or microcalcifications only in the patient group, although the number of findings was small. Our study shows that AGel amyloidosis can be associated with visuoconstructional problems and depression, but severe neuropsychiatric involvement is not characteristic. The gelsolin mutation may even induce cerebrovascular fragility, but further epidemiological and histopathological as well as longitudinal follow-up studies are needed to clarify gelsolin-related vascular pathology and its clinical consequences.

Systemic lupus erythematosus: prediction by MRI of the subsequent development of brain lesions

RATIONALE AND OBJECTIVES

Many patients with systemic lupus erythematosus (SLE) manifest the recurrence of new brain lesions on follow-up magnetic resonance imaging (MRI) scans. We assessed whether the initial MRI findings help to predict the subsequent development of brain lesions in patients with SLE.

MATERIALS AND METHODS

We enrolled 64 patients with SLE who had undergone initial and follow-up MRI studies. Two radiologists reviewed and categorized the initial MRI findings and divided the patients into those with no lesions on the initial and follow-up MRI scans (group A, n = 18), those with lesions on the initial scans only (group B, n = 32), and those with lesions on the first and new lesions on the follow-up MRI scans (group C, n = 14). We then looked for independent predictors of the subsequent development of brain lesions, such as antiphospholipid syndrome (APS) and findings on the initial MRI studies.

RESULTS

The incidence of lacunar and localized cortical infarcts was significantly greater in group C than group B (50% vs. 0%, P < .001 and 50% vs. 9%, P < .05, respectively). Multivariate logistic regression analysis indicated that lacunar or localized cortical infarcts on the initial MRI scans were independent predictors of the subsequent development of brain lesions (odds ratio [OR]: 5.412, 95% confidence interval [CI]: 1.18-24.85, P = .03), whereas the presence of APS was not (OR: 0.621, 95% CI: 0.18-2.19).

CONCLUSIONS

The presence of lacunar and/or localized cortical infarcts on initial MRI scans may predict the development of new brain lesions in patients with SLE.

Imaging spectrum of sporadic cerebral amyloid angiopathy: multifaceted features of a single pathological condition

OBJECTIVES

Sporadic cerebral amyloid angiopathy (CAA) is common cause of cerebrovascular disorders that predominantly affect elderly patients. When symptomatic, cortical-subcortical intracerebral haemorrhage (ICH) in the elderly is the most well-known manifestation of CAA. Furthermore, the clinical presentation varies from a sudden neurological deficit to seizures, transient symptoms and acute progressive cognitive decline. Despite its clinical importance, this multifaceted nature poses a diagnostic challenge for radiologists. The aims of this study were to expound the characteristics of neuroimaging modalities, which cover a wide spectrum of CAA-related imaging findings, and to review the various abnormal findings for which CAA could be responsible.

CONCLUSIONS

Radiologically, in addition to typical ICH, CAA leads to various types of abnormal findings, including microbleed, subarachnoid haemorrhage, superficial siderosis, microinfarction, reversible oedema, and irreversible leukoaraiosis. Taking into consideration the clinical importance of CAA-related disorders such as haemorrhagic risks and treatable oedema, it is necessary for radiologists to understand the wide spectrum of CAA-related imaging findings.

TEACHING POINTS

• To describe the characteristics of imaging modalities and findings of CAA-related disorders. • MRI, especially gradient echo sequences, provides the useful information of CAA-related haemosiderin depositions. • To understand the wide spectrum of CAA-related neuroimaging and clinical features is important.

A unique case report of cerebral amyloid angiopathy with literature review

Cerebral amyloid angiopathy (CAA) is a cerebrovascular disease in which β-amyloid peptides are deposited in leptomeningeal, cortical, and subcortical arteries, arterioles, and capillaries. Most individuals with CAA are asymptomatic. However, patients with CAA can present with cognitive impairment and other neurologic deficits caused by vascular wall amyloid deposition leading to hemorrhage. We present a unique case of CAA in a middle-aged woman with a history of cerebral cortex microhemorrhages and cortical edema. Imaging and pathology findings suggested CAA as the main etiology of this presentation. This is a very rare case of CAA coexisting with aneurysmal subarachnoid hemorrhage. Finally, we present a full discussion on the pathogenesis, clinical features, diagnosis, and treatment of CAA.

Brain MR findings in patients with systemic lupus erythematosus with and without antiphospholipid antibody syndrome

BACKGROUND AND PURPOSE

Antiphospholipid syndrome may affect the incidence and pathogenesis of cerebrovascular diseases in patients with systemic lupus erythematosus. We compared the spectrum of MR findings in patients with systemic lupus erythematosus with and without antiphospholipid syndrome.

MATERIALS AND METHODS

We identified 256 patients with systemic lupus erythematosus (45 with, 211 without antiphospholipid syndrome) who underwent MR studies; in 145 (57%), we detected abnormalities. These were categorized as large territorial, lacunar, localized cortical, and borderzone infarctions and as microembolisms, basal ganglia lesions, callosal lesions, hemorrhages, and white matter hyperintensity on T2-weighted and/or FLAIR images, and as stenotic arterial lesions on MR angiograms. Logistic regression analysis was performed to compare the MR findings in patients with systemic lupus erythematosus with and without antiphospholipid syndrome, with patient age and antiphospholipid syndrome as the covariates.

RESULTS

Abnormal MR findings were more common in patients with systemic lupus erythematosus with antiphospholipid syndrome (73% versus 53%). Large territorial (P = .01), lacunar (P = .01), localized cortical (P < .01), borderzone infarcts (P < .01), basal ganglia lesions (P = .03), stenotic arterial lesions (P = .04), and the rate of positive findings on MR imaging (P = .01) were significantly associated with antiphospholipid syndrome. Irrespective of age, significantly more patients with antiphospholipid syndrome manifested lacunar infarcts in the deep white matter (P < .01), localized cortical infarcts in the territory of the MCA (P < .01), bilateral borderzone infarcts (P < .01), and anterior basal ganglia lesions (P = .01).

CONCLUSIONS

Abnormal MR findings were more common in patients with systemic lupus erythematosus with than in those without antiphospholipid syndrome. Large territorial infarctions, lacunar infarctions in the deep white matter, localized cortical infarctions in the MCA territory, bilateral borderzone infarctions, anterior basal ganglia lesions, and stenotic arterial lesions are common MR findings in patients with systemic lupus erythematosus with antiphospholipid syndrome.

Recurrent craniospinal subarachnoid hemorrhage in cerebral amyloid angiopathy

Cerebral amyloid angiopathy (CAA) usually manifests as cerebral hemorrhage, especially as nontraumatic hemorrhages in normotensive elderly patients. Other manifestations are subarachnoid (SAH), subdural, intraventricular hemorrhage (IVH) and superficial hemosiderosis. A 52-year-old hypertensive woman presented with recurrent neurological deficits over a period of 2 years. Her serial brain magnetic resonance imaging and computed tomography scans showed recurrent SAH hemorrhage, and also intracerebral, IVH and spinal hemorrhage, with superficial siderosis. Cerebral angiograms were normal. Right frontal lobe biopsy showed features of CAA. CAA can present with unexplained recurrent SAH hemorrhage, and may be the initial and prominent finding in the course of disease in addition to superficial cortical siderosis and intracerebal and spinal hemorrhages.